Comparison of thoracic auscultation, clinical score, and ultrasonography as indicators of bovine respiratory disease in preweaned dairy calves

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.

Electrical impedance tomography in calves with bovine respiratory disease: correlations with clinical and blood gas findings

Bovine respiratory disease (BRD) is a multifactorial global problem associated with long-term deleterious effects on the well-being of calves and marked financial losses. Prompt diagnosis of BRD, monitoring the success of treatment, and providing an accurate prognosis remain challenging because current methods for stall-side diagnosis are inadequate. To improve diagnosis in addition to clinical and morphological findings and gain insight into the respiratory dynamics of BRD, thoracic electrical impedance tomography (EIT) was used to evaluate calves with BRD (Group D; n = 42) and healthy calves (Group H; n = 13). Thoracic EIT is a non-invasive method of quantifying differences in impedance changes between various lung regions and impedance changes over time. A belt with 32 equidistantly mounted electrodes was placed around the thorax of non-sedated calves of both groups to measure impedance changes during respiration. The results were compared with the clinical findings and the California BRD scores. Compared with group H, Group D had decreased ventilation in the ventral lung regions (p = 0.05); ventilation shifted to the left lung lobes in calves with marked auscultatory changes (p = 0.013). In addition, the quartile ventilation ratio on inspiration (VQRi), used to quantify changes in impedance during inspiration, differed significantly between the two groups (p = 0.0039). Of all the EIT parameters, VQRi correlated most closely with paO2 and the A-a-gradient and was significantly lower in group D than in group H (p = 0.061). The results of EIT revealed differences in the inspiratory dynamics of clinically healthy and ill calves and correlated with the clinical and blood gas findings. Thus, EIT can be used alone or together with other diagnostic tools to identify and monitor BRD 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.

Optimizing respiratory vaccination strategies for Jersey calves: Impact of timing and maternal antibody interference

Bovine Respiratory Disease (BRD) poses a significant challenge to the cattle industry, as it causes substantial economic losses and adverse impacts on animal welfare. This study aimed to determine the optimal timing for respiratory vaccination in Jersey calves, considering age-related responses and maternal antibody interference. Twenty-five Jersey calves were randomly assigned to three vaccination groups based on timing: Group A (14 and 16 weeks), Group B (16 and 18 weeks), and Group C (18 and 20 weeks). Calves were further divided into subgroups based on their initial Infectious Bovine Rhinotracheitis (IBR) antibody levels. Blood samples were collected at 8, 14, 24, and 52 weeks of age to measure IBR and Bovine Viral Diarrhea (BVD) antibody levels. The results indicated that the vaccination strategy, which considered maternal IBR antibody levels at the time of vaccination, enhanced long-term IBR immunity and influenced BVD immunity. Additionally, calves vaccinated while seronegative for IBR exhibited higher seropositivity at 52 weeks compared to those immunized while seropositive. Our findings suggest that the optimal vaccination strategy for Jersey calves involves primary vaccination between 14 and 18 weeks of age, followed by a booster shot at a two-week interval. Furthermore, low maternal anti-IBR antibody levels at the time of vaccination were associated with increased antibody levels at 52 weeks of age and may influence BVD immunity. These findings could inform the development of more effective vaccination strategies for Jersey calves, potentially enhancing BRD management and reducing the economic impact on this breed.

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.

Associations Between Thoracic Ultrasound Chute-Side Evaluations and 60-Day Outcomes in Feedyard Cattle at Time of First Treatment for Respiratory Disease

Accurate prognosis at first treatment for bovine respiratory disease (BRD) is essential for timely interventions and management decisions. This cross-sectional observational study evaluated 819 commercial beef feedyard cattle at chute-side for first BRD treatment. Logistic regression models examined potential associations between two outcomes-first treatment failure (requiring additional treatment) and unfinished treatment (due to mortality or culling)-and several explanatory variables, including sex, days on feed, bodyweight, breed, pulse oximetry, lung auscultation scores, and ultrasound lung scores (ULS) measured in the caudo-dorsal lung region. Animals that ultimately did not finish treatment were significantly more likely to present a ULS of 5 (74%) compared with those scored 1-4 (18-38%). Similarly, cattle with a ULS of 5 had a much higher probability of first treatment failure (74%) than those with scores of 1-3 (35-41%). Moreover, three or more B-lines in the ultrasound image or a "moth sign" finding were both strongly associated with increased probability of negative outcomes. These results highlight key ultrasound-based and demographic factors that serve as practical prognostic indicators for cattle at the onset of BRD treatment.

Identification of diagnostic biomarkers of and immune cell infiltration analysis in bovine respiratory disease

Background

Bovine respiratory disease (BRD) is a prevalent and costly condition in the cattle industry, impacting long-term productivity, antibioticusage, and global food safety. Thus, identifying reliable biomarkers for BRD is crucial for early diagnosis, effective treatment, and monitoring therapeutic outcomes.

Methods

This study identified differentially expressed genes (DEGs) associated with BRD by analyzing a blood RNA-seq expression dataset associated with BRD, and conducted a Kyoto Encyclopedia of Genes and Genomes (KEGG) approach enrichment and Gene Ontology (GO) annotation analysis on these DEGs. Meanwhile, the key modules related to BRD were screened by weighted gene co-expression network analysis (WGCNA), and the genes in the module were intersected with DEGs. Subequently, least absolute shrinkage and selection operator (LASSO) and random forest (RF) analysis were employed to identify potential biomarkers. Finally, gene set enrichment analysis (GSEA) was performed to explore the potential mechanisms of the identified biomarkers, and their diagnostic significance was assessed using receiver operator characteristic (ROC) curve analysis and real-time fluorescent quantitative PCR (RT-qPCR). In addition, immune cell infiltration in BRD was evaluated using the CIBERSORT algorithm and the correlation between biomarkers and immune cell infiltration was analyzed.

