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.

CANINE THYROID DISEASES

Canine thyroid disease can be tough to diagnose. The symptoms can be: lethargy, weight gain, dull coat, skin infections, constipation, diarrhoea, cold intolerance, skin odour, hair loss, dry skin, reproductive problems, aggression, and more. The associated conditions can be serious: mega-oesophagus, ruptured knee ligaments, testicular atrophy, excessive bleeding, and corneal ulcers. The disease can be inherited or of unknown origin. Thyroid gland Endocrine glands secrete hormones that help manage the body’s processes. The thyroid gland lies on the dog’s trachea, just below the larynx; tri-iodothyronine and levo-thyroxine, the hormones produced by the thyroid, govern the body’s basic metabolism — including control of growth and development and maintenance of protein, carbohydrate, and lipid metabolism — throughout life. The most common cause of canine thyroid disease is autoimmune thyroiditis. It is an immune-mediated process that develops in genetically susceptible individuals and is characterized by the presence of anti-thyroid antibodies in the blood or tissues. Thyroiditis is believed to start in most cases around puberty, and gradually progress through mid-life and old age to become clinically expressed hypothyroidism once thyroid glandular reserve has been depleted. During this process, the animal becomes more susceptible to immune-mediated or other diseases affecting various target tissues and organs.