Thoracic Ultrasonography and Bronchoalveolar Lavage Fluid Analysis in Holstein Calves with Subclinical Lung Lesions

Development of a classification system for lung ultrasonographic findings in calves based on the association with cure and production outcomes

The primary objective of this study was to determine associations between ultrasound-based classification systems (using maximum consolidations depth, number of quadrants with consolidation, and consolidation location), clinical indicators, and performance outcomes (ultrasonographic cure, ADG, and cold carcass weight [CCW]) in veal calves following oral metaphylaxis. A retrospective cohort study was conducted on 1,090 white veal calves originating from 3 Belgian veal herds. Clinical scoring and quick thoracic ultrasound (qTUS) follow-up were done by 4 experienced operators at arrival (wk 0), at the start of the first metaphylactic treatment with doxycycline (treatment initiation, wk 1), at the end of this metaphylactic treatment (short-term evaluation, wk 3) and on a long-term evaluation point (wk 10-12). Cure was defined as complete reaeration of previously consolidated lung tissue. Pathogens were identified using culture and nanopore sequencing. One week after arrival, healthy lungs (no consolidation), mild pneumonia (consolidation <1 cm), moderate pneumonia (consolidation 1-2.5 cm), and severe pneumonia (consolidation ≥3 cm) were identified in 46.9%, 12.4%, 21.4%, and 19.4% of calves, respectively. Short-term cure was 59.3% for calves with mild pneumonia, 50.2% for calves with moderate pneumonia, and 32.7% for calves with severe pneumonia, resulting in a total short-term cure of 45.9%. Coronavirus, respiratory syncytial virus, influenza D virus, and Mycoplasmopsis bovis were circulating during treatment. At the long-term evaluation point (wk 10-12), final cure was 59.3%, 55.8%, and 40.3% for calves with mild, moderate, and severe pneumonia at treatment initiation, respectively. Multivariable regression models indicated that different interactions between qTUS categories and number of affected quadrants were associated with short- and long-term odds of cure. Generated models resulted in 3 classification methods, either based on maximum consolidation depth, number of affected quadrants, or an integrated system of both. Calves with clinical pneumonia (Wisconsin score ≥5 and lung consolidation ≥1 cm) had decreased short-term odds to be cured after metaphylaxis compared with calves with subclinical pneumonia (Wisconsin score <5 and lung consolidation ≥1 cm; odds ratio = 0.43; 95% CI: 0.27-0.67). For calves with severe pneumonia in wk 10-12, when compared with calves in a lower qTUS category, ADG and CCW were reduced by 104 g/day (SD = 13; 95% CI: 78-130) and 7.1kg (SD = 1.9; 95% CI: 3.4-10.9), respectively. Categorization based on maximum consolidation depth, the number of affected quadrants, or an integrated system of both has the potential to be included in an ultrasound scoring system. However, based on the practicality for recording, reporting, and follow-up, the authors recommend categorizing calves into mild, moderate, and severe pneumonia based on maximum consolidation depth measurement, referred to as qTUS score, as a practical classification system for ultrasonographic lung assessment in calves.

Association of Lung Consolidation Depth With Pathogens Isolated From Bronchoalveolar Lavage Fluid in Calves With Clinical Signs of Respiratory Disease

BACKGROUND

The depth of lung consolidation (≥ 1 and ≥ 3 cm) on thoracic ultrasonography (TUS) is increasingly used as a criterion for antimicrobial treatment. However, its association with bacterial infections remains unclear.

OBJECTIVES

To investigate the associations of clinical and ultrasonographic findings, particularly consolidation depth, with opportunistic bacterial infections (OBI), viral infections, or Mycoplasma bovis (also known as Mycoplasmopsis bovis) infections. Different definitions of OBI were explored, based on various combinations of bacterial species, with or without a neutrophilic profile on cytology.

ANIMALS

Eighty-six group-housed calves with at least one clinical sign of respiratory disease from 19 herds experiencing a respiratory epidemic.

METHODS

Cross-sectional study. A physical examination, TUS, and non-bronchoscopic bronchoalveolar lavage were performed. The definitions of OBI were based on semi-quantitative culture results and cytology.

RESULTS

Calves with consolidations of ≥ 0.5 cm had higher odds of having an OBI considering most definitions, on M. bovis isolation (odds ratio [OR] = 57.3; 95% confidence interval [CI] = 1.5-2300; p = 0.03) and isolation of a bacterial agent in general (OR = 15.5; 95% CI = 2.3-100; p = 0.01). Animals with consolidation ≥ 1 cm had higher odds of OBI considering all definitions, virus isolation (OR = 15.6; 95% CI = 1.0-240; p = 0.05) and isolation of a bacterial agent in general (OR = 6.9; 95% CI = 1.7-28; p = 0.01). Consolidation ≥ 3 cm, cough, and the California score were not significantly associated with OBI, M. bovis, or both.

CONCLUSION

In herds experiencing a respiratory epidemic, consolidation depths ≥ 0.5 and ≥ 1 cm might indicate respiratory disease with a bacterial component.

Comparison of Diagnostic Methods for Respiratory Disease in Calves Used on Farms With Thoracic Radiography

The most commonly used techniques in the field are the pulmonary auscultation, Wisconsin score (WI), California score (CA), and pulmonary ultrasonography. However, with the exception of the latter, no studies have compared thoracic radiography with other possible techniques in calves. Therefore, the objective of the study was to compare and verify the agreement between clinical score techniques, pulmonary auscultation, and ultrasonographic and radiographic evaluations, considering the latter as reference test. Thirty-three calves were evaluated from 17 to 60 days of age using pulmonary auscultation, Wisconsin score (WI), California score (CA), thoracic radiography, and pulmonary ultrasonography at five preestablished moments and at any time when presenting clinical respiratory disease. Of the 160 evaluations, 21% were positive for thoracic radiography, 21% for ultrasonography, 10% for pulmonary auscultation, 16% for CA score, and 14% for WI score. In the concordance analysis, there was a moderate correlation between thoracic radiography and ultrasonography (k = 0.6035) and between pulmonary auscultation and WI score (k = 0.5833) and CA score (k = 0.5277), and substantial between the WI and CA score methods (k = 0.7258). All techniques used in the study were useful for the diagnosis of pneumonia; however, due to high accuracy and practicality, ultrasonography proved to be an interesting method to be implemented on farms.

An on-farm observational study on the prevalence and associated factors of bacteremia in preweaned dairy calves diagnosed with bronchopneumonia by thoracic ultrasonography

BACKGROUND

Bacteremia is a potential systemic complication of bronchopneumonia (BP) in dairy calves, which increases the risk of sepsis and mortality. However, data on bacteremia in farm conditions is still limited. This study investigates the prevalence of bacteremia in calves with BP on farms, examining isolated pathogens and the associations between thoracic ultrasonography (TUS) and non-endoscopic bronchoalveolar lavage (nBAL) findings.

RESULTS

The study enclosed 13 dairy farms and included 211 eligible preweaned dairy calves, of which 88 were diagnosed with BP based on a highly sensitive threshold of ≥ 1 cm for lung consolidation detected by TUS. The affected calves underwent non-endoscopic bronchoalveolar lavage (nBAL) and blood culture procedures. Blood culture results showed a positivity rate of 6.8%, identifying Salmonella Dublin in five cases and Campylobacter fetus in one case. Twenty-four (27.2%) blood samples grew presumed bacterial contaminants, while 58 (65.9%) samples had no growth. In contrast, nBAL samples revealed a 75% positivity rate, with Pasteurella multocida and Mycoplasma bovis being the most frequently identified pathogens. No associations were observed between TUS-detected lung lesions and bacteremia. Notably, BP pathogens were not identified in blood cultures, except for one instance where Salmonella Dublin was detected in the nBAL and blood culture.

CONCLUSIONS

The study indicates a low prevalence of bacteremia in dairy calves with BP diagnosed through TUS, suggesting that recommending treatment or revisions in disease management related to potential bacteremia in these patients may not be warranted. The findings imply that lung lesions detected via TUS may occur independently of bacteremia, highlighting the value of TUS for early diagnosing and monitoring BP in field conditions.

Evaluating case definitions of respiratory disease in dairy calves: A scoping review

Bovine respiratory disease (BRD) is one of the most common diseases observed in dairy calves in both the pre- and postweaning periods. Despite its common occurrence, no formal synthesis (e.g., scoping review) of the scientific literature has been conducted surrounding diagnosing BRD in dairy calves. As such, the objective of this scoping review was to describe what case definitions for diagnosing BRD in dairy calves have been used in research. An initial search of peer-reviewed journals and the gray literature yielded 12,001 unique articles, of which 307 records containing 358 case definitions were included. Seven categories of diagnostic methods were used to categorize case definitions: clinical scoring systems alone were the most used diagnostic method (n = 148, 41%); followed by physical exam parameters alone (i.e., the study did not provide a detailed description of how the calf was assessed for each component of the physical exam [i.e., no description or scoring options reported]), n = 91, 25%); physical exam parameters in combination with other diagnostic methods (n = 40, 11%); thoracic ultrasound alone (n = 31, 9%); clinical scoring system in combination with other diagnostic methods (n = 23, 7%); clinical scoring system in combination with thoracic ultrasound (n = 10, 3%); and other diagnostic methods (n = 15, 4%). Only two-thirds of publications provided a citation for their case definition (n = 230, 64%), of which the Wisconsin clinical scoring system was most referenced (n = 100, 43%), followed by the California clinical scoring system (n = 19, 8%). An attempt was made to compare entire case definitions within each diagnostic method; however, they displayed substantial diversity, which limited the ability to compare them at this level. Instead, counts of individual factors within each case definition (e.g., individual clinical signs) were reported for each diagnostic method. From all case definitions across the 7 diagnostic method categories (n = 358), common factors assessed included cough (n = 224, 63%), nasal discharge (n = 213, 60%), and body temperature (n = 142, 54%). Across all case definitions, additional parameters such as validity were frequently not reported; only 4 (1.1%) were referred to as validated, 9 (2.5%) were being validated in the study, and 28 (7.8%) modified existing case definitions. Additionally, assessment of severity of disease when present (e.g., mild, moderate or severe) was frequently not reported (n = 336, 93.9%). Further, 106 (29.0%) reported assessments of accuracy, 66 (18.4%) of which were reports of qualitative oversight (e.g., training of assessors), and 40 (11.1%) of which were related to a quantitative assessment of accuracy (e.g., sensitivity and specificity). Parameters surrounding conducting the assessment were also extracted, for example how often it was conducted (most common: at least daily, n = 120, 33.5%) and who conducted it (most common: information not reported, n = 144, 40.2%). The findings of this scoping review highlighted the need for a validated, standardized set of criteria for BRD diagnosis in dairy calves, achievable through following the methodology of developing a core outcome set.