Results

The results showed that a total of 1,097 DEG were screened. GO and KEGG analysis showed that DEGs was mainly enriched in inflammatory response, defense response, Complement and coagulation cascades and Antigen processing and presentation pathways. WGCNA analysis determined that the cyan module had the highest correlation with BRD. A total of 833 overlapping genes were identified through Venn analysis of the differential and WGCNA results. Lasso and RF analyses identified five potential biomarkers for BRD. RT-qPCR testing and data set analysis showed that the expression levels of these five potential biomarkers in nasal mucus and blood of BRD cattle were significantly higher than those of healthy cattle. In addition, ROC curve analysis showed that potential biomarkers had high diagnostic value. GSEA analysis revealed that potential biomarkers are mainly involved in Neutrophil extracellular trap formation, Complement and coagulation cascades, T cell receptor signaling pathway, B cell receptor signaling pathway, Fc gamma R-mediated phagocytosis and IL-17 signaling pathway. The results from the CIBERSORT algorithm demonstrated a significant difference in immune cell composition between the BRD group and the healthy group, indicating that the diagnostic biomarkers were closely associated with immune cells.

Conclusion

This study identified ADGRG3, CDKN1A, CA4, GGT5, and SLC26A8 as potential diagnostic markers for BRD, providing significant insights for the development of new immunotherapy targets and improving disease prevention and treatment strategies.

The Effect of Florfenicol Given by Nebulization in the Treatment of Naturally Infected Calves With Bovine Respiratory Disease Complex: Randomized Clinical Study

BACKGROUND

Bovine respiratory disease (BRD) is still one of the major problems for herd management due to the negative effects on herd health, costs due to treatment, reduced weight gain and calf loss. The aim of this study is to evaluate the effectiveness of aerosolized florfenicol in calves with naturally infected BRD.

METHODS

Forty-five calves were included in the study and divided into three groups. Group 1 received florfenicol subcutaneous route. While Group 2 received florfenicol administered solely through nebulization, Group 3 received florfenicol via nebulization in addition to flunixin meglumine administered intramuscularly (IM). BRD pathogens were determined from bronchoalveolar lavage (BAL) samples. The treatment period was monitored with a clinical respiratory score, haematology, thorax ultrasonography and serum haptoglobin levels.

RESULTS

Mycoplasma bovis was the main primary bacterial pathogen isolated from BAL fluid, Escherichia coli was the main secondary bacterial pathogen and bovine respiratory syncytial virus (BRSV) was found to be the primary viral BRD pathogen. The treatment period was shortened to the 2nd day in the groups with nebulization. Calves with clinical respiratory scores of 12 and above died in all groups. There was no significant difference in lung ultrasonographic scoring and haematology results before and after treatment within the groups. There was a significant decrease in the high haptoglobin values before and after the 3rd day of treatment. The study's main limitation was that there was no negative control group in this study due to ethical reasons.

CONCLUSION

It was concluded that florfenicol administered by inhalation in BRD patients is more effective, reduces the recovery time and will be a promising treatment strategy.

Comparative evaluation of lower respiratory tract microbiota in healthy and BRD-affected calves in Egypt

The advent of next-generation sequencing technologies has uncovered the importance of commensal microbial populations in the lower respiratory tract (LRT) for mucosal health and their role in the development of bovine respiratory disease (BRD). In this study, we aimed to characterize and compare the LRT microbiota in healthy and BRD-affected calves in Egypt. After assessing clinical respiratory scores in both groups, post-mortem lung samples from the cranial lobes of six clinically healthy calves and six calves affected by BRD were collected following slaughter. The most prevalent bacterial families in all samples were Moraxellaceae (11.06%), Enterobacteriaceae (8.23%), and Flavobacteriaceae (8.13%). The most common bacterial genera across all samples were Acinetobacter (13.1%), Gracilibacillus (7.9%), and Pseudomonas (5.0%). Notably, the overall microbial community structures differed significantly between healthy and BRD-affected calves. Alpha diversity analysis revealed significant differences in the Shannon (p = 0.0043) and Chao1 (p = 0.0001) indices between the two groups. This study highlights the substantial impact of BRD on the LRT microbiota of calves, highlighting the intricate relationship between host health and the LRT microbial ecosystem. Further investigations involving a larger sample size are necessary to establish the clinical significance of LRT microbiota in maintaining bovine respiratory health.

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.

Thoracic Ultrasound in Cattle: Methods, Diagnostics, and Prognostics

Thoracic ultrasonography (TUS) has emerged as a critical tool in the diagnosis and management of respiratory diseases in cattle, particularly bovine respiratory disease (BRD), which is one of the most economically significant health issues in feedyard operations. The objective of this review is to explore TUS in veterinary medicine, including the historical development, methodologies, and clinical applications for diagnosing and prognosing respiratory diseases. This review also emphasizes the importance of operator training, noting that even novice operators can achieve diagnostic consistency with proper instructions. Ultrasound was introduced in the mid-20th century for back-fat thickness measurements; TUS has evolved to offer a non-invasive, real-time imaging modality that allows for the detection of lung and pleural abnormalities such as consolidations, pleural effusions, and B-lines. These features are vital indicators of respiratory disease, and their early identification through TUS can significantly improve clinical outcomes. Compared to traditional diagnostic methods like auscultation or radiography, TUS provides superior accuracy in detecting both subclinical and advanced respiratory conditions, particularly in high-risk populations. Furthermore, TUS has demonstrated strong prognostic value, with studies showing that the extent of lung consolidation correlates with higher relapse risk, reduced growth performance, and increased mortality.

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.

Determining the Effect of Varied Proportions of Cohort Administered Tulathromycin at Arrival on Nasopharyngeal Microbiota and Performance Characteristics in Yearling Steers in the First 56 Days on Feed

Metaphylaxis or treating the entire population of cattle at arrival with an antimicrobial has been studied extensively in the cattle industry; however, little information is available on the impacts of treating only a proportion of the population with antimicrobials at arrival. The study objective was to determine potential associations between the proportion of animals in a pen treated with antimicrobial therapy with pen performance and nasopharyngeal microbiome. Yearling steers (n = 160) were randomly allocated to study pens (n = 40) and pens were systematically randomized to one of two antimicrobial treatments (META: all four head received tulathromycin; MIXED: two of four head randomly selected to receive tulathromycin). The study was conducted in conjunction with an essential oil feeding trial. Deep nasal pharyngeal (DNP) swabs were collected from every steer at Days 0, 14, 28, and 56. All DNP swabs were individually cultured for Pasteurella multocida and Mannheimia haemolytica. Samples of DNA were extracted from DNP swabs, pooled by pen, and analyzed by metagenomic shotgun sequencing to compare nasopharyngeal microbiome composition and quantity of resistance genes between test groups. Neither antimicrobial nor essential oil treatment groups had any significant associations with performance or DNP microbiome. Sampling day was significantly associated with alpha and beta diversity at the species level. Shannon's diversity and Inverse Simpson diversity were significantly lower on Day 14 versus both Day 0 and Day 56. These data indicated a shift in microbial populations across study days; however, the microbiome diversity and relative abundance were not significantly different between antimicrobial treatment groups.

