Effects of Cushing's syndrome, diabetes and feline hyperthyroidism on the cardiovascular system of small animals.

Abstract

This literature review discusses the cardiovascular effects of three common endocrinopathies in small animals: diabetes mellitus, Cushing's syndrome, and feline hyperthyroidism. These diseases, which are also common in humans, share pathophysiological mechanisms and are relevant due to their impact on the cardiovascular system. Diabetes mellitus can induce diabetic cardiomyopathy characterized by ventricular hypertrophy, diastolic dysfunction, and myocardial fibrosis. It is also associated with systemic hypertension, especially in dogs, and complications such as diabetic ketoacidosis (DKA). Cushing's syndrome in dogs, caused by pituitary or adrenal tumors, leads to excessive cortisol production, causing myocardial hypertrophy, diastolic dysfunction, systemic hypertension, and myocardial fibrosis. These alterations can develop even without obvious systemic hypertension. In addition, there is a predisposition to thrombosis and vascular abnormalities. In cats, Cushing's syndrome is rare but can present with similar manifestations. Feline hyperthyroidism, the most common endocrinopathy in geriatric cats, causes cardiovascular abnormalities such as tachycardia, ventricular hypertrophy, diastolic dysfunction, a gallop rhythm and systemic hypertension. These are due to the effects of thyroid hormones on metabolism and myocardial contractility. Although many of these disorders are reversible with treatment, their association with hypertrophic cardiomyopathy and arterial thromboembolism has been documented. Thyroid strom, a life threatening complication of feline hyperthyroidism, is also discussed, although it is not fully understood in veterinary medicine.