Genomic analysis of bovine respiratory disease resistance in preweaned dairy calves diagnosed by a combination of clinical signs and thoracic ultrasonography

Bovine respiratory disease (BRD) poses a significant risk of morbidity and mortality in preweaned dairy calves. Research indicates that this multifactorial disorder can be attributed to the involvement of various pathogens. Currently, there is little information from genome-wide association studies (GWAS) for BRD resistance in young calves based on objective measures and classification of the disease. In this study, we moved forward in phenotyping BRD by coupling two diagnostic tests, the thoracic ultrasonography (TUS) and Wisconsin respiratory score (WISC), in order to assess susceptible and resistant animals to BRD. A total of 240 individuals were scored for BRD using TUS and WISC. A GWAS was performed using a selective genotyping approach to identify Quantitative Trait Loci (QTL) for BRD resistance. A total of 47 calves classified as BRD resistant (TUS ≤  1/ WISC ≤  4) and 47 as BRD susceptible (TUS =  5/ any WISC) were genotyped with the NEOGEN's GGP Bovine 100K SNP chip. QTL were then identified comparing the SNPs allelic frequencies between the two groups. A total of 28 QTL regions (QTLRs) were defined according to significative SNPs, 141 genes were annotated in the defined QTLRs. The genes were functionally classified into 4 main categories, i.e., i) regulation of systemic arterial blood pressure, ii) fertility, iii) immune function, and iv) filament cytoskeleton. Furthermore, 61 out of 141 genes identified here can be considered promising candidate genes since they were already associated with BRD resistance in published GWAS studies in dairy cattle. The ASB9, BMX, EPSTI1, and OLFM4 genes were identified in 4 of the 6 considered studies. This study paves the way for further research to mine the genome for resistance to respiratory diseases, utilizing an accurate classification process.

When to pair: Effects of different pairing ages on dairy calf health, behavior, and performance

Pair housing presents an alternative to individual or larger group housing systems, though the effects of different pairing ages on calf welfare are not well understood. In this study, we examined the effect of pairing age on the performance, health, and behavior of dairy calves. A total of 140 Holstein female calves (n = 70 pairs) were used, paired at 3 stages: early (6-7 d; 48 calves), intermediate (29-30 d; 48 calves), and late (49-50 d; 44 calves). Calves were housed individually before pairing and weaned at 78 ± 2 d of age. Weight measurements were recorded at birth, 30, 50, and 60 d, and at weaning. Calves' behavior was assessed 5 times per week through scan sampling after milk feedings from d 6 to 7 until weaning, and a food neophobia test was conducted at 50 to 51 d. Health assessments were performed 3 times per week by a veterinarian using Wisconsin clinical scores to diagnose diarrhea and bovine respiratory disease, with pulmonary ultrasonography at 55 d. The results suggest no association between pairing age and the prevalence of diarrhea or bovine respiratory disease, although the statistical power was limited. The number of calves with lung consolidation scores above 2 was also unaffected by pairing age. Early-paired calves exhibited more exploration and play behaviors and less idleness, stereotypies, and nonnutritive oral behaviors than late-paired calves. No differences were observed in cross-suckling likelihood across pairing ages. Early-paired calves also showed a shorter latency to touch a novel feed in the food neophobia test, higher calf starter intake during the first 15 d, and greater ADG up to 50 d. Although overall ADG did not differ among pairing ages, early-paired calves were more homogeneous in weaning weight than late-paired calves. In conclusion, early pairing supports calves' initial development, promoting early feeding behavior and growth and enhancing behaviors associated with positive affective states without adverse effects on health or undesirable behaviors.

Echocardiographic Changes Related to Pulmonary Hypertension in Preweaned Dairy Calves With Bronchopneumonia: A Case-Control Study in Commercial Dairy Farms

BACKGROUND

Bronchopneumonia (BP) can cause pulmonary hypertension (PH) and secondary cardiovascular changes.

OBJECTIVES

The aim of this study was to describe PH-related transthoracic Doppler echocardiography (TTE) changes in preweaned dairy calves with BP diagnosed by thoracic ultrasonography (TUS).

ANIMALS

One hundred and sixty-four calves were selected from 11 commercial dairy farms.

METHODS

This is a case-control study. The enrolled calves were grouped according to TUS results into either the control group (with normally aerated lungs) or the BP group (calves with lobar BP). Both groups were then subjected to TTE.

RESULTS

Three echocardiographic variables were statistically different between the two groups, which included 104 healthy calves and 60 diagnosed with BP. The internal end-systolic (LVIDs) and end-diastolic diameters of the left ventricle (LVIDd) were significantly (p = 0.033, 0.034, respectively) lower in BP-affected calves (mean ± standard deviation [SD]: LVIDs, 29.65 ± 3.94 mm in healthy calves vs. 28.21 ± 4.44 mm in BP-affected calves; LVIDd, 49.83 ± 4.7 mm in healthy calves vs. 48.11 ± 5.4 in BP-affected calves). The pulmonary artery internal diameter in end-diastole (PAdia) was significantly larger (p = 0.017) in BP-affected calves (16.81 ± 2.68 mm) than in healthy calves (15.75 ± 2.67 mm).

CONCLUSIONS AND CLINICAL IMPORTANCE

The observed differences in the affected calves were within the normal reference ranges and exhibited clinical relevance. The lack of evident cardiac disturbances indicates that the BP diagnosis in our study sample was made without relevant cardiac alterations, highlighting the potential of TUS's early diagnostic capabilities during BP episodes.

Noninferiority trial in veal calves on the efficacy of oxytetracycline and florfenicol treatment for pneumonia guided by quick thoracic ultrasound

Purchase dependent calf rearing systems, such as the white veal industry, systematically rely on antimicrobial mass medication (metaphylaxis) to counter respiratory tract infections. Despite mounting criticism, the industry fears that without metaphylaxis, mortality would drastically increase. This randomized clinical trial aimed to compare the efficacy of a quick thoracic ultrasonography (qTUS) individualized treatment length between oxytetracycline (OTC) and florfenicol (FF). Regression of maximum consolidation depth <1 cm was used as a criterion for cure and to stop antimicrobial treatment. Additionally, the study assessed the associations of consolidation depth at treatment initiation with cure and treatment duration. The trial involved 320 veal calves, randomly assigned into one of 2 groups: one receiving OTC (n = 160) and the other FF (n = 160) on d 1 (2-d metaphylaxis). Clinical scoring and qTUS were done on d 1 and every 48 h for a 10-d period. After d 1, only calves with consolidations ≥1cm were given further treatment. On each time point, maximum consolidation depth was used to categorize calves into 4 qTUS categories: healthy (no consolidation), mild pneumonia (consolidation <1 cm), moderate pneumonia (consolidation 1-3 cm) and severe pneumonia (consolidation ≥3 cm). Cure, treatment duration and the number of antimicrobial dosages (NAD) were compared between treatment groups. In addition, pathogen identification and antimicrobial susceptibility testing was performed on isolates from nonendoscopic broncho-alveolar lavage fluid. On d 1, 30.0% (96/320) of the calves had consolidation ≥1cm, which increased to 50.9% (162/318) by d 9. After single metaphylactic treatment, cure was 20.9% (9/43) and 20.9% (9/43) in the OTC and FF group, respectively. Calves with severe pneumonia had lower odds to be cured after first treatment than calves with moderate pneumonia (odds ratio = 0.17; 95% CI: 0.04-0.63). By d 9, final cure of the initial cases was 27.9% in both the OTC and FF groups. In both groups, cure was similar at all observation points. Overall, final cure of all calves with either moderate or severe pneumonia during the trial was 41.2% (52/102) and 19.0% (12/63), respectively. Median (Med) treatment duration was 4 d (interquartile range [IQR] = 2-6; minimum [Min] = 2; maximum [Max] = 8) and was similar in both treatment groups. Treatment duration for calves with moderate pneumonia (Med = 6; IQR = 4-6; Min = 2; Max = 8) was lower than the median treatment duration of calves with severe pneumonia (Med = 8; IQR = 4-8; Min = 2; Max = 8). When compared with calves with mild pneumonia on d 1, calves with moderate and severe pneumonia had significantly longer treatment durations. In this study, cure was low and not different between both antimicrobials. Categorizing calves based on consolidation depth appears useful as both cure and treatment duration were different for the mild, moderate, and severe groups.

Development and Progression of Bovine Respiratory Disease Measured Using Clinical Respiratory Scoring and Thoracic Ultrasonography in Preweaned Calves on Dairy Farms in the United Kingdom: A Prospective Cohort Study

The respiratory health of preweaned calves is an important determinant of their health, welfare, and future performance. This prospective cohort study measured bovine respiratory disease (BRD) on 16 dairy farms, including 476 calves in South-west England. Wisconsin and California respiratory scoring and thoracic ultrasonography were performed repeatedly at 7 ± 0.89 day intervals (mean ± SD) at 0-56 days of age (n = 3344 examinations). Cases were localized to the upper or lower respiratory tract, or both, and classified as new, repeat, or chronic. Prevalence and incidence were calculated. Multivariate modeling of factors associated with repeated measurements was performed. Increasing age (OR = 1.05, 95% CI 1.04-1.06) and fecal score (Score 2, OR = 1.78, 95% CI 1.14-2.77) were associated with a lower odds of a healthy BRD subtype, whereas increasing serum total protein (OR = 0.97, 95% CI 0.96-0.99) was protective. Older (OR 1.08, 95% CI 1.06-1.09), male (OR 1.69, 95% CI 1.01-2.84) calves with elevated Wisconsin respiratory scores (≥5, OR 5.61, 95% CI 3.38-9.30) were more likely to have elevated thoracic ultrasound scores. BRD remains common in calves born in UK dairy herds, requiring precise identification and management if preweaning health is to be optimized.

Pharmacokinetics of pradofloxacin, florfenicol, and tulathromycin and response to treatment of steers experimentally infected with Mannheimia hemolytica

BACKGROUND

Bovine respiratory disease (BRD) is an economically important disease in the beef industry, and a major driver of therapeutic antibiotic use. Pharmacokinetic data of these drugs is relatively limited in diseased animals.

HYPOTHESIS/OBJECTIVE

To determine the concentrations of pradofloxacin, florfenicol, and tulathromycin in the airways, plasma, and interstitial fluid (ISF) of steers with a clinically relevant model of bacterial respiratory disease.