Harnessing uncertainty: A deep mechanistic approach for cautious diagnostic and forecast of Bovine Respiratory Disease

Bovine Respiratory Disease (BRD) is a prevalent infectious disease of respiratory tract in cattle, presenting challenges in accurate diagnosis and forecasting due to the complex interactions of multiple risk factors. Common methods, including mathematical epidemiological models and data-driven approaches such as machine learning models, face limitations such as difficult parameter estimation or the need for data across all potential outcomes, which is challenging given the scarcity and noise in observing BRD processes. In response to these challenges, we introduce a novel approach known as the Bayesian Deep Mechanistic method. This method couples a data-driven model with a mathematical epidemiological model while accounting for uncertainties within the processes. By utilising 265 lung ultrasound videos as sensor data from 163 animals across 9 farms in France, we trained a Bayesian deep learning model to predict the infection status (infected or non-infected) of an entire batch of 12 animals, also providing associated confidence levels. These predictions, coupled with their confidence levels, were used to filter out highly uncertain diagnoses and diffuse uncertainties into the parameterisation of a mathematical epidemiological model to forecast the progression of infected animals. Our findings highlight that considering the confidence levels (or uncertainties) of predictions enhances both the diagnosis and forecasting of BRD. Uncertainty-aware diagnosis reduced errors to 32 %, outperforming traditional automatic diagnosis. Forecast relying on veterinarian diagnoses, considered the most confident, had a 23 % error, whilst forecast taking into account diagnosis uncertainties had a close 27.2 % error. Building upon uncertainty-awareness, our future research could explore integrating multiple types of sensor data, such as video surveillance, audio recordings, and environmental parameters, to provide a comprehensive evaluation of animal health, employing multi-modal methods for processing this diverse data.

Cross-sectional study: can endogenous procalcitonin differentiate between healthy and bovine respiratory disease-affected preweaned dairy calves?

Bovine respiratory disease (BRD) represents a significant challenge in cattle management due to its multifactorial nature and lack of a gold standard diagnostic method. Procalcitonin (PCT) has emerged as a potential biomarker for bacterial infections in various species, including cattle. This study aimed to investigate plasma PCT concentration variations in pre-weaned dairy calves categorized as BRD-positive using clinical scores (WRSC; BRD-positive ≥5), thoracic ultrasonography with two cut-off (TUS; BRD-positive ≥1 or ≥3), or a combination of both methods (WRSC/TUS1cm or WRSC/TUS3cm). Additionally, the accuracy of PCT in diagnosing BRD was evaluated. A cross-sectional study was conducted on a convenience sample of 226 pre-weaned Italian-Friesian female calves. Clinical scoring, TUS, and plasma PCT analysis were performed. Calves were categorized based on TUS findings, clinical scores, or a combination of both methods. Statistical analyses were conducted to assess the differences in PCT concentrations among different groups and to determine the diagnostic accuracy of PCT. Results showed a significant increase in PCT levels in calves with lung consolidation detected by TUS using a 1 cm cutoff. However, the diagnostic accuracy of PCT in discriminating BRD-positive cases was poor (area under the curve 0.62). The optimal cutoff value for PCT was determined to be 86.63 pg/mL, with sensitivity of 49.7%, specificity of 71.8%, positive predictive value of 79.4% and negative predictive value of 39.5%. In conclusion, while PCT showed potential as a biomarker for BRD, its diagnostic accuracy was limited in this study. Future research should focus on integrating PCT measurements with other diagnostic methods and conducting longitudinal cohort studies to better understand its role in BRD diagnosis and management.

Are you ready for a challenge? Personality traits influence dairy calves' responses to disease, pain, and nutritional challenges

Dairy calves routinely experience disease, pain, and nutritional stressors such as diarrhea, dehorning, and weaning early in life. These stressors lead to changes in behavioral expression that varies in magnitude between individuals, where a greater magnitude change would suggest lower resilience in individuals to a stressor. Thus, this study first aimed to quantify the individual variation in magnitude change in feeding behaviors and activity in response to a bout of diarrhea, dehorning, and weaning. The next objective was to then investigate if personality traits were related to this magnitude of behavioral response in dairy calves, and thus their resilience toward these stressors. Calves were followed with 2 precision livestock technologies (e.g., an automatic feeding system, and leg accelerometer) to track behavioral changes in response during the time when the stressors were present. The automatic feeding system provided daily measures of milk intake, drinking speed, rewarded and unrewarded visits to the milk feeding station, and calf starter intake. The leg accelerometer provided daily measures of steps, activity index, lying time, and lying bouts. At 23 ± 3 d of age, Holstein dairy calves (n = 49) were subjected to a series of standardized personality tests that exposed the calf to novelty and fear stimuli. Factors extracted from a principal component analysis on the behaviors from the personality test were interpreted as personality traits: Factor 1 (fearful), Factor 2 (active) and Factor 3 (explorative). The magnitude changes in behaviors from the precision livestock technologies were calculated relative to the behavior performed on the day the stressor occurred (i.e., day of diagnosis, day of dehorning, day weaned). Linear regression models were used to determine whether calf scores on each factor were associated with magnitude change in behavior for each of the stressor periods with day relative to the stressor included as a repeated measure. Models were run independently for the period leading up to and following each stressor. We found that calves varied in their behavioral responses to diarrhea, dehorning, and weaning stressors, despite being reared in the same environment and experiencing consistent management procedures. Additionally, personality traits measured from standardized tests were associated with both the direction and magnitude of change in behaviors around each stressor. For instance, with diarrhea, calves that were highly fearful had a greater magnitude change in milk intake and drinking speed following diagnosis than the least fearful calves. With dehorning, calves that were highly explorative had a greater magnitude change in lying time when dehorned, but a smaller magnitude change in lying bouts and drinking speed following dehorning, compared with the least explorative calves. With weaning, calves that were highly active had a smaller magnitude change in unrewarded visits leading up to and following weaning than calves that were the least active. Each of the personality traits had a significant association with change in behavior surrounding each of the stressors evaluated, although these associations depended on the type of stressor. These results have implications for how individual calves experience each stressor and therefore individual animal welfare.

