This work aims to study the elemental status of dog hair in ontogeny. The studies were conducted on animals 2–4 and 8–10 years of age. Under observation were 39 dogs of the following breeds: Rottweilers, Dalmatians, Black Terriers, Golden Retrievers, Labradors and Dobermans. The animals were born and kept in Novosibirsk, Tomsk, Yalta and Moscow. The dogs were kept in apartments with obligatory morning and evening exercise. Wool was sheared from the withers to determine the concentration of bioelements. The bioelemental composition of wool was determined on an Elan 9000 quadrupole mass spectrometer and an Optima 2000DV atomic emission spectrometer by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. The research was carried out during the summer period. The diet of dogs consisted of dry industrial feed, balanced in terms of essential nutrients, vitamins, and macro- and microelements. In the research process, specific microelementoses were found in dogs of different ages. The obtained results showed that dogs of 2-4 years of age exceed 8-10-year-old animals in the concentration of aluminium in wool by 81.3% (P<0.01), chromium - by 67.1 (P<0.001), copper - by 27.4 (P<0.05), iron - by 81.7 (P<0.05), mercury - by 70.5 (P<0.05), iodine - by 68.3 (P< 0.05), potassium – by 57.5 (P<0.01), lithium – by 65.7 (P<0.05), lead – by 84.5 (P<0.05), vanadium – by 56.6 (P<0.05) and zinc by 27.9% (P<0.01). At the same time, in the group of 2-4-year-old animals, the iodine level exceeded the limit of reference values by 35.5%. On the other hand, in dogs of 8–10 years, chromium, iron, iodine, manganese, and silicon indicators have lagged behind the lower limit of the reference values by 45.0, respectively; 89.9, 86.0, 91.0 and 89.7%.