ANIMALS

Twenty-four Holstein and Holstein/Jersey cross steers ranging in age from 6 to 15 months.

METHODS

A randomized, blinded clinical trial was performed. After transport stress, steers were inoculated with Mannheimia hemolytica to induce BRD. Upon onset of clinical disease, steers were treated with pradofloxacin, florfenicol or tulathromycin. Blood, ISF, and pulmonary epithelial lining fluid (PELF) samples were obtained for drug concentration determination. Clinical exams and thoracic ultrasound examinations were conducted daily. Animals were euthanized at the end of the study period to assess lung lesions.

RESULTS

Pradofloxacin Cmax in PELF was 0.81 μg/mL (CV = 49.02%) and penetration into the PELF was 203.58% (72%). Florfenicol Cmax in PELF was 2.94 μg/mL (42.1%) and penetration was 230.08% (78.82%). Tulathromycin PELF Cmax was 0.9 μg/mL (45.03%) and PELF penetration was 518.97% (56.59%).

CONCLUSIONS AND CLINICAL IMPORTANCE

There are differences in penetration of the drugs into the ISF and PELF compared to one another and previous data from healthy steers demonstrating the effect of disease on the PK of these drugs.

Choosing the optimal combination of lung lobe evaluation during focused pulmonary ultrasonography in calves

Bovine respiratory disease (BRD) poses significant challenges on beef and dairy farms, affecting mortality rates, animal welfare, and production efficiency. Although pulmonary ultrasonography is highly sensitive and specific for monitoring lung lesions and diagnosing BRD, its practical application could be optimized by focusing on the most commonly affected lung lobes. This study first evaluated the efficacy of focused lung ultrasonography for diagnosing BRD in calves, examining individual lung lobes and their associations versus the extensive lung scanning under various disease prevalence scenarios. Then, the relationship between individual and combined clinical respiratory signs versus lung consolidation was analyzed. In a combined analysis, 193 Holstein calves from a longitudinal study and 112 Angus calves from a cross-sectional study underwent a total of 1,265 complete bilateral thoracic ultrasonographic evaluations from 1 to 6 mo of age. Then, the agreement and sensitivity (Se) of specific lung lobe combinations compared with the findings from total lung ultrasonography was assessed. The classification and regression tree (CART) algorithm was used to suggest an optimal examination sequence, and logistic regression was applied to associate specific clinical signs with the presence of lung consolidation, adjusting for breed and calf age. Findings revealed that the most sensitive areas are the cranial (kappa value [κ] = 0.867; Se = 84.7%) and caudal portion of the right cranial lobe (κ = 0.433; Se = 40.3%), the caudal portion (κ = 0.235; Se = 20.6%) of the left cranial lobe, and the middle lobe (κ = 0.25; Se = 22%). The optimal lobe combinations for focused lung ultrasonography were identified as the right cranial lobe paired with either the left cranial lobe or the middle lobe. Focused techniques achieved Se greater than 94% and maintained good agreement. These focused techniques were relatively robust to various true lung consolidation scenarios. The CART analysis recommended initiating examinations with the right cranial lobe, proceeding to the left cranial lobe, and concluding with the middle lobe. Although spontaneous cough was linked to pneumonia presence, reliance on a single clinical sign is not advised due to low Se (26.8%) and high specificity (85.4%); it should merely prompt further ultrasound assessment. In conclusion, focused lung ultrasonography, especially utilizing the right cranial lobe in conjunction with the left cranial lobe or the middle lobe, emerged as an effective strategy for focused pulmonary ultrasonography, preserving the accuracy of the results.

Bovine Respiratory Disease in Veal Calves: Benefits Associated with Its Early Detection by Lung Ultrasonography and Its Prompt Treatment with a Single Dose of a Fixed Combination of Florfenicol and Meloxicam

Lung ultrasonography can facilitate bovine respiratory disease (BRD) detection and can potentially improve treatment outcomes. In this study, ninety-six veal calves were followed weekly with clinical and lung ultrasound examinations during the production cycle. Thirty-six calves had clinical signs and abnormal lung ultrasound scans (TRT, n = 36) and were promptly treated with florfenicol and meloxicam. Healthy veal calves without clinical signs and lung lesions were enrolled in the control group (CTR, n = 48), while 12 calves were excluded by the study. The clinical (Wisconsin and California scores), ultrasound and lung lesion scores, total lung consolidation area, treatment rates (success, relapse, mortality), average daily gain (ADG), carcass quality, and gross lesions of lungs at slaughterhouse were monitored. Results showed 91.7% of treatments were performed 3-28 days after arrival. Lung lesions occurred five days before the peak of clinical scores. Following treatment, lungs healed within 5 days with high treatment success rates (97.1% success rate in 45 days and 94.9% overall success rate without relapse). Finally, TRT had similar gross lung lesion prevalence, ADG, and carcass quality to CTR. These results suggest that early detection of BRD followed by a prompt treatment can lead to several key benefits for the health and the growth performances of veal calves.

Diagnostic utility of ultrasonography for thoracic and abdominal bacterial and parasitic diseases in ruminants: a comprehensive overview

This review article describes the roles of ultrasound in assessing thoracic and abdominal infectious diseases, mainly bacterial and parasitic ones that affect farm animals, including cattle, camels, sheep, and goats. Ultrasonography is a non-invasive imaging technique used to diagnose infectious diseases affecting the cardiovascular, respiratory, digestive, urinary, and hepatobiliary systems. In cases of thoracic and abdominal infections, ultrasound typically reveals abnormalities in echogenicity and echotexture, the presence of unusual artifacts, and mass formation exerting pressure on surrounding structures. Inflammatory and degenerative changes within the viscera can be identified ultrasonographically by comparing the echogenicity of affected areas with that of the surrounding normal parenchyma, such as in fascioliasis. Bacterial and parasitic infections often result in capsular mass lesions with anechoic contents, as observed in hydatid cysts and cysticercosis, or varying echogenic contents, as observed in liver abscesses. Effusions within the pericardium, pleura, and peritoneum are common ultrasonographic findings in infectious thoracic and abdominal diseases. However, these effusions' echogenicity does not always allow for clear differentiation between transudates and exudates. The routine use of ultrasonography in the evaluation of the chest and abdomen in affected or suspected ruminants is highly beneficial for detection, guiding therapeutic decisions, assessing prognosis, and aiding in the eradication of highly contagious diseases that cause significant economic losses.

Associations between Ultrasonographically Diagnosed Lung Lesions, Clinical Parameters and Treatment Frequency in Veal Calves in an Austrian Fattening Farm

This study evaluated the significance and predictive value of ultrasonographic and physical examination on arrival at an Austrian fattening farm. Treatment frequency and average daily weight gain (ADG) were related to physical and ultrasonographic examination results. Additionally, the effect of an intranasal vaccination in half of the examined calves was studied. The clinical and ultrasonographic health status 600 calves was recorded at the beginning and end of fattening. Half of the calves received an intranasal vaccination (Bovalto® Respi Intranasal). Overall, 44.5% showed an abnormal respiratory scoring (RS) and 56.0% showed signs of respiratory diseases in transthoracic ultrasonography (TUS) at arrival on the farm. For both RS and TUS, a categorization between ILL and HEALTHY was conducted. Results showed lower ADG in ILL calves (RS median: 0.93 kg/d; TUS median: 0.96 kg/d) compared to HEALTHY calves (RS median: 1.01 kg/d; TUS median: 1.01 kg/d). The median ADG was lower in not treated and ILL calves (RS median 0.90 kg/d; TUS: 0.93 kg/d) compared to treated and ILL calves (RS median 1.01 kg/d; TUS: 1.02 kg/d). Vaccination did not affect growth performance or occurrence of ILL, though treatment frequency was lower in VAC calves (17.0% in NVAC; 11.3% in VAC). The implementation of examination protocols for respiratory diseases may have a positive impact on production parameters (e.g., treatment frequency and ADG).

Evaluation of bovine colostrum replacer supplementation to improve weaning transition in Holstein dairy calves

The objective of this randomized controlled trial was to evaluate the efficacy of supplementing bovine colostrum replacer during weaning to reduce intestinal permeability and improve gain. For this experiment, 65 calves were enrolled and housed individually until 70 d of age. Calves were fed milk replacer (150 g/L) 3 times daily with 9, 10.5, 11.25, and 12 L/d offered from d 1 to 7, 8 to 14, 15 to 21, 22 to 56, respectively. Calves were weaned over 8 d from d 57 to 64, receiving a total of 7.8 L in 2 meals per day from d 57 to 60 and 3.8 L/d in 1 feeding from d 61 to 64. At d 57, calves were blocked by birth weight and randomly assigned to 1 of 2 treatments, equal in ME, which were fed once daily during weaning from d 57 to 64: control (CON; n = 31 calves): 3.8 L of milk replacer (150 g/L) fed by nipple bottle, or colostrum supplementation (COL; n = 34): a mixture of 1 L of bovine colostrum replacer (125 g/L) and 3 L of milk replacer (150 g/L) with 3.8 L of of the mixture fed by nipple bottle. Serum IgG was measured within 48 h of birth and BW was taken at d 0, 57, 60, 64, 70, 77, and 84. Starter intake and bovine respiratory disease (BRD) score were measured daily from d 50 to 70, and fecal consistency was examined daily from d 56 to 70. Serum BHB and lung consolidation were evaluated at d 57, 64, and 70, and intestinal permeability was assessed by recovery of chromium-EDTA, lactulose, and d-mannitol from plasma after oral administration at d 56 and 65. Body weight had no difference between treatment groups at the start of weaning, but COL were 2.79 kg (95% CI: 0.90-4.68) and 2.76 kg (95% CI: 0.86-4.65) heavier than CON at d 77 and 84, respectively. Additionally, COL tended to gain 100.00 g/d more than CON calves (95% CI: -10.41-207.13) from d 57 to 84. No differences were observed in any of the other variables measured. Supplementation of bovine colostrum replacer during weaning may improve weight gain, but the mechanism of action is not clear.

