Microbiologic Characterization of Equine Mastitis

Mastitis occurrence in mares is low if compared to other livestock species. The microorganisms often isolated and detected in milk and mammary gland secretions of mares are Streptococcus beta-haemolytica, Staphylococcus spp., Pseudomonas aeruginosa, Actinobacillus spp., and enterobacter. The present experiment was designed to evaluate the main microorganisms present in the milk of healthy mares and having a mammary infection. One hundred and ten mammary glands from 55 lactating mares were analyzed, ranging from 15 to 150 d post-partum. The mastitis diagnostic was performed through analysis of the milk via the screened test of the mug with dark background (Tamis), mammary gland inflammation and/or systemic signs. The subclinical mammary gland infection was characterized via the California Mastitis Test (CMT). From the 55 lactating mares, 2 (3.64%) had clinical mastitis. Following the CMT, the mares presented: 13 (23.60 %), 7 (12.72%), and 12 (21.88%) scores from 1+, 2+, and 3+, respectively. From the 110 mamary glands were analysed, in 47 (85.45%) of these samples strains of microorganisms were isolated. In summary, results from our experiment suggest a low occurrence of clinical mastitis in lactating mares.