The research aimed to identify latent mastitis in cows on farms in the Republic of Armenia by counting somatic cells in milk using the California method. Among the 170 animals examined, 60 had latent mastitis, which comprised 35.2 % of the population. The highest incidence was observed in the Vayoc Dzor region (50 %), while the lowest was found in the Sunik region (25 %). It was found that 40 animals (23.5 %) showed a pronounced reaction to mastitis, and the concentration of somatic cells in milk was 300-500 thousand/sm3. 20 animals demonstrated a positive reaction to the test (11.7 %), and the number of somatic cells in milk exceeded 500 thousand/sm3. A microbiological study of milk from animals with subclinical mastitis was conducted to determine the species composition of pathogenic microflora. The study indicated that the milk was highly contaminated with staphylococcus, streptococcus, corynebacterial, E. coli, mycoplasma, candida, etc. A rise in leukocytes was observed in the blood of sick animals, as well as increases in band neutrophils, eosinophils, monocytes, lymphocytes, and ESRs. All this indicates, there is an inflammatory process present in the body and the immune system is mobilizing to fight pathology.

Latent mastitis harms the health of animals, their milk production, and the quality of milk. In cows affected by this disease sharp changes in hematological parameters, and biochemical parameters of blood and milk, which is the focus of our research. This work studies the morphological and biochemical parameters of blood and the biochemical parameters of milk in dairy cows affected by latent mastitis. The research was performed in several farms and farm households of Kotayk and Ararat regions, as well as in the ANAU Research Center of Veterinary Medicine and Veterinary Sanitary laboratories. The research outcomes prove that latent mastitis significantly impacts the composition of blood and milk components. Data obtained during the research enables a better understanding of the causes of mastitis as well as the necessity of using informative diagnostic methods in farm veterinarians’ practices.