Association of clinical respiratory disease signs and lower respiratory tract bacterial pathogens with systemic inflammatory response in preweaning dairy calves

This study investigated the potential associations between 3 acute phase proteins (APP)-haptoglobin, serum amyloid A-and fibrinogen, clinical signs of respiratory disease, and the presence of bacterial pathogens in the lower respiratory tract (LRT) of preweaning dairy calves. This cross-sectional study included 150 preweaning calves (2-86 d old) from 15 large dairy herds in Estonia. Tracheobronchial lavage, blood, and fecal samples were collected from 5 calves showing clinical signs indicative of LRT disease, and samples from 5 calves without clinical signs of LRT disease per herd. All samples collected from these calves were analyzed for concentrations of systemic APP, LRT bacteria, and intestinal pathogens. Heifer blood and bulk tank milk samples were collected for the detection of disease-specific antibodies against bovine herpesvirus 1, bovine viral diarrhea virus, bovine respiratory syncytial virus, and Mycoplasma bovis. Mixed-effects linear regression models were used to analyze the associations of clinical respiratory disease signs and LRT bacteria with APP. Increased plasma fibrinogen concentrations in calves were associated with higher rectal temperature (>39.5°C), increased respiratory rate (>50 breaths/min), and coughing. Increased serum amyloid A concentrations were associated with higher rectal temperature (>39.5°C) and respiratory rate between 40 and 50 breaths/min. Calves with the presence of fecal Cryptosporidium spp. and rectal temperature of 39°C and above had increased serum haptoglobin concentrations. Increased fibrinogen concentrations were associated with the presence of Pasteurella multocida in the calf LRT, whereas increased concentrations of fibrinogen and serum amyloid A were associated with the presence of Trueperella pyogenes. In conclusion, APP showed variable associations with clinical signs of respiratory disease and LRT bacteria. Plasma fibrinogen concentration could be used as a complementary calf-side test to assess systemic inflammation caused by LRT bacteria such as Pasteurella multocida and Trueperella pyogenes in preweaning dairy calves.

Clinical findings and outcome predictors for multinodular pulmonary fibrosis in horses: 46 cases (2009-2019)

BACKGROUND

Prognostic indicators for equine multinodular pulmonary fibrosis (EMPF), an interstitial fibrosing lung disease, are poorly described.

HYPOTHESIS/OBJECTIVES

Describe diagnostic findings and outcome predictors for EMPF.

ANIMALS

Forty-six adult horses with EMPF.

METHODS

Retrospective multicenter case series from 2009 to 2019. Radiographic (n = 27) and ultrasonographic studies (n = 19) from EMPF horses and bronchoalveolar lavage fluid (BALF) cytology from 6 EMPF and 13 asthma cases were independently reviewed and blinded to diagnosis and outcome. Associations between predictor variables and survival were assessed by predictor screening followed by Fisher's exact and Wilcoxon rank sum tests.

RESULTS

Primary clinical findings were weight loss (36/46, 78%), increased respiratory effort (33/46, 72%), tachypnea (32/46, 70%), and fever (18/46, 39%). Macrophage atypia was seen in more EMPF than asthmatic horse BALF (67% vs. 8%; P = .02). Equine herpesvirus 5 (EHV-5) was detected in 24 of 30 (80%) and hyperfibrinogenemia in 25 of 28 (89%) cases. Twenty-seven of 46 horses (59%) and 11 of 45 (24%) survived to discharge and to 3 months, respectively. Three-month survival was associated with lower median (range) respiratory rates (30 [24-36] vs. 41 [30-60] breaths per minute; P = .04), and higher BALF lymphocyte:neutrophil ratios (4.7 [1.4-22] vs. 0.47 [0.11-1.9]; P = .01) and blood lymphocyte counts (1.25 [0.93-2.55] vs. 0.90 [0.70-1.24] × 109/L; P = .03). Imaging findings, EHV-5 detection, and corticosteroid treatment were not associated with survival.

CONCLUSIONS AND CLINICAL IMPORTANCE

Fever is not a sensitive clinical sign of EMPF. Diagnostic testing should be pursued for horses with increased respiratory rate and effort and weight loss. The prognosis for EMPF horses is poor. Corticosteroid treatment does not improve 3-month survival.

Blood gases, acid-base, and metabolic alterations in calves with bronchopneumonia diagnosed via clinical signs and thoracic ultrasonography: A cross-sectional study

BACKGROUND

Bronchopneumonia (BP) in calves potentially causes systemic changes.

OBJECTIVES

To describe metabolic, arterial blood gas, and acid-base disorders in calves with BP diagnosed by thoracic ultrasound (TUS), Wisconsin score (WISC), and combinations of WISC and TUS.

ANIMALS

Two hundred thirty-one dairy preweaned dairy calves from 13 dairy farms.

METHODS

Cross-sectional study. Each calf sequentially underwent arterial blood gas evaluation, WISC score, venous sampling, and TUS. Calves were grouped based on a single diagnostic method and combination of WISC and 2 TUS cutoffs (≥1 cm; ≥3 cm) as healthy, upper respiratory tract infection, subclinical BP, and clinical BP.

RESULTS

Oxygenation and acid-base variables were unaffected. Glucose concentration in TUS-affected calves was significantly lower (P < .001) than in healthy calves (median ≥TUS1cm = 5.2 mmol/L 25%-75% interquartile range [IQR] 4.5-6.1,

CONCLUSIONS AND CLINICAL IMPORTANCE

Clinical signs indicate minor systemic disorders compared to TUS. The abnormalities detected by ultrasonographic examination were moderate and did not deviate from normal reference ranges.

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Key Words

• blood gas analysis
• calves
• clinical signs
• respiratory disease
• thoracic ultrasonography

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MESH Headings

• Animals
• Cattle
• Cross-Sectional Studies
• Cattle Diseases/diagnostic imaging
• Cattle Diseases/blood
• Bronchopneumonia/veterinary
• Bronchopneumonia/diagnostic imaging
• Bronchopneumonia/blood
• Blood Gas Analysis/veterinary
• Ultrasonography/veterinary
• Female
• Male
• Blood Glucose/analysis

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Grants

• University of Milan
• University of Milan

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Affiliation(s)

Antonio Boccardo Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS)Università degli Studi di MilanoLodiItaly
Vincenzo Ferrulli Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS)Università degli Studi di MilanoLodiItaly
Giulia Sala Dipartimento di Scienze VeterinarieUniversità degli Studi di PisaSan Piero a GradoItaly
Donatella Scavone Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS)Università degli Studi di MilanoLodiItaly
Saverio Paltrinieri Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS)Università degli Studi di MilanoLodiItaly
Laura Filippone Pavesi Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS)Università degli Studi di MilanoLodiItaly
Davide Pravettoni Dipartimento di Medicina Veterinaria e Scienze Animali (DIVAS)Università degli Studi di MilanoLodiItaly

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Collaborators Collapse

The role of endoscopy in bovine internal medicine - A review of current indication fields

Endoscopy in bovine internal medicine has come a long way from the first profound research papers in the 1980s to its present-day use. This paper reviews the progress in the 2000s and identifies the main application fields for diagnostic and therapeutic use. Inclusion criteria for scientific papers and reports encompassed focus on endoscopic examination techniques in cattle in the field of internal medicine and publication in a peer reviewed journal (case report/review/original research paper/short communication). Only papers written in English or German language were considered. Studies on laparoscopy, theloscopy, and bronchoscopy show that endoscopic approaches often enable more rapid and accurate diagnosis and treatment options for single diseased animals as well as on a herd level. Oesophagoscopy, rumenoscopy, cystoscopy and thoracoscopy have also been increasingly studied and proven to be safe and effective tools with some limitations in diagnosing and/or treating various diseases in cattle. Scientific approaches explored the epidural space in cattle and comparison of different endoscope systems lead to recommendations for sinuscopy. Yet, this narrative literature review clearly shows that unlike in human medicine, where endoscopy as a minimally invasive technique is used for countless routine procedures every day, there is still some catching up to do in bovine medicine even though the potential of endoscopy in this field has been documented.

Strategies for Bovine Respiratory Disease (BRD) Diagnosis and Prognosis: A Comprehensive Overview

Despite significant advances in vaccination strategies and antibiotic therapy, bovine respiratory disease (BRD) continues to be the leading disease affecting the global cattle industry. The etiology of BRD is complex, often involving multiple microbial agents, which lead to intricate interactions between the host immune system and pathogens during various beef production stages. These interactions present environmental, social, and geographical challenges. Accurate diagnosis is essential for effective disease management. Nevertheless, correct identification of BRD cases remains a daunting challenge for animal health technicians in feedlots. In response to current regulations, there is a growing interest in refining clinical diagnoses of BRD to curb the overuse of antimicrobials. This shift marks a pivotal first step toward establishing a structured diagnostic framework for this disease. This review article provides an update on recent developments and future perspectives in clinical diagnostics and prognostic techniques for BRD, assessing their benefits and limitations. The methods discussed include the evaluation of clinical signs and animal behavior, biomarker analysis, molecular diagnostics, ultrasound imaging, and prognostic modeling. While some techniques show promise as standalone diagnostics, it is likely that a multifaceted approach-leveraging a combination of these methods-will yield the most accurate diagnosis of BRD.

Literature Review of the Principal Diagnostic Tests to Detect Bovine Respiratory Disease in Pre-Weaned Dairy and Veal Calves

Bovine respiratory disease (BRD) is an infection of the upper and lower respiratory tract, characterized by an inflammation of the lung. Different diagnostic tests can be used to detect BRD, including clinical respiratory scoring systems, thoracic auscultation, and imaging tests like thoracic ultrasonography and thoracic radiography. Although commonly used, none of these diagnostic tests are perfect for detecting BRD. This article reviews the advantages and drawbacks of these techniques and their performance in detecting BRD in pre-weaned dairy and veal calves.

