CLINICAL DIAGNOSIS AND TREATMENT OUTCOMES OF INFECTIOUS DISEASES IN DAIRY CATTLE

Abstract

The global dairy industry suffers significant economic consequences due to bovine mastitis and other infectious diseases further aggravated by the growing antimicrobial resistance and the broad-spectrum use of antibiotics in an empirical manner. The study compared the effects of rapid diagnostic-guided therapy with treatment outcome, antimicrobial use, resistance development and economic analysis with empirical therapy in dairy cattle with clinical mastitis. The systematic review and meta-analysis of 48 studies were coupled with a prospective field validation study of 289 cows in five commercial dairy farms with parallel milk testing on nine diagnostic platforms such as conventional culture, MALDI-TOF MS, real-time PCR, LAMP, chromogenic point-of-care tests, lateral flow immunoassays, and next-generation sequencing. Measurements of diagnostic accuracy were computed and cows were randomized to empirical and diagnostic guided treatment groups with 90-day follow-up on clinical cure, bacteriological cure, relapse, prevalence of resistance and cost analysis. MALDI-TOF MS had the highest odds ratio of diagnosis of 312.7, then it was on-farm PCR of 198.5. Diagnostic-guided therapy greatly enhanced bacteriological cure (59.2 to 78.9, number needed to treat 5.1), minimized treatment failure (53.4 percent), and shortened median cure time (2.6 to 5.0 days) in pathogens. There was a 50.0 percent reduction of antimicrobial dosages and four times less resistance increase in 90 days in the diagnostic-guided arm. Direct costs per cow dropped by 62.43 (36.1 percent drop). Diagnostic guidance was reported as the best predictor of treatment success (adjusted odds ratio 3.27) with multivariate regression. On-farm PCR devices showed near-perfect consistency with reference methodologies (kappa 0.834 -0.902). These results confirm that the diagnostic-based therapy is significantly superior to empirical therapy in all clinical outcomes of interest, which is why the point-of-care and molecular diagnostics should be implemented into the everyday dairy practice to improve antimicrobial stewardship, maintain current drug efficacy, and become more economically sustainable.