Hyperthyroidism in dogs

It is often referred to as an 'overactive thyroid', is when the thyroid gland produces and secretes excessive amounts of the free - not protein bound and circulating in the blood. This is the opposite of hypothyroidism, which is the reduced production and secretion of T3 and/or T4. Very few dogs are diagnosed with hyperthyroidism. It is usually caused by cancer of the thyroid gland. The cancer tumour causes the thyroid to give off too much hormone. This disease usually affects older dogs. Hyperthyroidism may be asymptomatic, but when it is not, symptoms are due to an excess of thyroid hormone. Some of the symptoms of hyperthyroidism are nervousness, irritability, increased perspiration, heart racing, hand tremors, anxiety, difficulty sleeping, thinning of the skin, fine brittle hair, and muscular weakness. When a dog has too much thyroxin, it may lose weight even though it is eating the same amount of food. It may be hungry all the time and bolt its food until it vomits. The dog is often excessively thirsty. It can have diarrhoea and urinate much more often than normal. Major clinical signs include weight loss, anxiety, hair loss, muscle aches, weakness, fatigue, hyperactivity, irritability. Long term untreated hyperthyroidism can lead to osteoporosis. A dog with hyperthyroidism often is irritable and hyperactive because of the excess hormones. Its coat may look shaggy. Weight loss often causes the dog to be too thin and suffer muscle wasting. Though it is overly active at times, the dog may be weak due to the loss of muscle strength and its nervous physical activity.