Effect of on-arrival bovine respiratory disease vaccination on ultrasound-confirmed pneumonia and production parameters in male dairy calves: A randomized clinical trial

The high degree of commingling and accumulation of stressors during and after transport makes prevention of bovine respiratory disease (BRD) extremely challenging in the veal and dairy beef industry. Upon arrival, vaccination for agents involved in BRD is practically most achievable, but its efficacy under such conditions in dairy veal calves is unknown. Given the high prevalence of subclinical pneumonia in these settings, the primary objective of the present study was to determine the effect of 2 vaccination protocols administered upon arrival against bovine respiratory syncytial virus (BRSV), bovine parainfluenza type 3 virus (BPI-3), and Mannheimia haemolytica on clinical BRD and lung ultrasonographic findings in dairy veal calves. In addition, the effects of vaccination on average daily live weight gain and cold carcass weight were determined. In this randomized clinical trial, 443 male dairy calves were assigned to one of 3 groups: a negative, placebo-controlled group (n = 151), a vaccination group with 2 subcutaneous injections 4 wk apart with an inactivated vaccine containing BRSV, BPI-3, and M. haemolytica (parenteral [PE] group; n = 149) and a second vaccination group receiving an intranasal live-attenuated vaccine containing BRSV and BPI-3 and 2 subcutaneous vaccinations with the same inactivated vaccine as the PE vaccination group (intranasal-parenteral [IN-PE] group; n = 143). Clinical scoring and quick thoracic ultrasonography (qTUS) were performed on all calves on arrival (wk 0), at the peak of respiratory disease (outbreak; wk 1), at the end of the first antimicrobial group treatment (wk 3), and at a long-term evaluation point (wk 10). Culture and nanopore sequencing on nonendoscopic bronchoalveolar lavage (nBAL) samples were used to identify pathogens involved in the outbreak. Upon arrival, 15.1% of the calves had lung consolidation ≥1cm and incidence quickly rose to 42.8% during the outbreak. In both the PE and IN-PE group, the odds of pneumonia in wk 10 were reduced by 62% (odds ratio [OR] = 0.38; 95% confidence interval [CI] = 0.23-0.64) and 41% (OR = 0.59; 95% CI = 0.37-0.96), respectively. Short-term cure rate (50.3%), as determined immediately after the first group antimicrobial treatment, was not influenced by vaccination. In contrast, long-term cure rate, determined at wk 10, was affected by vaccination with higher cure in the PE group compared with the control group (69.4% vs. 51.2%; OR = 2.2; 95% CI = 1.1-5.0). Average daily gain in the first 10 wk of production was not affected by vaccination. Vaccination resulted in an increase in cold carcass weight of 3.5 and 4.3 kg in the PE (95% CI = -0.9-7.9) and IN-PE group (95% CI = -0.17-8.7), respectively. In conclusion, under the conditions of the present study, vaccination upon arrival resulted in a reduced prevalence of pneumonia at wk 10 of production, likely caused both by an improved cure rate of secondary infections and a reduced incidence of new cases between outbreak and long-term evaluation. The present protocol, using qTUS for pneumonia detection and nBAL diagnostics for pathogen identification adds a new dimension to randomized clinical trials on respiratory disease in calves.

Diagnostic and Prognostic Value of Clinical Scoring and Lung Ultrasonography to Assess Pulmonary Lesions in Veal Calves

This study on veal calf respiratory disease assessed the association between an on-farm clinical scoring system and lung ultrasonography with the postmortem inspection of the lungs. The comparisons allowed the calculation of predictive values of the diagnostic methods. In total, 600 calves on an Austrian veal calf farm were examined at the beginning and the end of the fattening period. Overall, the area under the curve (AUC) for ultrasonographic scores was 0.90 (rsp = 0.78) with a sensitivity (Se) of 0.86. The specificity (Sp) was 0.78, and the positive predictive value (PPV) was 0.74. The AUC for the physical examination was 0.76 (rsp = 0.55) with a Se of 0.64, an Sp of 0.81, and a PPV of 0.69. For the combination of ultrasonography and physical examination, an AUC curve of 0.85 (rsp = 0.69) was calculated. A Se of 0.65 and a Sp of 0.88 with a PPV of 0.73 was calculated. This study concluded that both physical and ultrasonographic examination scoring are reliable examination methods for the detection of lung diseases in veal calves.

Differentiating airway inflammation in calves based on cluster analysis of bronchoalveolar lavage fluid cytology

BACKGROUND

Nonbronchoscopic bronchoalveolar lavage (nBAL) is routinely performed in calves, and airway cytology has great potential in airway disease diagnostics. A good reference framework for nBAL cytology is lacking.

OBJECTIVES

To distinguish different cytological profiles in nBAL from grouped housed calves using cluster analysis, and characterize these profiles on individual and herd levels.

ANIMALS

Three hundred thirty-eight group-housed calves from 60 herds (mainly dairy and beef ).

METHODS

Cross-sectional study. Differential counts of white blood cells were determined on nBAL fluid, followed by differentiation of cytological profiles by K-means-based cluster analysis. These profiles were characterized by reference values, decision tree analysis, and associations with clinical, ultrasonographic, bacteriological, and cytological features.

RESULTS

A normal (55.9%), a neutrophilic (41.1%), and an eosinophilic profile (3.0%) were identified. The normal profile was characterized by reference values of 2.3% to 47.4% neutrophils, 35.1% to 95.1% macrophages, 0.4 to 22.9% lymphocytes, and 0.0% to 0.9% eosinophils. The neutrophilic profile was characterized by ≥44.5% neutrophils, <1.6% eosinophils, and <11.5% lymphocytes. This profile was associated with the isolation of Pasteurella multocida, the presence of neutrophils with toxic granulation, and the presence of phagocytosed bacteria in neutrophils. The eosinophilic profile was characterized by eosinophils ≥1.6% (neutrophilia present) or ≥2.4% (neutrophilia absent), and associated with the presence of mast cells. On herd level, the neutrophilic and eosinophilic profiles were present in 85.0% and 15.0% of the herds, respectively.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study provides a first step in the development of cytological guidelines, aiding the assessment of airway health and inflammation in calves through nBAL fluid cytology.

Effect of ultrasonographic lung consolidation on health and growth in dairy calves: A longitudinal study

Bovine respiratory disease (BRD) is a common and complex disease process in calves. Subclinical disease exists and early detection can be challenging due to inconsistent or nonexistent clinical signs. Thoracic ultrasonography (TUS) is often used and has the potential to improve the identification of respiratory diseases. Combining systematic TUS with clinical examination allows distinguishing BRD, including upper respiratory tract disease (clinical signs of respiratory disease, but no significant lung consolidation), clinical pneumonia (clinical signs of respiratory disease along with lung consolidations), and subclinical pneumonia (no clinical signs, but lung consolidations). Data on subclinical pneumonia are scarce, particularly outside of the North American or European contexts similar to Iran in west Asia with a dry and semi-arid climate and intensive breeding systems similar to North America which breeding calves begin in individual boxes, then moving to group pens, and finally to free stall or open shed housing systems. The first objective of this longitudinal study was to use weekly ultrasonography to monitor calves from birth until weaning in an Iranian dairy herd. The second objective was to look for any association between individual lung consolidation episode or cumulative consolidation episodes on preweaning growth. Thoracic ultrasonography was performed on calves (n = 221) weekly from birth to weaning (8 wk), and scanning occasions for each calf were equally distributed with 1-wk intervals (using consolidation threshold ≥3 cm as a specific lung consolidation definition, and ≥1 cm as a more sensitive threshold). Calf body weights were recorded using a weight tape. Other information recorded were transfer of passive immunity (TPI) using serum Brix (%) ≥8.4% as adequate TPI within the first week after birth and the treatment history of the calves. The main strategy for modeling was to determine how long-term lung consolidation affects average daily gain (ADG) during the preweaning period. A linear model was used to determine the effect of the number of weeks with consolidation on ADG. Using consolidation threshold of ≥3 cm, the mean (±SD) of total ADG for calves with no consolidation episode, 1 consolidation episode, and 2 or more consolidation episodes were 0.45 (±0.10), 0.39 (±0.10), and 0.38 (±0.11) kg/d, respectively. In the final multivariable regression analysis model and based on consolidation threshold of ≥3 cm, calves with 1 and 2 or more consolidation episodes had significantly lower ADG ± standard error (SE) of 0.04 ± 0.02 kg/d, and 0.06 ± 0.02 kg/d, respectively compared with animals with no consolidation episode. A total of 20% of calves (46/229 calves that entered the study) were treated for respiratory disease based on clinical signs (based on farmer examination). The final model also included specific confounders related to ADG and their interactions with lung consolidation (TPI and BRD treatment). An overall of 86% of adequate TPI was obtained. Bovine respiratory disease treatment based on farmer diagnosis had a larger negative effect on preweaning ADG than ultrasonography-diagnosed consolidation episodes (lower ADG ± SE of 0.10 ± 0.03 kg/d). When using a more sensitive consolidation threshold (≥1 cm as consolidation), the number of weeks with consolidation was also negatively associated with the ADG in the multivariable linear regression model with significant difference of 0.05 ± 0.02 kg/d for nonconsolidated calves versus calves consolidated for 2 or more weeks and insignificant difference of 0.01 ± 0.02 kg/d for nonconsolidated calves versus calves with 1 consolidation episode.

Bayesian evaluation of the accuracy of a thoracic auscultation scoring system in dairy calves with bronchopneumonia using a standard lung sound nomenclature

BACKGROUND

Although thoracic auscultation (AUSC) in calves is quick and easy to perform, the definition of lung sounds is highly variable and leads to poor to moderate accuracy in diagnosing bronchopneumonia (BP).

HYPOTHESIS/OBJECTIVES

Evaluate the diagnostic accuracy of an AUSC scoring system based on a standard lung sound nomenclature at different cut-off values, accounting for the absence of a gold standard test for BP diagnosis.

ANIMALS

Three hundred thirty-one calves.

METHODS

We considered the following pathological lung sounds: increased breath sounds (score 1), wheezes and crackles (score 2), increased bronchial sounds (score 3), and pleural friction rubs (score 4). Thoracic auscultation was categorized as AUSC1 (positive calves for scores ≥1), AUSC2 (positive calves for scores ≥2), and AUSC3 (positive calves for scores ≥3). The accuracy of AUSC categorizations was determined using 3 imperfect diagnostic tests with a Bayesian latent class model and sensitivity analysis (informative vs weakly informative vs noninformative priors and with vs without covariance between ultrasound and clinical scoring).

RESULTS

Based on the priors used, the sensitivity (95% Bayesian confidence interval [BCI]) of AUSC1 ranged from 0.89 (0.80-0.97) to 0.95 (0.86-0.99), with a specificity (95% BCI) of 0.54 (0.45-0.71) to 0.60 (0.47-0.94). Removing increased breath sounds from the categorizations resulted in increased specificity (ranging between 0.97 [0.93-0.99] and 0.98 [0.94-0.99] for AUSC3) at the cost of decreased sensitivity (0.66 [0.54-0.78] to 0.81 [0.65-0.97]).

CONCLUSIONS AND CLINICAL IMPORTANCE

A standardized definition of lung sounds improved AUSC accuracy for BP diagnosis in calves.

Comparison of thoracic ultrasonography and thoracic radiography between healthy adult horses and horses with bacterial pneumonia using a novel, objective ultrasonographic scoring system

Background

Thoracic ultrasonography (TUS) is widely used in equine practice but comparison to radiography is limited in horses.

Objectives

To validate a novel, objective scoring system for TUS in adult horses and to compare ultrasonographic and radiographic findings.

