SUMMARY
Intoxication of canaries with canthaxanthin has been recorded more and more often since the late 1990s. This problem is related to active use of this substance for changing or increasing the colouration of this species of bird. For determining morphological changes during canthaxanthin toxicosis, we formed one control and three experimental groups of domestic canaries, which were given canthaxanthin in different doses. The material for microscopic surveys was isolated from the digestive organs of the examined birds; from this material, histological sections were prepared and stained with hematoxylin and eosin. According to the results of microscopic analysis, we determined that the intoxication of the organism of canaries with canthaxanthin causes a certain complex of changes at the tissue level. We found that canthaxanthin intoxication leads to chronic pathological processes in the digestive organs, both the digestive canal and digestive glands (pancreas, liver). In the organs of the digestive tract (glandular stomach or proventriculus, muscular stomach or gizzard, and the intestine) we found chronic catarrhal inflammation, and also proliferative processes – cellular infiltration of the stroma, overgrowth of the connective tissue. In some cases we also found distrophic processes such as keratinization of the epithelium of the mucous membrane of the glandular stomach. In the pancreas, except for edema of the stroma, no pathological processes were observed. In the liver, we found different types of dystrophy – protein (granular, hydropic) and fatty (infiltrational). With introduction of the highest doses of canthaxanthin used in the experiment, we determined a tendency towards exacerbation of pathological processes, because, apart from the already mentioned changes, we recorded manifestations of alteration (necrotic processes, disorders in blood circulation). Therefore, we proved that irrational use of canthaxanthin in canary-keeping is a factor that can negatively influence the health of these animals. Using the data we obtained, use of canthaxanthin in the diet of canaries can be correlated with their diet, thus avoiding risk of bird diseases. There is scope for further studies on the impact of canthaxanthin on other organs and the systems of the organs at microscopic level, as well as conducting biochemical and morphological analyses of blood, which would allow the creation of a new complete clinical-anatomical description of this pathology.