Assessing lung consolidation in goats using different ultrasonographic techniques

Goats are often affected by respiratory diseases and, despite ultrasonography can assess lung consolidations in several species, it is rarely used in these animals. So, this study evaluated the effectiveness of on-farm lung ultrasonography in detecting lung consolidations on 27 goats. The goats, scheduled for slaughter, underwent complete clinical examinations and lung ultrasonography. For the latter, both sides of the thorax were divided in four quadrants and examined using convex and linear probes before and after shaving the hair. Each quadrant was classified based on presence/absence of lung consolidation and maximum consolidation's depth (4-point scale: 0 healthy; 1 depth < 1 cm; 2 depth < 3 cm; 3 depth > 3 cm). The lungs were examined at necropsy, 66% of goats exhibited lung consolidations and sensitivity (83%-89%), specificity (100%), and κ coefficient values (0.67-0.72) were high with all techniques. An higher (p ≤ 0.01) percentage of class 1 lesions were found at necropsy compared to all the ultrasonographic techniques. All the ultrasonographic techniques effectively detected lung consolidation deeper than 1 cm. So, ultrasonography seems an effective tool for lung examination in goats with chronic pneumonia. The examination using the linear or the convex probes without shaving the hair could be a promising tool for the on-field diagnosis of pneumonia, although further research on larger sample sizes are necessary to validate these findings.

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.

Performance of various interpretations of clinical scoring systems for diagnosis of respiratory disease in dairy calves in a temperate climate using Bayesian latent class analysis

Bovine respiratory disease (BRD) presents a challenge to farmers all over the globe, not only because it can have significant impacts on welfare and productivity, but also because diagnosis can prove challenging. Several clinical scoring systems have been developed to aid farmers in making consistent early diagnosis, 2 examples being the Wisconsin (WCS) and the California (CALIF) systems. Neither of these systems were developed in or for use in a temperate environment. As environment may lead to changes in BRD presentation, the weightings and cutoffs designed for one environmental presentation of BRD may not be appropriate when used in a temperate climate. Additionally, the interpretation of the scores recorded varies between studies; this may also influence conclusions. Hence, the objective of this work was to investigate the sensitivity (Se) and specificity (Sp) of these tests in a temperate climate and investigate the influence of varying the interpretation on the performance of the WCS. In this prospective study, 98 commercial spring-calving dairy farms were recruited (40 randomly, 58 targeted) and visited. Thoracic ultrasound and WCS were performed on 20 randomly sampled calves between 4 and 6 wk of age on each farm. On a subset of 32 farms, the CALIF score was also undertaken. The data were then used in a hierarchical Bayesian latent class model to estimate the Se and Sp of 5 different interpretations of the Wisconsin clinical score and 1 interpretation of the California clinical score. In total, 1,936 calves were examined. The Se of the Wisconsin score varied from 0.336 to 0.577 depending on the interpretation used, and the Sp varied from 0.943 to 0.977. The Se of the California score was 0.563 (95% Bayesian credible interval [BCI]: 0.452, 0.681) and the Sp was 0.919 (95% BCI: 0.899, 0.937). In conclusion, the performances of the clinical scores in a temperate environment were similar to previously published work from more extreme climates; however, the performance varied widely depending on the score interpretation. Authors should justify their use of a particular clinical score interpretation to improve clarity in publications.

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).

Early detection of bovine respiratory disease in pre-weaned dairy calves using sensor based feeding, movement, and social behavioural data

Previous research shows that feeding and activity behaviours in combination with machine learning algorithms has the potential to predict the onset of bovine respiratory disease (BRD). This study used 229 novel and previously researched feeding, movement, and social behavioural features with machine learning classification algorithms to predict BRD events in pre-weaned calves. Data for 172 group housed calves were collected using automatic milk feeding machines and ultrawideband location sensors. Health assessments were carried out twice weekly using a modified Wisconsin scoring system and calves were classified as sick if they had a Wisconsin score of five or above and/or a rectal temperature of 39.5 °C or higher. A gradient boosting machine classification algorithm produced moderate to high performance: accuracy (0.773), precision (0.776), sensitivity (0.625), specificity (0.872), and F1-score (0.689). The most important 30 features were 40% feeding, 50% movement, and 10% social behavioural features. Movement behaviours, specifically the distance walked per day, were most important for model prediction, whereas feeding and social features aided in the model's prediction minimally. These results highlighting the predictive potential in this area but the need for further improvement before behavioural changes can be used to reliably predict the onset of BRD in pre-weaned calves.

Comparison of physiological markers, behavior monitoring, and clinical illness scoring as indicators of an inflammatory response in beef cattle

Clinical illness (CI) scoring using visual observation is the most widely applied method of detecting respiratory disease in cattle but has limited effectiveness in practice. In contrast, body-mounted sensor technology effectively facilitates disease detection. To evaluate whether a combination of movement behavior and CI scoring is effective for disease detection, cattle were vaccinated to induce a temporary inflammatory immune response. Cattle were evaluated before and after vaccination to identify the CI variables that are most indicative of sick cattle. Respiratory rate (H2 = 43.08, P < 0.0001), nasal discharge (H2 = 8.35, P = 0.015), and ocular discharge (H2 = 16.38, P = 0.0003) increased after vaccination, and rumen fill decreased (H2 = 20.10, P < 0.0001). Locomotor activity was measured via leg-mounted sensors for the four days preceding and seven days following vaccination. A statistical model that included temperature, steps, lying time, respiratory rate, rumen fill, head position, and excess saliva was developed to distinguish between scores from before and after vaccination with a sensitivity of 0.898 and specificity of 0.915. Several clinical illness signs were difficult to measure in practice. Binoculars were required for scoring respiratory rate and eye-related metrics, and cattle had to be fitted with colored collars for individual identification. Scoring each animal took up to three minutes in a small research pen; therefore, technologies that can automate both behavior monitoring and identification of clinical illness signs are key to improving capacity for BRD detection and treatment.

