Pathology anatomical changes in the mute swan (Cygnus olor) in the fatal combination of gout and Erysipelotrix rhusopathiae infection

The article presents data from a postmortem examination and a study of the mechanism of death of a mute swan that died from a combination of gout and Erysipelothrix rhusiopathiae infection. The swan was bred and raised in captivity; compound feed for domestic poultry and periodically – minced meat was used in the ration of this bird. The swan died as a result of critical hypothermia associated with a meteorological drop in temperature and high humidity. A month and a half before death, the swan showed signs of hypodynamia, general weakness, poor appetite, and hypothermia. Gout in the swan was diagnosed postmortem. During the autopsy, extensive crystalline chalk-like deposits (urates) were found, in particular, with localization on visceral serous membranes and organ capsules. The most intense urate deposits were localized on the air sacs, liver capsule and pericardium. Pathologies important for the mechanism of swan death were diagnosed in the myocardium (signs of brown atrophy), on the heart valves (urate deposits in the form of massive vegetations classified as crystalline valvulitis) and in the extravalvular areas of the endocardium (sclerotic changes). Massive thrombi were found in the right ventricle of the swan's heart. In the main blood vessels and their visceral branches, total dilatational changes, in particular, caused by cold, are classified. Signs of venous stasis, hemorrhage, capsule ruptures with subcapsular hematomas were found in the liver. Signs of cyanosis, general cachexia, dehydration were observed in the swan. According to the severity of the lesions and their importance in the mechanism of death of the swan, cardiovascular pathology dominated. In the genesis of gout in the dead swan, dietary factors (protein-rich feed), hypodynamia and dehydration played a key role. Erysipelothrix rhusiopathiae was found based on the results of genetic and molecular research of swan liver and spleen samples.