Bovine Mastitis and Detection of Staphylococcus aureus Among Dairy Cows in Dessie Town, Northeast Ethiopia: Prevalence and Associated Risk Factors

Abstract

Background Bovine mastitis is a major economic challenge to dairy production globally. Despite its impact, there is limited information on the disease and its associated risk factors in the dairy sector of Dessie Town, Northeast Ethiopia. This study aimed to determine the prevalence of bovine mastitis, identify risk factors, and isolate Staphylococcus aureus from mastitic milk in the study area. Methods A cross‐sectional study was conducted on 304 lactating dairy cows across smallholder farms and semi‐intensive farms. Clinical examination and the California mastitis test (CMT) were used to detect clinical and subclinical mastitis, respectively. Risk factors were assessed via structured questionnaires and analyzed through univariate and multivariable logistic regression. Out of 374 mastitis‐positive quarters identified, 52 were blind teats; consequently, a bacteriological analysis was performed on the remaining 322 viable milk samples for the exclusive isolation of Staphylococcus aureus via standard microbiological techniques. Results The cow‐level prevalence of mastitis was 61.18%, with the prevalence of subclinical cases (48.68%) far exceeding that of clinical cases (12.5%). At the quarter level, 30.75% of the teats were affected. The right rear quarter showed the highest prevalence (34.21%), whereas the left front quarter was least affected (27.63%). Multivariable logistic regression revealed that crossbreed (AOR = 10.15; 95% CI: 2.52–40.94; p = 0.001), many parity (AOR = 20.05; 95% CI: 3.32–147.24; p = 0.001), poor milking hygiene (AOR = 5.64; 95% CI: 1.35–23.52; p = 0.017), and long and wide teat end morphology (AOR = 9.03; 95% CI: 2.15–37.98; p = 0.003) were significant predictors of mastitis occurrence. Staphylococcus aureus was isolated from 35.71% of mastitis‐positive milk samples, including 37.36% from clinical samples and 35.06% from subclinical samples. Conclusion This study revealed a high burden of both clinical and subclinical mastitis in dairy farms around Dessie Town, with S. aureus being a leading pathogen. The strong association between mastitis and risk factors such as hygiene and teat anatomy highlights the need for integrated control measures, farmer training, and routine screening to improve udder health and milk quality.