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.

Comparative diagnoses of respiratory disease in preweaned dairy calves using sequential thoracic ultrasonography and clinical respiratory scoring

AIMS

Bovine respiratory disease (BRD) has serious impacts on dairy production and animal welfare. It is most commonly diagnosed based on clinical respiratory signs (CRS), but in recent years, thoracic ultrasonography (TUS) has emerged as a diagnostic tool with improved sensitivity and specificity. This study aimed to assess the alignment of BRD diagnoses based on a Clinical Respiratory Scoring Chart (CRSC) and weekly TUS findings throughout the progression of BRD of variable severity in preweaned Holstein dairy heifers.

METHODS

A total of 60 calves on two farms were followed from the 2nd week of life through the 11th week of life and assessed on a weekly basis for CRS and lung consolidation via TUS. The alignment of BRD diagnoses based on CRSC scores and TUS findings was evaluated across disease progression (pre-consolidation, onset, chronic, or recovered) and severity (lobular or lobar lung consolidation) using receiver operator curves and area under the curves combined with Cohen's kappa (κ), sensitivity, and specificity.

RESULTS

The diagnosis of BRD using CRSC scores ≥5 aligned best with the onset of lobar lung consolidation (>1 cm in width and full thickness). This equated to an acceptable level of discrimination (AUC = 0.76), fair agreement (κ = 0.37), and a sensitivity of 29% and specificity of 99%. Similarly, there was acceptable discrimination (AUC = 0.70) and fair agreement (κ = 0.33) between CRSC ≥5 and the onset of a less severe threshold of disease based on lobular (1-3 cm2 but not full thickness) or lobar consolidation. Discrimination remained acceptable (AUC = 0.71) with fair agreement (κ = 0.28) between CRSC scores ≥2 for nasal discharge and/or cough (spontaneous or induced) and the onset of lobar consolidation. However, sensitivity was <40% across comparisons and outside of the onset of disease there tended to be poor discrimination, slight agreement, and lowered sensitivity between CRS and TUS diagnoses of lobular or lobar consolidation (pre-consolidation, chronic, or recovered). Conversely, specificity was relatively high (≥92%) across comparisons suggesting that CRSC diagnoses indicative of BRD and associated lung consolidation tend to result in few false positive diagnoses and accurate identification of healthy animals.

CONCLUSIONS AND CLINICAL RELEVANCE

Although we found the specificity of clinical signs for diagnosing lung consolidation to be ≥92% across all methods of TUS evaluations, the low levels of sensitivity dictate that clinical assessments lead to many false negative diagnoses. Consequently, depending on clinical signs alone to diagnose BRD within populations of dairy calves will likely result in overlooking a substantial proportion of subclinically affected animals that could inform the success of treatment and prevention protocols and guide management decisions.

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.

Comparison and interobserver reliability between a visual analog scale and the Wisconsin Calf Health Scoring Chart for detection of respiratory disease in dairy calves

Respiratory disease is an ongoing challenge for calves in the dairy sector with a relatively high prevalence and impact on welfare and economics. Applying scoring protocols for detecting respiratory disease requires that they are easily implemented, consistent between observers and fast to use in daily management. This study was conducted in one Danish dairy farm from September 2020 through January 2021. The study included 126 heifer calves enrolled in the age of 17 to 24 d. All calves were observed every second day for a period of 46 d. At each visit all calves were scored with a new visual analog scale (VAS) and the Wisconsin Calf Health Scoring Chart (WCHSC). We calculated agreement between the 2 scoring systems based on conditional probability to score higher or lower than a cutoff in the VAS compared with a specified cutoff in WCHSC used as reference test. A generalized mixed effects regression model was developed to estimate the prevalence of respiratory disease and the overall agreement between the 2 scoring systems. The overall agreement between the VAS and WCHSC was 89.6%. The second part of the study assessed interobserver reliability between 2 experienced observers and between an experienced observer and veterinary students. The interobserver reliability was calculated by intraclass correlation coefficient and was 0.58 between experienced observers and was 0.34 between an experienced observer and veterinary students indicating a moderate to poor reliability between the observers. It was possible to use VAS as an alternative clinical scoring method, which primarily focuses on the general condition of the individual calf rather than specific categories of clinical signs. Our study set up lacked a comparison to other diagnostic tools i.e., thoracic ultrasound to confirm the findings which should be considered in future studies when exploring VAS as a screening tool for detection of respiratory disease in dairy calves.

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.

Thoracic electrical impedance tomography identifies heterogeneity in lungs associated with respiratory disease in cattle. A pilot study

Respiratory disease in cattle is a significant global concern, yet current diagnostic methods are limited, and there is a lack of crush-side tests for detecting active disease. To address this gap, we propose utilizing electrical impedance tomography (EIT), a non-invasive imaging technique that provides real-time visualization of lung ventilation dynamics. The study included adult cattle from farms in Western Australia. The cattle were restrained in a crush. A standardized respiratory scoring system, which combined visual, auscultation, and clinical scores, was conducted by two non-conferring clinicians for each animal. The scores were blinded and averaged. During assessment, an EIT electrode belt was placed around the thorax. EIT recordings of ten suitable breaths were taken for analysis before the cattle were released back to the herd. Based on the combined examination scoring, the cattle were categorized as having healthy or diseased lungs. To allow visual interpretation of each breath and enable the creation of the quartile ventilation ratio (VQR), Flow/Tidal Impedance Variation curves (F/TIV) were generated for each breath. The analysis focused on two EIT variables: The novel VQR over time during inhalation and exhalation and global expiratory impedance (TIVEXP) adjusted by breath length. A mixed effects model was used to compare these variables between healthy and diseased cattle. Ten adult cattle of mixed ages were used in the current analysis. Five cattle were scored as healthy and five as diseased. There was a significant difference in the examination scores between the healthy and diseased group (P = 0.03). A significant difference in VQR during inhalation (P = 0.03) was observed between the healthy and diseased groups. No difference was seen in VQR over time during exhalation (P = 0.3). The TIVEXP was not different between groups (P = 0.36). In this study, EIT was able to detect differences in inhalation mechanics when comparing healthy and diseased cattle as defined via clinical examination, highlighting the clinical utility of EIT.

