Obesity is a metabolic disorder, in which excess fat accumulates in the body. Fat in the cat's body can be deposited with abundant feeding of the animal and its small mobility. The cause of obesity may be a lack of pituitary hormones. At a cat with obesity there is a fast fatigability, drowsiness, there is a dyspnea. The animal begins to suffer from increased appetite and thirst. Heart failure may develop. Obesity is of two types: exogenous and endogenous. In the first case, the fat is deposited evenly. In the second, fat is deposited in the neck, chest, abdomen and perineum. The diagnosis is made by the doctor on the basis of clinical signs and the dynamics of weight gain. The main thing in the treatment of obesity is the appointment of dietary nutrition, reduction in the diet of the cat the amount of carbohydrates and fats, increasing physical exertion. Diabetes mellitus is characterized by absolute or relative insufficiency of insulin in the cat's body. With absolute insulin deficiency, the level of insulin in the blood decreases because of a violation of its synthesis. Relative insulin deficiency is the result of a decrease in insulin activity. Deficiency of insulin in the body leads to violations of carbohydrate, protein and fat metabolism. There is an increased synthesis of cholesterol, the formation of protein and antibodies is reduced. There is a large loss of fluid, which leads to dehydration of the body. Cats are given boiled meat, fish, oatmeal, mineral water.