Global climate change in recent decades has led to an increase in the activity and expansion of the range of many diseases. One of them is canine babesiosis. Therefore, it is becoming increasingly important to monitor the functional state of the organism in sick dogs and timely detection of kidney, liver, spleen, cardiovascular system, anaemia, and other disorders that complicate the course of babesiosis. The research aims to determine the peculiarities of metabolic and functional changes in dogs with different intensities of babesiosis infection. During the laboratory diagnostics, general and special research methods were used: light microscopy, centrifugation, spectrophotometry, and mathematical statistics. Based on the results of comprehensive microscopic, morphological, and biochemical studies of blood in dogs with different intensities of babesiosis infection, the most characteristic functional and metabolic changes in their body were identified. Thus, at different intensities of babesiosis infection in diseased animals, the features of the haematological profile are leukocytopenia against the background of eosinopenia (at a mild degree of infection) and lymphocytopenia with a simultaneous compensatory increase in the number of monocytes and neutrophils, as well as erythrocytopenia, hypochromemia, thrombocytopenia with a decrease in thrombocrit and haematocrit. In addition, these patients developed hyperfermentemia of aspartate and alanine aminotransferases, alkaline phosphatase, and γ-glutamyl transpeptidase, indicating structural and functional changes, primarily in the myocardium, liver, skeletal muscle, brain and kidneys due to their toxic damage by babesia waste products. At the same time, hypoproteinaemia, hypoalbuminemia and hyperazotemia were observed in the affected animals, indicating an increase in the intensity of catabolic processes in functional cells of organs and tissues, especially the liver. The most pronounced changes in the studied parameters were observed at high intensity of babesiosis infection. The established regularities allow the use of these haematological parameters as markers of functional and metabolic changes in the body of dogs at different intensities of babesiosis infection