Animals

13 healthy horses and 9 with confirmed bacterial pneumonia

Methods

Prospective study in which TUS and radiography were performed on healthy horses and those with bacterial pneumonia confirmed by clinical signs and results of transtracheal wash analysis. Ultrasonography was scored utilizing a novel scoring system evaluating number of comet tail lesions, the presence or absence of pleural effusion and/or pulmonary consolidation in each intercostal space. Eighteen horses had thoracic radiographs taken that were scored by a board-certified radiologist utilizing a previously described system. Total scores were recorded and compared between control and diseased patients.

Results/Findings

Ultrasonographic scores were significantly higher in the diseased group (median= 126) than in the control group (median = 20, p = 0.01). Receiver operating characteristics (ROC) analysis identified a sensitivity of 66.7% (95% CI 0.417–1) and specificity of 92.3% (95% CI 0.462–1) for the ability of ultrasonography to identify bacterial pneumonia utilizing a TUS score cutoff of 37.

Conclusions and clinical importance

TUS had moderate sensitivity and high specificity for identification of bacterial pneumonia in adult horses. TUS appears to be an acceptable stand-alone imaging modality for diagnosis of bacterial pneumonia in horses when radiography is not practical.

Can Infectious Disease Control Be Achieved without Antibiotics by Exploiting Mechanisms of Disease Tolerance?

Antimicrobial use in animal agriculture may be contributing to the emerging public health crisis of antimicrobial resistance. The sustained prevalence of infectious diseases driving antimicrobial use industry-wide suggests that traditional methods of bolstering disease resistance are, for some diseases, ineffective. A paradigm shift in our approach to infectious disease control is needed to reduce antimicrobial use and sustain animal and human health and the global economy. Targeting the defensive mechanisms that promote the health of an infected host without impacting pathogen fitness, termed “disease tolerance,” is a novel disease control approach ripe for discovery. This article presents examples of disease tolerance dictating clinical outcomes for several infectious diseases in humans, reveals evidence suggesting a similarly critical role of disease tolerance in the progression of infectious diseases plaguing animal agriculture, and thus substantiates the assertion that exploiting disease tolerance mechanisms can positively impact animal and human health.

Ultrasonographic diagnosis of clinical and subclinical bovine respiratory disease in Holstein calves

Background and Aim:

Bovine respiratory disease (BRD) is the main cause of death in calves, and early BRD diagnosis saves lives. This study aimed to diagnose clinical and subclinical BRD in calves by assessing some biochemical alterations and ultrasonography (USG).

Materials and Methods:

Fifty-four Holstein dairy calves in Al-Sharqiyah Province, Egypt, were used in the study. They were divided into three groups. The first control group consisted of 10 clinically healthy calves. The second group consisted of 34 calves suffering from clinical lower respiratory tract disorders. The third group consisted of 10 subclinical BRD-affected calves. Ultrasonographic examinations of chest and thoracic ultrasound scoring were performed once per 2 weeks for each calf. Blood samples were collected for serum separation to measure albumin (ALB), total protein (TP), ALB, globulin, and haptoglobin (HP).

Results:

The USG revealed small consolidation areas within an aerated lung lobe, a hypoechoic parenchyma of the entire distal lung lobe, and a hypoechoic-circumscribed structure surrounded by an echogenic wall appeared within the lung tissue in calves that suffered from lobular pneumonia, lobar pneumonia, and lung abscess, respectively. However, subclinical cases showed a small consolidation area in the cranial aspects of the right cranial lung lobe. The ultrasound lung score (ULS) was greater in clinical than in subclinical cases. The BRD-affected calves recorded significant increases in serum TP, globulin, and HP. Meanwhile, serum ALB decreased significantly.

Conclusion:

Thoracic ultrasound had a reliable tool in the BRD diagnosis, especially in the early prediction of subclinical cases in newborn calves. In addition, the ULS appeared to be a better classifier than the clinical respiratory score (CRS) for BRD diagnosis. On the other side, it was found that regression models were very useful in assessing the prediction of biochemical blood parameters based on the ULS and CRS in diseased cases.

Thoracic Electrical Impedance Tomography-The 2022 Veterinary Consensus Statement

Electrical impedance tomography (EIT) is a non-invasive real-time non-ionising imaging modality that has many applications. Since the first recorded use in 1978, the technology has become more widely used especially in human adult and neonatal critical care monitoring. Recently, there has been an increase in research on thoracic EIT in veterinary medicine. Real-time imaging of the thorax allows evaluation of ventilation distribution in anesthetised and conscious animals. As the technology becomes recognised in the veterinary community there is a need to standardize approaches to data collection, analysis, interpretation and nomenclature, ensuring comparison and repeatability between researchers and studies. A group of nineteen veterinarians and two biomedical engineers experienced in veterinary EIT were consulted and contributed to the preparation of this statement. The aim of this consensus is to provide an introduction to this imaging modality, to highlight clinical relevance and to include recommendations on how to effectively use thoracic EIT in veterinary species. Based on this, the consensus statement aims to address the need for a streamlined approach to veterinary thoracic EIT and includes: an introduction to the use of EIT in veterinary species, the technical background to creation of the functional images, a consensus from all contributing authors on the practical application and use of the technology, descriptions and interpretation of current available variables including appropriate statistical analysis, nomenclature recommended for consistency and future developments in thoracic EIT. The information provided in this consensus statement may benefit researchers and clinicians working within the field of veterinary thoracic EIT. We endeavor to inform future users of the benefits of this imaging modality and provide opportunities to further explore applications of this technology with regards to perfusion imaging and pathology diagnosis.

Using Machine Learning and Behavioral Patterns Observed by Automated Feeders and Accelerometers for the Early Indication of Clinical Bovine Respiratory Disease Status in Preweaned Dairy Calves

The objective of this retrospective cohort study was to evaluate a K-nearest neighbor (KNN) algorithm to classify and indicate bovine respiratory disease (clinical BRD) status using behavioral patterns in preweaned dairy calves. Calves (N=106) were enrolled in this study, which occurred at one facility for the preweaning period. Precision dairy technologies were used to record feeding behavior with an automated feeder and activity behavior with a pedometer (automated features). Daily, calves were manually health-scored for bovine respiratory disease (clinical BRD; Wisconsin scoring system, WI, USA), and weights were taken twice weekly (manual features). All calves were also scored for ultrasonographic lung consolidation twice weekly. A clinical BRD bout (day 0) was defined as 2 scores classified as abnormal on the Wisconsin scoring system and an area of consolidated lung ≥3.0 cm2. There were 54 calves dignosed with a clinical BRD bout. Two scenarios were considered for KNN inference. In the first scenario (diagnosis scenario), the KNN algorithm classified calves as clinical BRD positive or as negative for respiratory infection. For the second scenario (preclinical BRD bout scenario), the 14 days before a clinical BRD bout was evaluated to determine if behavioral changes were indicative of calves destined for disease. Both scenarios investigated the use of automated features or manual features or both. For the diagnosis scenario, manual features had negligible improvements compared to automated features, with an accuracy of 0.95 ± 0.02 and 0.94 ± 0.02, respectively, for classifying calves as negative for respiratory infection. There was an equal accuracy of 0.98 ± 0.01 for classifying calves as sick using automated and manual features. For the preclinical BRD bout scenario, automated features were highly accurate at -6 days prior to diagnosis (0.90 ± 0.02), while manual features had low accuracy at -6 days (0.52 ± 0.03). Automated features were near perfectly accurate at -1 day before clinical BRD diagnosis compared to the high accuracy of manual features (0.86 ± 0.03). This research indicates that machine-learning algorithms accurately predict clinical BRD status at up to -6 days using a myriad of feeding behaviors and activity levels in calves. Precision dairy technologies hold the potential to indicate the BRD status in preweaned calves.

Lung Ultrasonography and Clinical Follow-Up Evaluations in Fattening Bulls Affected by Bovine Respiratory Disease (BRD) during the Restocking Period and after Tulathromycin and Ketoprofen Treatment

Bovine respiratory disease (BRD) is a global infectious disease, causing decreased well-being and economic losses in livestock, frequently during the restocking period. The aim of this study was to evaluate the feasibility of thoracic ultrasonography (TUS) to assess BRD in restocked animals, and the effectiveness of tulathromycin and ketoprofen treatment in sick animals. A total of 60 Limousin fattening bulls were enrolled. On the day of restocking (T0), the animals were divided into two groups based on TUS assessment of six lung areas: group C (ultrasonography score (US score) < 3) and group D (US score ≥ 3). Group D received a single administration of tulathromycin and ketoprofen at T0: this group was revaluated after 1.5, 3, 7, and 14 days. Both groups were revaluated after 21 days. The two groups showed a significant difference both in US score and clinical symptoms (respiratory score, nasal and ocular discharges, and rectal temperature) at T0. In group D, the treatment was effective in improving the clinical symptoms and US score, particularly reducing the severity of lung lesions. TUS represents a non-invasive and cost-effective tool for BRD early diagnosis and for monitoring treatment efficacy in restocked livestock.

The effect of aerosolized bacterial lysate on experimentally induced Mannheimia haemolytica pneumonia in calves

Bovine respiratory disease (BRD) often occurs during specific periods of increased susceptibility when stress, viral infection, or reduced air quality are thought to suppress respiratory defences. The innate immune system is rapidly responsive and broadly protective and could be a target for preventing BRD during these periods of increased susceptibility. This study tested the hypothesis that stimulation of pulmonary innate immune responses by aerosol delivery of a lysate of killed Escherichia coli and Staphylococcus aureus bacteria would protect calves against Mannheimia haemolytica pneumonia. Ten clean-catch colostrum-deprived Holstein calves were randomly assigned to receive either aerosolized bacterial lysate or saline 24 hours before M. haemolytica challenge. Effects of this treatment on clinical, hematologic, microbiologic, and pathologic outcomes were assessed. Compared to controls, lysate-treated calves had lower serum haptoglobin and blood leukocyte and neutrophil concentrations following M. haemolytica challenge. There were no differences in temperature, heart and respiratory rates, clinical scores, ultrasound lesions, or number of M. haemolytica in the nasal cavity or lung. Thus, treatment with bacterial lysate prior to M. haemolytica challenge appeared to ameliorate early measures of inflammation but did not provide sufficient protection to substantially alter the course of disease.

Bovine Respiratory Disease Considerations in Young Dairy Calves

Raising young dairy calves presents many challenges for producers and veterinarians including losses attributable to BRD. This article will discuss several key concepts for practitioners to consider when applying evidence-based medicine for the control and treatment of BRD in young dairy calves. The authors review BRD complex, provide considerations for diagnostic approaches, and discuss research associated with the control and treatment of BRD.

