EN
A case of a widespread neoplastic process, originating from the mammary gland in mongrel bitch, weighing 27 kg and aging 7 years, was described. In the patient, blood morphology, blood biochemical parameters, gasometry of arterial blood, chest X-ray, and heart ECG and USG were determined. ECG record demonstrated elevation of ST-T segment by 0.2-0.3 mV in I, aVL leads and a downward- sloping depression in III and aVR leads. The alterations pointed with high probability to infarction in the lateral wall of the left ventricle. Following demonstration by imaging tests of numerous tumours in the chest, the dog was subjected to euthanasia. Upon autopsy, apart from the primary tumour in the mammary gland, numerous tumours were demonstrated in inner organs, including myocardium. Histopathology confirmed neoplastic growth of adenocarcinoma type. In the vicinity of the tumour localised in the left cardiac ventricle, microscopic examination disclosed regions of cardiomyocyte necrosis, which corroborated the preliminary diagnosis of infarction.