Agreement among deep nasopharyngeal sampling culture results for 3 different swab types in preweaning dairy calves

Accurate isolation and identification of pathogens for an animal with bovine respiratory disease are of critical importance to direct appropriate decision-making related to the treatment of individual animals, as well as control and prevention options in a herd setting. The objective of this study was to compare nasopharyngeal sampling approaches to evaluate accuracy and agreement for the recovery of Mannheimia haemolytica (MH) and Pasteurella multocida (PM) from deep nasopharyngeal swabs (DNS) using 3 different swabs. Deep nasopharyngeal samples were collected from 45 dairy calves using 3 swabs: (1) double-guarded culture swab (DGS); (2) single-guarded culture swab (SGS); and (3) unguarded culture swab (UGS). To evaluate the degree of agreement between DGS, SGS, and UGS, culture results were compared for each calf sampled by using a kappa agreement test. Overall, findings from our study support that when using either SGS or DGS for DNS sampling of preweaning calves, a high agreement for recovery of PM is observed. A low recovery of MH was observed in the study, limiting the conclusion comparing the 3 DNS methods. Use of UGS is considered a potential alternative; however, a higher percentage of polymicrobial growth was found with UGS samples.

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.

Evaluation of First Treatment Timing, Fatal Disease Onset, and Days from First Treatment to Death Associated with Bovine Respiratory Disease in Feedlot Cattle

Bovine respiratory disease (BRD) is a frequent beef cattle syndrome. Improved understanding of the timing of BRD events, including subsequent deleterious outcomes, promotes efficient resource allocation. This study’s objective was to determine differences in timing distributions of initial BRD treatments (Tx1), days to death after initial treatment (DTD), and days after arrival to fatal disease onset (FDO). Individual animal records for the first BRD treatment (n = 301,721) or BRD mortality (n = 19,332) were received from 25 feed yards. A subset of data (318–363 kg; steers/heifers) was created and Wasserstein distances were used to compare temporal distributions of Tx1, FDO, and DTD across genders (steers/heifers) and the quarter of arrival. Disease frequency varied by quarter with the greatest Wasserstein distances observed between Q2 and Q3 and between Q2 and Q4. Cattle arriving in Q3 and Q4 had earlier Tx1 events than in Q2. Evaluating FDO and DTD revealed the greatest Wasserstein distance between cattle arriving in Q2 and Q4, with cattle arriving in Q2 having later events. Distributions of FDO varied by gender and quarter and typically had wide distributions with the largest 25–75% quartiles ranging from 20 to 80 days (heifers arriving in Q2). The DTD had right-skewed distributions with 25% of cases occurring by days 3–4 post-treatment. Results illustrate temporal disease and outcome patterns are largely right-skewed and may not be well represented by simple arithmetic means. Knowledge of typical temporal patterns allows cattle health managers to focus disease control efforts on the correct groups of cattle at the appropriate time.

Comparison of calf morbidity, mortality, and future performance across categories of passive immunity: A retrospective cohort study in a dairy herd

Four categories of transfer of passive immunity (TPI) were recently proposed in response to the widespread high preweaning morbidity and mortality risks in calves with adequate TPI when a dichotomous classification was used. Hitherto, however, the risks of preweaning morbidity and mortality and future performance among these TPI categories have not been compared. Thus, the objective of this retrospective cohort study was to compare dairy calf morbidity, mortality, growth until weaning, and reproductive efficiency until first calving among the categories of poor (<5.1 g/dL total protein), fair (5.1-5.7 g/dL), good (5.8-6.1 g/dL), and excellent (>6.2 g/dL) TPI. For this, the records from 4,336 dairy calves (2,272 female, 2,064 male) born January 2014 to April 2017 on a commercial dairy farm in Michigan were analyzed. These calves had been randomly selected for weekly serum total protein determination on calves 2 to 7 d old. Data from both sexes were used to evaluate preweaning health and mortality, whereas only the female's data were used to investigate average daily gain (ADG), reproductive performance, and first-lactation milk yield. For each calf, data regarding disease status, growth, and reproductive parameters were obtained from the farm's software database. Associations of TPI categories with disease events (diarrhea or pneumonia), reproduction indices (age at first insemination, successful insemination, and calving, and number of inseminations), first-lactation milk yield and ADG at weaning were evaluated by survival analysis and mixed models. Compared with calves with excellent TPI, calves in the inferior TPI categories showed increased risk of diarrhea: poor [hazard ratio (HR) = 1.49; 95% CI: 1.22-1.82], fair (HR = 1.32; 95% CI: 1.16-1.51), good (HR = 1.14; 95% CI: 1.02-1.29). However, the risk of pneumonia differed only between the calves in the poor and excellent TPI groups (HR = 1.39; 95% CI: 1.05-1.84). The preweaning mortality risk was also higher in calves with poor TPI (HR = 4.29; 95% CI: 1.98-9.27) compared with excellent TPI. However, mortality risks were not statistically different between calves with fair or good TPI and those with excellent TPI. Similarly, calves with poor TPI had a 64, 55, and 24% lower risk of reaching first insemination, successful insemination, or first calving, respectively. However, there were no differences in ADG, number of inseminations, or first-lactation 305-d mature equivalent milk production across TPI groups. Our results confirm the positive effects of optimal TPI in calf preweaning health and postweaning reproductive efficiency. The 4 proposed categories of TPI can assist in decreasing the incidence of diseases that occur in the first weeks of life (i.e., diarrhea), but their effect on other diseases or future performance might be more limited. Although conducted in one herd, this study can be used to illustrate the effect of TPI on future calf performance.

