Abstract
<jats:p>Bovine mastitis remains one of the most significant challenges in dairy cattle production at present, both in several CIS countries and, in particular, in Kazakhstan. Despite the increased attention of veterinary specialists to general preventive measures and the development of specific therapeutic agents for mastitis treatment, the issue continues to be highly relevant. As part of this study, an epizootiological survey of lactating cattle was conducted to assess the prevalence of mastitis on dairy farms located in the East Kazakhstan, Karaganda, and Turkestan regions. Mastitis cases were identified on all six examined farms, with morbidity rates ranging from 5.2% in the Turkestan region to 26.4% in the East Kazakhstan region. Clinical examination and laboratory analyses revealed that 97.6% of affected cows exhibited serous and catarrhal forms of mastitis, while 2.4% were diagnosed with the hemorrhagic form. In 70.2% of cases, the posterior quarters of the udder were affected, whereas the anterior quarters were involved in 29.8% of animals. Additionally, lesions were observed in a single udder quarter in 12.9% of cases and in two quarters in 7.3% of cases. Microbiological analysis of the collected milk samples demonstrated that monocultures of microorganisms were detected only in isolated cases in samples obtained from mastitis-affected animals. In most samples, microbial associations were identified, predominantly represented by bacteria of the genera Streptococcus, Staphylococcus, and Escherichia coli. Identification of staphylococcal isolates from milk obtained from dairy cows in the East Kazakhstan and Karaganda regions confirmed the presence of Staphylococcus aureus, which exhibited pathogenicity in laboratory white mice. Antimicrobial susceptibility and resistance testing showed that this strain was sensitive to azithromycin, ampicillin, and gentamicin, as well as to intramammary combination antimicrobial preparations such as “Tilomast,” “Mastigard,” “Mastite-Forte,” and “Mastimax,” while demonstrating low sensitivity to streptomycin and erythromycin.</jats:p>