Ultrasonography of the cranial part of the thorax is a quick and sensitive technique to detect lung consolidation in veal calves

BACKGROUND

In the veal calf industry, bovine respiratory disease is the main cause of morbidity and mortality. Lung ultrasonography (LUS) is an accurate technique to diagnose bronchopneumonia in calves. Due to the economic constraints faced by the industry, a screening technique able to rapidly examine large numbers of calves is required.

OBJECTIVE

To determine if lung ultrasonography focusing on the cranial part of the thorax (1st to 2nd intercostal space (ICS) on the right and 2nd to 3rd on the left) and/or on the middle part of the thorax (3rd to 5th ICS on the right and 4th to 5th on the left) (alternative techniques) are rapid screening techniques as sensitive as LUS of the entire lung (reference technique) to identify calves with lung consolidation lesions.

METHODS

Data on 300 veal calves aged 33.1 ± 8.0 days and weighing on average 67.5 ± 4.0 kg at LUS from two farms were analysed. Systematic LUS of the entire lung was performed on all calves and a lung consolidation score was given to different parts of the thorax. Agreements between the alternative and the reference techniques were measured by Cohen's κ, McNemar's test and weighted κ.

RESULTS

Agreement between LUS focusing on the cranial + middle part or on the cranial part only of the thorax and the reference technique were almost perfect with a cutoff of 1 cm. The relative sensitivity of these two alternative techniques was high (> 93%).

CONCLUSION

Lung ultrasonography of the cranial + middle part or on the cranial part only of the thorax are quick and sensitive techniques to identify veal calves with lung consolidation lesions shortly after arrival at the facility.

Identification of bovine respiratory disease through the nasal microbiome

BACKGROUND

Bovine respiratory disease (BRD) is an ongoing health and economic challenge in the dairy and beef cattle industries. Multiple risk factors make an animal susceptible to BRD. The presence of Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis in lung tissues have been associated with BRD mortalities, but they are also commonly present in the upper respiratory tract of healthy animals. This study aims to compare the cattle nasal microbiome (diversity, composition and community interaction) and the abundance of BRD pathogens (by qPCR) in the nasal microbiome of Holstein steers that are apparently healthy (Healthy group, n = 75) or with BRD clinical signs (BRD group, n = 58). We then used random forest models based on nasal microbial community and qPCR results to classify healthy and BRD-affected animals and determined the agreement with the visual clinical signs. Additionally, co-occurring species pairs were identified in visually BRD or healthy animal groups.

RESULTS

Cattle in the BRD group had lower alpha diversity than pen-mates in the healthy group. Amplicon sequence variants (ASVs) from Trueperella pyogenes, Bibersteinia and Mycoplasma spp. were increased in relative abundance in the BRD group, while ASVs from Mycoplasma bovirhinis and Clostridium sensu stricto were increased in the healthy group. Prevalence of H. somni (98%) and P. multocida (97%) was high regardless of BRD clinical signs whereas M. haemolytica (81 and 61%, respectively) and M. bovis (74 and 51%, respectively) were more prevalent in the BRD group than the healthy group. In the BRD group, the abundance of M. haemolytica and M. bovis was increased, while H. somni abundance was decreased. Visual observation of clinical signs agreed with classification by the nasal microbial community (misclassification rate of 32%) and qPCR results (misclassification rate 34%). Co-occurrence analysis demonstrated that the nasal microbiome of BRD-affected cattle presented fewer bacterial associations than healthy cattle.

CONCLUSIONS

This study offers insight into the prevalence and abundance of BRD pathogens and the differences in the nasal microbiome between healthy and BRD animals. This suggests that nasal bacterial communities provide a potential platform for future studies and potential pen-side diagnostic testing.

Randomized field trial comparing the efficacy of florfenicol and oxytetracycline in a natural outbreak of calf pneumonia using lung reaeration as a cure criterion

Background

Respiratory infections are the main indication for antimicrobial use in calves. Optimal treatment duration currently is unknown, but shorter duration would likely decrease selection for antimicrobial resistance.

Hypothesis/Objectives

Determine differences in cure rate and healing time between animals treated with florfenicol and oxytetracycline in a natural outbreak of respiratory disease using reaeration observed on thoracic ultrasound examination as healing criterion.

Animals

Commercial farm housing 130, 3 to 9 month old Belgian blue beef calves.

Methods

Randomized clinical trial during an outbreak of respiratory disease. Metaphylactic treatment was initiated, randomly treating animals with either florfenicol or oxytetracycline. Ultrasonographic follow‐up was done the first day and every other day for a 14‐day period. At the individual animal level, treatment was discontinued when reaeration of the lungs occurred. Differences in cure rate and healing time were determined.

Results

Of the 130 animals studied, 67.7% developed a lung consolidation ≥0.5 cm. The mean ultrasonographic healing time was 2.5 days in the florfenicol group compared to 3.1 days in the oxytetracycline group (P = .04). After single treatment, 80.6% and 60.3% had no consolidations in the florfenicol and oxytetracycline groups, respectively (P = .01). A Mycoplasma bovis strain was genetically and phenotypically determined to be susceptible to both antimicrobials.

Conclusions and Clinical Importance

Ultrasonographic lung reaeration shows potential as a cure criterion to rationalize antimicrobial use for outbreaks of pneumonia. In our study, florfenicol resulted in a faster cure and higher reduction in antimicrobial usage than did oxytetracycline.

Use of Thoracic Ultrasonography to Improve Disease Detection in Experimental BRD Infection

Bovine respiratory disease (BRD) is caused by complex interactions between viral and bacterial pathogens, host immune status, and environmental stressors. In both clinical and research settings, current methods for detecting BRD in calves commonly focus on visual indicators such as attitude, nasal discharge, and cough, in addition to vital signs such as rectal temperature and respiration rate. Recently, thoracic ultrasonography (TUS) has become more commonly used in clinical settings, in addition to physical examination to diagnose BRD. To assess the value of performing TUS during experimental BRD infection, 32 calves were challenged with bovine respiratory syncytial virus, to mimic a viral infection, and 30 calves were infected with Mannheimia haemolytica, to mimic a bacterial infection. TUS was performed at regular intervals using a standardized method and scoring system in addition to daily clinical scoring. Although overall correlations between clinical scores and TUS scores were generally weak (maximum R2 = 0.3212), TUS identified calves with abnormal lung pathology that would have otherwise been misclassified on the basis of clinical scoring alone, both on arrival and throughout the studies. In addition, TUS had an increased correlation with gross lung pathology on necropsy (maximum R2 = 0.5903), as compared to clinical scoring (maximum R2 = 0.3352). Our results suggest that TUS can provide additional information on calf health at enrollment and throughout a study and may provide an alternative to terminal studies, due to the high correlation with lung pathology at necropsy.

Etiology and risk factors for bovine respiratory disease in pre-weaned calves on California dairies and calf ranches

Our study objective was to estimate the magnitude of association of BRD risk factors including failure of passive immunity transfer, sex, age, and the detection of suspected BRD etiological pathogens in pre-weaned dairy calves in California. A conditional logistic regression model and a mixed-effects logistic regression model were used to estimate the association of these potential risk factors with BRD from a matched and nested case-control studies, respectively. For each exposure covariate, the odds ratio (OR) is the ratio of odds of an exposure in a BRD calf (case) to that in a non-BRD calf (control). In the matched case-control study, an interaction term between failure of transfer of passive immunity and sex of calf showed that female calves were more negatively impacted by failure of transfer of passive immunity compared to male calves. The odds ratios comparing failure of transfer of passive immunity in BRD score positive calves versus controls for male calves was 1.34 (95 % CI: 0.87, 2.06) and was 2.47 (95 % CI: 1.54, 3.96) for female calves. The model odds ratios varied from 1.74 (95 % CI: 1.26, 2.42) for Mycoplasma spp. to 9.18 (95 % CI: 2.60, 32.40) for Histophilus somni, with Mannheimia haemolytica and Pasteurella multocida having an OR of 6.64 (95 % CI: 4.39, 10.03) and 6.53 (95 % CI: 4.44, 9.59), respectively. For bovine respiratory syncytial virus positive calves, the OR was 4.60 (95 % CI: 3.04, 6.97). Findings from the nested case-control study showed that based on thoracic ultrasonography findings consistent with BRD, the odds of a calf being 1 day older compared to a day younger were 1.01 (95 % CI: 1.00, 1.02) among BRD cases. For the bacterial and viral pathogens, the OR for Mycoplasma spp. and Pasteurella multocida were 1.85 (95 % CI: 1.24, 2.75) and 1.86 (95 % CI: 1.28, 2.71), respectively. The OR values for these pathogens were similar when both thoracic auscultation and ultrasound findings were used to detect cases of BRD. Based on positive scores for BRD using the California BRD scoring system, the OR for facility type, calf ranch versus dairy farm, was 3.17 (95 % CI: 1.43, 7.01), Mannheimia haemolytica was 3.50 (95 % CI: 2.00, 6.11), Pasteurella multocida was 1.78 (95 % CI: 1.21, 2.60), and bovine coronavirus was 2.61 (95 % CI: 1.85, 3.70). Results from both study designs showed the difference in relative contributions of age, sex, immune status, and pathogens in BRD occurrence between cases and controls in pre-weaned dairy calves.

BRD treatment failure: clinical and pathologic considerations

In cattle treated for respiratory disease, resolution of clinical signs has been the mainstay of determining treatment response and treatment efficacy. Through the use of calf lung ultrasound, we have found that pneumonia can persist or recur in the face of antibiotic therapy, despite improved clinical signs, leading to greater risk of clinical disease and more antibiotic use in the future. This review will discuss the pros and cons of using clinical signs to define resolution of disease and discuss how to implement lung ultrasound to improve our ability to accurately measure the impact of antibiotic therapy in cattle with respiratory disease.

Comparison of thoracic ultrasonography and thoracic radiography to detect active infectious bronchopneumonia in hospitalized dairy calves

Background

The best test between thoracic ultrasonography (TUS) and thoracic radiography (TR) or the best combination of tests (series or parallel) to detect active infectious bronchopneumonia (BP) in hospitalized dairy calves remains unknown.

Hypothesis/Objectives

To estimate performances of TUS and TR to detect active BP in hospitalized dairy calves and to determine the best strategy for using these tests based on a panel diagnosis method (PDM). Performances of TUS and TR were hypothesized to be equivalent.

Animals

Fifty hospitalized dairy calves (≥7 days old; ≤100 kg; standing; pCO₂ ≥ 53 mm Hg; any reason of presentation).