Veterinarians' perspectives of pain, treatment, and diagnostics for bovine respiratory disease in preweaned dairy calves

Background

Bovine Respiratory Disease (BRD) is a leading cause of morbidity and mortality in preweaned dairy calves. Early detection and therefore treatment are essential to minimize animal welfare concerns, particularly given that recent research also demonstrates that BRD is painful. Veterinarians are essential to ensuring calves with BRD receive appropriate treatment, but little to no research exists regarding veterinarians' perspectives about BRD detection and treatment in dairy calves. This is a critical step to determine education and outreach needs that can target BRD treatment to improve calf welfare. Thus, the objectives of the current study were to describe US veterinarians' current detection methods and treatment practices for BRD in preweaned dairy calves, understand veterinarians' rationale for treatment decisions, and identify gaps in knowledge regarding treatment and management of calf BRD.

Methods

An online survey was sent to two veterinarian-focused list-serves and newsletter. Final responses (n = 47) were analyzed using qualitative and quantitative analyses.

Results

On-farm necropsy was the diagnostic tool most considered "extremely important" (26, 55.3%). All veterinarians indicated that BRD was at least mildly painful. However, only 53% of veterinarians (n = 25) assess pain in preweaned calves with BRD in order to make treatment decisions. Furthermore, of the veterinarians that assessed pain, 40% (n = 10) reported that their knowledge of pain assessment and treatment was adequate, but most (n = 24) considered a calf's pain-level at least "moderately important" to make BRD treatment decisions. The most important ancillary therapy for antimicrobials were NSAIDs (21, 44.7%). The ancillary therapy most often considered "extremely important" for treating BRD was NSAIDs. Qualitative analysis identified the following as factors that influenced veterinarians' willingness to provide analgesia: the farm's willingness to administer drugs, clinical signs, perceived severity of pain, the need for anti-inflammatories, and the presence of fever and comorbidities.

Discussion

This study included a small sample size and an extremely low response rate; results should therefore be interpreted with caution. Despite this limitation, important gaps in knowledge were identified, including pain assessment and consideration when making treatment decisions, and diagnostic tools. Addressing these needs in future research and outreach efforts could help ensure appropriate and timely treatment of calf BRD, including pain mitigation.

Clinical Scoring Systems in the Newborn Calf: An Overview

Simple Summary

Clinical scores are gaining increasing popularity in veterinary medicine thanks to their multiple advantages, which include quickness, ease, and convenience of use. This review discusses the applications of some already-known clinical scores in newborn calf management at birth and during the first weeks of age. Clinical scores are employed to assess newborn calf viability and to diagnose and monitor neonatal calf diarrhea and respiratory diseases, helping the clinician promptly recognize calves needing medical assistance. This review discusses limitations pertaining to their use and encourages efforts towards a greater consistency in definition and validation.

Abstract

A scoring system is an instrument that enables the scorers, including farmers, technicians, and veterinarians, to adopt a systematic approach for diagnosis or monitoring, as it decreases bias and confounding and increases objectivity. Practically, it is a number assigned to a patient that correlates with a probability that a diagnosis can be confirmed or that a specific outcome will follow. This article examines the clinical scores designed or adapted to bovine medicine that aim to assess newborn calf viability and to diagnose and monitor neonatal calf diarrhea and respiratory diseases, helping the clinician promptly recognize calves needing medical assistance. Despite the large number of clinical scores described in the literature, these are still barely used in farm animal practice; possibly, the complexity of the scores and missing recommendations for intervention are reasons for their lack of popularity as well as the crosswise lack of consistency among scores designed for the same purpose. Further research is needed in this regard to increase scores validation and encourage their application in bovine calf neonatology.

Technological Tools for the Early Detection of Bovine Respiratory Disease in Farms

Simple Summary

The inclusion of remote automatic systems that use continuous learning technology are of great interest in precision livestock cattle farming, since the average size of farms is increasing while time for individual observation is decreasing. Bovine respiratory disease is a main concern in both fattening and heifer rearing farms due to its impact on antibiotic use, loss of performance, mortality, and animal welfare. Much scientific literature has been published regarding technologies for continuous learning and monitoring of cattle’s behavior and accurate correlation with health status, including early detection of bovine respiratory disease. This review summarizes the up-to-date technologies for early diagnosis of bovine respiratory disease and discusses their advantages and disadvantages under practical conditions.

Abstract

Classically, the diagnosis of respiratory disease in cattle has been based on observation of clinical signs and the behavior of the animals, but this technique can be subjective, time-consuming and labor intensive. It also requires proper training of staff and lacks sensitivity (Se) and specificity (Sp). Furthermore, respiratory disease is diagnosed too late, when the animal already has severe lesions. A total of 104 papers were included in this review. The use of new advanced technologies that allow early diagnosis of diseases using real-time data analysis may be the future of cattle farms. These technologies allow continuous, remote, and objective assessment of animal behavior and diagnosis of bovine respiratory disease with improved Se and Sp. The most commonly used behavioral variables are eating behavior and physical activity. Diagnosis of bovine respiratory disease may experience a significant change with the help of big data combined with machine learning, and may even integrate metabolomics as disease markers. Advanced technologies should not be a substitute for practitioners, farmers or technicians, but could help achieve a much more accurate and earlier diagnosis of respiratory disease and, therefore, reduce the use of antibiotics, increase animal welfare and sustainability of livestock farms. This review aims to familiarize practitioners and farmers with the advantages and disadvantages of the advanced technological diagnostic tools for bovine respiratory disease and introduce recent clinical applications.

