HYPOTHYROIDISM IN DOGS

This is a disease of thyroid deficiency. Dogs with hypothyroidism have metabolic rates below normal. Hypothyroidism, in most cases, is caused by autoimmune thyroiditis (also called lymphocytic thyroiditis), which results in destruction of thyroid tissue. Autoimmune thyroiditis is known to be an inherited disease. The disease occurs most often in middle-aged dogs of medium and large breeds, but has been seen in virtually every breed and in mixed breeds as well. The breeds most commonly affected are the Golden Retriever, Doberman pinscher, Irish Setter, Miniature Schnauzer, Dachshund, Cocker Spaniel, Labrador Retriever, Greyhound. Hypothyroidism is the most common endocrine skin disease in dogs-but it is still less common than other skin diseases. Coat and skin changes are bilateral and symmetrical. A typical sign is poor hair regrowth, which is most noticeable after the dog has been clipped. . Other signs of hypothyroidism include weight gain, intolerance to cold, a slow heart rate, and absence of heat cycles, lethargy, and a variety of nonspecific symptoms. Hypothyroid dogs may develop blepharitis, corneal ulcers, deafness, constipation, and anaemia. At least two-thirds of hypothyroid dogs have high serum cholesterol levels. Behaviour changes including aggression have also been noted in hypothyroid dogs, particularly German Shepherd Dogs. The recommended blood test for screening purposes is the total T4. A normal T4 is fairly conclusive evidence that the dog does not have hypothyroidism. However, a low-normal or below-normal level does not mean the dog is hypothyroid, because concentrations below normal are common for many reasons other than hypothyroidism.