Methods

Each calf prospectively and sequentially underwent physical examination, thoracic auscultation, blood analyses, and TUS and TR. Three blinded experts determined whether active BP was present/absent based on PDM. Krippendorff's alpha measured interexpert agreement. The sensitivities (Se) and specificities (Sp) of TUS and TR alone and in series or parallel were compared (McNemar's test; P < .05).

Results

Interexpert agreement was moderate at 0.58 (95%CI: 0.42; 0.73). The Se and Sp of TUS were 0.84 (95%CI: 0.60; 0.97) and 0.74 (95%CI: 0.57; 0.86), respectively. The Se and Sp of TR were 0.89 (95%CI: 0.67; 0.99) and 0.58 (95%CI: 0.39; 0.75), respectively. No significant difference was found in the Se and Sp of TUS and TR when analyzed alone, in series or in parallel.

Conclusion

Thoracic ultrasonography or TR alone equally detected active BP in hospitalized dairy calves. Series or parallel analysis provided no additional benefit. Its ease of use and widespread accessibility support using TUS as a first‐line test to detect active BP in hospitalized dairy calves.

Short communication: Diagnostic accuracy of focused lung ultrasonography as a rapid method for the diagnosis of respiratory disease in dairy calves

This study estimates the accuracy of the focused lung ultrasound (FLUS) compared with systematic thoracic ultrasonography (TUS) as the reference test for diagnosing pneumonia in pre- and postweaned dairy calves. One hundred thirty-five Holstein Friesian calves, aged between 1 to 6 mo were enrolled and were kept in the same pen with one or more animals showing signs of bovine respiratory disease complex (BRDC). One operator performed FLUS on each calf, and then a second, blinded operator performed TUS on the same calf. For the FLUS, we only scanned the lung lobes that are most frequently affected during BRDC and are thus easier to detect, such as the caudal aspect of the cranial lobe of the left lung (fifth and fourth left intercostal spaces; ICS), the middle lobe of the right lung (fifth right ICS), and the caudal aspect of the cranial lobe of the right lung (fourth right ICS). Pneumonia was diagnosed when a calf had a minimum of one small lobular lung lesion that was at least 1 cm deep within a normally aerated lobe (TUS score of ≥2). Diagnostic accuracy indexes of the FLUS were calculated using TUS as the gold standard. The McNemar test was performed to evaluate the differences between the 2 techniques. In addition, an intertest agreement was assessed using the weighted kappa test. A total of 76 out of 135 calves had a TUS score of ≥2 and were therefore considered to be affected by BRDC. The FLUS had a sensitivity of 81.6% (95% CI = 71.0-89.5%), specificity = 100% (95% CI = 93.9-100%), positive predictive value was 100%, negative predictive value was 96.6% (95% CI = 94.7---97.9%), and accuracy was 97% (95% CI = 92.6-99.2%). The McNemar test highlighted a difference of 10.3% between the FLUS and TUS. The agreement between the TUS and FLUS was substantial (weighted kappa test 0.78). Although FLUS shows some limitations in diagnosing lung lesions associated with BRDC compared with the systematic approach, this study shows that the focused method could be used as an additional tool for evaluating consolidation, especially when examining a large number of postweaned dairy calves.

The nasopharyngeal microbiota of preweaned dairy calves with and without ultrasonographic lung lesions

The primary objective of this cross-sectional study was to identify associations between the diversity and composition of the nasopharyngeal (NP) microbiota and pneumonia status, as diagnosed by ultrasonography (US), in preweaned dairy calves. Characteristics of the NP microbiota were compared between calves with and without pneumonia, as diagnosed by US. Secondary objectives were to compare the composition of the NP microbiota between calves by age, clinical respiratory score (CRS), and previous antibiotic therapy. Holstein heifer calves (n = 50) from a southern Wisconsin dairy were enrolled at either 3 or 6 wk of age; 4 calves were sampled at both time points. Antibiotic treatment history was also collected for the 30 d before enrollment. For the purpose of this study, pneumonia was defined as having lobar pneumonia, as diagnosed by US, in at least 1 lung lobe. Following examination by CRS and US, a deep nasopharyngeal swab was obtained for 16S rRNA amplicon sequencing. Alpha diversity was reduced in calves that were CRS positive, and beta diversity tended to be different in calves previously treated with antibiotics and in calves that were CRS positive. Microbial diversity was not different between calves with and without pneumonia. The most dominant genus identified was Mycoplasma spp.; however, there was no association between relative abundance (RA) and pneumonia status. The median RA of Mycoplasma spp. was increased by 25 (95% confidence interval, CI: 3, 40) in calves at 3 wk of age compared with 6 wk of age. The median RA of Pasteurella spp. was increased by 1.5 (95% CI: 0.1, 3) in calves with pneumonia, as diagnosed by US, compared with calves without pneumonia. Additionally, Pasteurella spp. was increased by 2.3 (95% CI: 0, 9) in CRS-positive calves compared with CRS-negative calves. The median RA of Psychrobacter spp. was increased by 2 (95% CI: 0, 12) and median RA of Chryseobacterium spp. was increased by 0.15 (95% CI: 0, 2) in calves that were not treated previously with antibiotics compared with calves previously treated with antibiotics.

Particulate matter and airborne endotoxin concentration in calf barns and their association with lung consolidation, inflammation, and infection

Agricultural operations are important sources of organic dust containing particulate matter (PM) and endotoxins, which have possible negative health consequences for both humans and animals. Dust concentrations and composition in calf barns, as well as the potential health effects for these animals, are scarcely documented. The objective of this study was to measure PM fractions and endotoxin concentrations in calf barns and study their associations with lung consolidation, respiratory tract inflammation, and infection in group-housed calves. In this cross-sectional study, samples from 24 dairy farms and 23 beef farms were collected in Belgium from January to April 2017. PM_1.0, PM_2.5 and PM₁₀ (defined as particulate matter passing through a size-selective inlet with a 50% efficiency cut-off at a 1.0-μm, 2.5-μm, and 10-μm aerodynamic diameter, respectively) were sampled during a 24-h period using a Grimm aerosol spectrometer (Grimm Aerosol Technik Ainring GmbH & Co. KG). Endotoxin concentration was measured in the PM₁₀ fraction. Thoracic ultrasonography was performed and broncho-alveolar lavage fluid was collected for cytology and bacteriology. Average PM concentrations were 16.3 µg/m³ (standard deviation, SD: 17.1; range: 0.20-771), 25.0 µg/m³ (SD: 25.3; range: 0.50-144.9), and 70.3 µg/m³ (SD: 54.5; range: 1.6-251.2) for PM_1.0, PM_2.5, and PM₁₀, respectively. Mean endotoxin in the PM₁₀ fraction was 4.2 endotoxin units (EU)/µg (SD: 5.50; range: 0.03-30.3). Concentrations in air were 205.7 EU/m³ (SD: 197.5; range: 2.32-901.0). Lung consolidations with a depth of ≥1, ≥3, and ≥6 cm were present in 43.1% (146/339), 27.4% (93/339), and 15.3% (52/339) of the calves, respectively. Exposure to fine (PM_1.0) PM fractions was associated with increased odds of lung consolidations of ≥1 cm (odds ratio, OR: 3.3; confidence interval (CI): 1.5-7.1), ≥3 cm (OR: 2.8; CI: 1.2-7.1), and ≥6 cm (OR: 12.3; CI: 1.2-125.0). The odds of having lung consolidations of ≥1 cm (OR: 13.9; CI: 3.4-58.8) and ≥3 cm (OR: 6.7; 1.7-27.0) were higher when endotoxin concentrations in the dust mass exceeded 8.5 EU/µg. Broncho-alveolar lavage fluid neutrophil percentage was positively associated with PM₁₀ concentration, and epithelial cell percentage was negatively associated with this fraction. Concentration of PM_2.5 was positively associated with epithelial cell percentage and isolation of Pasteurella multocida. Although concentrations of fine dust are lower in calf barns than in poultry and pig housings, in this study they were associated with pneumonia in calves. Dust control strategies for reducing fine dust fractions in calf barns may benefit human and animal respiratory health.

Growth performance and hematological changes of weaned beef calves diagnosed with respiratory disease using respiratory scoring and thoracic ultrasonography

This study investigated 1) the effect of clinical bovine respiratory disease (BRD) and associated lung consolidations on growth performance and hematological profiles of recently weaned beef calves and 2) the relationship between clinical respiratory signs and lung consolidation detected by thoracic ultrasonography (TUS). One hundred and fifty-three weaned beef calves (209 days old [SD: 35.8] and 306 kg [SD: 26.3], at arrival) purchased and transported from auction markets were accommodated indoors in concrete slatted floor pens. Calves were weighed weekly from arrival until day 28 and on day 65 post-arrival. Assessment of BRD and blood sample collection for hematological profiles were performed on scheduled days (at arrival, on days 7, 14, and 28) and on other days upon BRD diagnosis. Animals were assessed for BRD using a total clinical respiratory score (CRS) of five clinical signs (rectal temperature, ear position, cough, nasal secretion, and eye secretion with each ranging from normal [0] to abnormal [3]) and TUS scores (normal [0] to lung consolidation ≥ 1 cm2 [2]). Based on CRS, 35% of calves were CRS+ (CRS ≥ 5) and 65% were CRS- (CRS < 5). Although no lung consolidations (TUS-) were detected at arrival, 34% of calves developed lung consolidation (≥1 cm2) (TUS+) during the first 28 d post-arrival. Only fever (>39.6 °C) and nasal discharge were weakly associated (r = 0.19, P <0.05) with lung consolidation. On the day of BRD detection, neutrophil number and neutrophil:lymphocyte ratio were 58% and 73% greater, respectively, in BRD calves with lung consolidation compared with healthy calves. From day 0 to 65, calf average daily gain (ADG) did not differ (P >0.05) between CRS+ and CRS- calves but was 0.09 kg/d lower (P < 0.05) for TUS+ compared with TUS- calves. Calves classified as BRD (CRS + TUS ≥ 5) with lung consolidation had lower (P < 0.05) ADG from arrival until day 28 than healthy calves and BRD calves without lung consolidation (0.11 ± 0.10 vs. 0.53 ± 0.07 vs. 0.57 ± 0.10 kg/d, respectively); however, no differences in ADG were observed from day 0 to 65. Conventional methods to diagnose BRD failed to detect calves with lung lesions. TUS is a useful tool to detect lung lesions and its implementation in combination with CRS should provide a more accurate and early diagnosis of BRD, which is fundamental to successful treatment, animal welfare, and growth performance.