Nowadays special attention must be paid to pathology associated with the violation of the change of milk teeth to permanent of dogs of dwarf breeds. This fact is confirmed by the results of a statistical analysis of appeals from dog owners to specialized dental care at the “Veterinary Hospital”: 33 % of the animals were diagnosed with “false polyodontics” a general increase in the number of teeth due to non-temporal loss. In the literature, it is noted that the hormones of the thyroid and parathyroid glands, sex hormones regulate the exchange of calcium and phosphorus in the blood, thereby affecting the speed of tooth changes and the degree of bone mineralization. As a result of the research, the authors determined the features of hormonal and mineral homeostasis of the body during the period of teeth change in dogs of dwarf breeds at the age of 6 months in the blood serum, characterized by the thyroid gland profile, sex hormones – at the lower reference values, increased phosphorus and calcium levels.