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

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

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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

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

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

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

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

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

BACKGROUND

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

OBJECTIVES

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

ANIMALS

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

METHODS

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

RESULTS

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

CONCLUSIONS AND CLINICAL IMPORTANCE

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

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.

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.