Respiratory pathogens in veal calves: Inventory of circulating pathogens

In the veal industry in The Netherlands, each year around 1.2 million "white" veal calves are produced on around 1100 farms. Bovine respiratory disease (BRD) causes serious health issues in these calves, also resulting in high usage of antimicrobials. To reduce antimicrobial usage, a more targeted treatment regime is needed, for which it is necessary to identify the causative agent. This study aimed at determining associations between pathogens and clinical disease, between prevalence of pathogens and BRD outbreaks, and BRD and performance. A cohort study was conducted involving ten veal farms, in which calf respiratory health was evaluated for the first 12 weeks. Whenever there was an outbreak of BRD, as determined by the farm veterinary surgeon, samples were taken from diseased and control calves through broncho-alveolar lavage. From these samples a broad spectrum of micro-organisms were isolated. Performance data were also collected. A total of 23 outbreaks happened during the 12 week study period, mostly in the first six weeks. BRD associated pathogens found were: BHV1, BPI3V, BRSV, BVDV, Pasteurella multocida, Mannheimia haemolytica, Trueperella pyogenes, Histophilus somni, Mycoplasma bovis, Mycoplasma bovirhinis and Mycoplasma dispar. For most BRD associated pathogens, there was no clear association between presence or prevalence of the micro-organisms and clinical issues. Only T. pyogenes (7.4% in healthy, 14.6% in diseased calves, p 0.013), M. bovis (37.6% and 63.2% respectively, p 0.001) and BVDV (9.9% and 16.9% respectively, p 0.03) were found more often in diseased animals. BPI3V was found in a few early outbreaks, which might suggest involvement in early outbreaks. It appears to be difficult to associate specific pathogens to outbreaks at the species level. BRD is the major reason for treatment with antimicrobials. More specific knowledge about the association between pathogens and health/disease could help to reduce antimicrobial use.

Assessment of Rapid MinION Nanopore DNA Virus Meta-Genomics Using Calves Experimentally Infected with Bovine Herpes Virus-1

Bovine respiratory disease (BRD), which is the leading cause of morbidity and mortality in cattle, is caused by numerous known and unknown viruses and is responsible for the widespread use of broad-spectrum antibiotics despite the use of polymicrobial BRD vaccines. Viral metagenomics sequencing on the portable, inexpensive Oxford Nanopore Technologies MinION sequencer and sequence analysis with its associated user-friendly point-and-click Epi2ME cloud-based pathogen identification software has the potential for point-of-care/same-day/sample-to-result metagenomic sequence diagnostics of known and unknown BRD pathogens to inform a rapid response and vaccine design. We assessed this potential using in vitro viral cell cultures and nasal swabs taken from calves that were experimentally challenged with a single known BRD-associated DNA virus, namely, bovine herpes virus 1. Extensive optimisation of the standard Oxford Nanopore library preparation protocols, particularly a reduction in the PCR bias of library amplification, was required before BoHV-1 could be identified as the main virus in the in vitro cell cultures and nasal swab samples within approximately 7 h from sample to result. In addition, we observed incorrect assignment of the bovine sequence to bacterial and viral taxa due to the presence of poor-quality bacterial and viral genome assemblies in the RefSeq database used by the EpiME Fastq WIMP pathogen identification software.

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.

Diagnostic accuracy of Wisconsin and California scoring systems to detect bovine respiratory disease in preweaning dairy calves under subtropical environmental conditions

Bovine respiratory disease (BRD) is a multifactorial disease which causes short- and long-term negative effects. Early detection is crucial for a prompt response to therapy, as well as to decrease mortality risk. Clinical scoring systems have been developed mostly in North America for screening calves at risk or suspected of having BRD, and these tools have also been applied in subtropical and tropical countries. However, it has been unknown whether these scoring systems had the same accuracy in tropical environmental conditions. Therefore, this study evaluated the accuracy of 4 different field techniques, as well as serum haptoglobin (HAP), to diagnose BRD in Holstein dairy calves in subtropical conditions. The tests used to diagnose BRD were thoracic ultrasound (TUS; positive if consolidation depth ≥1 cm), thoracic auscultation (AUSC; positive if crackles, wheezes, or silent areas were present), Wisconsin score (WISC; ≥2 categories with scores of ≥2), and California score (CALIF; positive if total score ≥5). Also, HAP was measured and classified as positive if ≥15 mg/dL. Heifers between 30 d of age and weaning (n = 482), residing on 17 commercial dairies in São Paulo state, were enrolled in this study. Bayesian latent class models were used with informative priors to evaluate the accuracy of TUS, AUSC, and HAP, and noninformative priors for the accuracy of WISC and CALIF. The percentage of calves positive for each test on each farm ranged from 0 to 56% for WISC, 11-51% for CALIF, 0-72% for TUS, 0-32% for AUSC, and 0-100% for HAP. The sensitivity (Se; 95% credible interval) and specificity (Sp) for WISC were 77.9% (64.8-90.2) and 81.9% (76.3-88.2). For CALIF, the Se was 67.1% (53.6-80.1) and Sp 79.1% (73.9-84.6). For TUS Se was 59.8% (46.5-73.1) and Sp was 84.8% (80.0-89.5), and for AUSC, Se was 58.8% (41.3-79.8) and Sp was 98.6% (95.7-99.9). The Se and Sp of HAP was 67.6% (55.3-78.8) and 46.7% (41.4-52.2), respectively. The performance of the scoring systems was similar to, or better than, the performance found in North American studies, despite the fact that calves were in a tropical environment.

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.

Ultrasonography and digital radiography findings in sheep with clinical disease associated with small ruminant lentivirus infection

Digital radiography and ultrasonographic images were used in this case series to evaluate 4 ewes from a single flock for chronic weight loss and ill-thrift. On examination, all displayed tachypnea, dyspnea, coughing, and normothermia with abnormal thoracic auscultations. Three of the 4 animals were diagnosed with chronic respiratory disease associated with Maedi-visna (MV) infection confirmed via serologic testing. Diagnostic thoracic imaging identified characteristics consistent with pathological lesions associated with interstitial pneumonia in the 3 MV affected animals; these findings were absent in the animal that tested negative for MV. Key clinical message: Diagnostic imaging may be useful to clinicians looking to obtain further visualization of lung pathologies and as a reliable means of detecting thoracic lesions indicative of interstitial pneumonia on-farm. These results can be used to aid the practitioner in determining appropriate further diagnostic testing and treatment strategies while awaiting confirmatory test results for diagnosis of MV.