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.

Performance of bovine genital campylobacteriosis diagnostic tests in bulls from Uruguay: a Bayesian latent class model approach.

The sensitivity (Se) and specificity (Sp) of three diagnostic tests for the detection of Campylobacter fetus venerealis (Cfv) using field samples were estimated using a Bayesian latent class model (BLCM), accounting for the absence of a gold standard. The tests included in this study were direct immunofluorescence antibody test (IFAT), polymerase chain reaction (PCR), and real-time PCR (RT-PCR). Twelve farms from two different populations were selected and bull prepuce samples were collected. The IFAT was performed according to the OIE Manual. The conventional PCR was performed as multiplex, targeting the gene nahE for C. fetus species identification and insertion element ISCfe1 for Cfv identification. The RT-PCR was performed as uniplex: one targeting the gene nahE for C. fetus and the other targeting the insertion ISCfe1 (ISC2) for Cfv. Results from the BLCM showed a median Se of 11.7% (Bayesian credibility interval (BCI): 1.93-29.79%), 53.7% (BCI: 23.1-95.0%), and 36.1% (BCI: 14.5-71.7%) for IFAT, PCR, and RT-PCR respectively. The Sp were 94.5% (BCI: 90.1-97.9%), 97.0% (BCI: 92.9-99.3%), and 98.4% (BCI: 95.3-99.7%) for IFAT, PCR, and RT-PCR respectively. The correlation between PCR and RT-PCR was positive and low in samples from both sampled population (0.63% vs 8.47%). These results suggest that diagnostic sensitivity of the studied tests is lower using field samples than using pure Cfv strains.