SUMMARY
Leptospirosis and babesiosis in dogs may be associated. These diseases often have similar symptoms and mask each other, or are asymptomatic, which complicates the diagnosis, significantly worsens the prognosis and reduces the survival of sick animals. Monitoring of the associated course of leptospirosis and babesiosis in dogs makes it possible to study the frequency of this parasitocenosis in dogs and the peculiarities of its course, which is the basis for improving the diagnosis and treatment of sick animals.The aim of the research. Monitor the associated course of leptospirosis and babesiosis in dogs.Methods. The research was conducted in the private veterinary clinic “Vetservice” in Sumy and in the serology department of the Sumy Regional State Laboratory of the Civil Service of Ukraine for Food Safety and Consumer Protection. Blood samples were taken from dogs came for treatment to the “Vetservice” clinic. The diagnosis of babesiosis was established directly in the clinic by the results of erythrocyte microscopy in thin smears of peripheral blood of sick dogs stained by Giemsa. The diagnosis of leptospirosis was established in the serology department of the Sumy Regional State Laboratory based on the results of a study of the serum of sick dogs in the microagglutination reaction. The subjects of the study were clinically ill and suspected dogs with the associated course of leptospirosis and babesiosis, as well as blood samples from these animals. Babesium trophozoites were detected in erythrocytes under an immersion microscope, a magnification of ocular 10 x 90, and the presence of antibodies to leptospira was detected by the presence of agglutination of leptospira in microagglutination reaction.Results. In the study of the incidence of dogs associated with leptospirosis and babesiosis during 2014–2019, according to the clinic “Vetservice” found that the number of reported cases of associated leptospirosis and babesiosis annually varies from 9 to 28 cases. This parasitocenosis is registered all year round with peaks in spring and autumn, moderately in summer and rarely in winter. Purebred animals get sick several times more often than non pedigree ones. During the period from 2016 to 2019, the number of diseases in females and males was approximately the same. During the period from 2014 to 2015, males were more often ill.Conclusions. The prevalence of the associated course of leptospirosis and babesiosis in dogs of the Sumy region of Ukraine was determined with the determination of seasonal, breed and sexual dynamics of this parasitocenosis