Introduction:

Mastitis is defined as the inflammation of the mammary gland causing great economic losses in dairy herds, which merits investigation.

Objective:

To determine the incidence rate of clinical mastitis IRCM, associated etiology, and antibiotic sensitivity of pathogens isolated from cases of mastitis in dairy cattle.

Materials and methods:

37 herds were followed during 12 months for clinical mastitis (CM) diagnosis. Milk samples from CM cases were bacteriologically cultured, which underwent, along with isolates from subclinical mastitis cases from a previous study, antibiotic susceptibility testing. For data analysis, standard descriptive statistics were used.

Results:

The IRCM was 13.8 cases per 100 cows-year at risk. A total of 188 pathogens of CM cases were isolated, among which Streptococcus agalactiae, Streptococcus pyogenes, and Corynebacterium spp. were the most frequent, with 29.8%, 11.7%, and 5.9%, respectively. A high susceptibility of contagious bacteria was found for cloxacillin and cefoperazone.

Conclusions:

The present study found an IRCM of 13.8 cases per 100 cows-year at risk. The most prevalent pathogens identified in cases of CM were contagious. A high sensitivity of contagious bacteria was found for most β-lactam antibiotics.

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