The data present the prevalence of leptospirosis in cattle on the territory of Ukraine over the last eight years (2005-2012) and the dynamics of changes of the etiological structure of the agent. Territorial diffusion of leptospirosis outbreak has also been studied. The outbreaks? density map was completed based on these data, depending on the number of cases in cattle. All areas of the country were divided into risk of infection four zones: low, medium, high and extra high risk.

The article presents data on histopathological studies of the kidneys of cows, which either recovered or died from leptospirosis. Fragments of seven kidneys from slaughtered cows, positive for Leptospira antibodies in the microscopic agglutination test (MAT) (titres of 50 and higher) were used in the study. The MAT was conducted with eight serological groups of Leptospira: Canicola, Grippotyphosa, Hebdomadis, Icterohaemorrhagiae, Pomona, Sejroe, Tarassovi, and Australis. Microscopic changes in all morphological structures of the kidneys were presented. Micromorphological criteria, which can be used for post-mortem diagnosis of leptospirosis were established. They included: serous glomerulonephritis with granular dystrophy of podocytes, necrosis and collapse of the inner layer of Bowman's capsule, partial destruction of capsule and vascular glomeruli, granular and vacuolar degeneration and destruction of tubular epithelial cells, foci of interstitial oedema, and infiltrations predominantly with monocytes and isolated neutrophils. Microscopic changes in the kidneys suggest that the cows died from leptospirosis as a result of toxic shock syndrome.