Hypothyroidism in Dogs
Definition of Hypothroidism
Hypothyroidism occurs when the thyroid gland doesn’t make enough of two essential hormones, triiodothyronine (T3) and thyroxine (T4). Primary hypothyroidism is the most common form of this disease and usually is caused by inflammation and atrophy of the thyroid gland. For some reason, the dog’s immune system targets and damages its own thyroid tissue as if it were foreign. This decreases the amount of T3 and T4 circulating in the bloodstream, triggering a cascade of metabolic problems. Environmental and dietary factors may also be involved. Secondary hypothyroidism, which is rare in dogs, can be caused by systemic disease, dietary iodine deficiency and space-occupying pituitary gland tumors, among other things. Hypothyroid dogs can have a variety of symptoms, including mental dullness, lethargy, weakness, exercise intolerance, weight gain for no apparent reason, heat-seeking behavior (they get cold easily), symmetrical hair loss without itchiness, ear infections and assorted skin and coat abnormalities. Fortunately, hypothyroidism is fairly easy to diagnose and treat.
Primary hypothyroidism is the most common form of this disease and typically is caused by lymphocytic thyroiditis or idiopathic thyroid gland atrophy. These conditions involve immune-mediated destruction of or damage to the thyroid gland. For some reason, the affected dog’s immunologic defense mechanisms target its own thyroid tissues, as if they were foreign. Over time, circulating T3 and T4 levels diminish, causing a cascade of metabolic abnormalities. Environmental and dietary factors are possible contributors to
Hypothyroidism occurs most frequently in large, middle-aged dogs of either gender and of any breed or mixed breed. The symptoms of hypothyroidism are often nonspecific and quite gradual in onset, and they frequently vary based upon the dog’s breed and age at the time of onset of thyroid hormone deficiency. Although the signs of hypothyroidism can be subtle, most affected dogs have one or more of the following symptoms:The dog’s neuromuscular, reproductive, cardiovascular and/or gastrointestinal
Canine hypothyroidism is not difficult to diagnose. In fact, it is one of the most overdiagnosed diseases of domestic dogs, mainly because the symptoms of hypothyroidism mimic those of so many other disorders.When presented with a dog showing some of the classic signs of hypothyroidism, a veterinarian will typically perform a complete blood count, a serum biochemistry panel and a urinalysis, as part of an initial database. The results of these tests can be suggestive
Hypothyroidism is a condition caused by abnormally low circulating levels of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). It is a relatively common problem in mid-to-large-sized, middle-aged dogs of either gender and often is accompanied by vague, nonspecific symptoms that mirror those of other diseases. Once hypothyroidism is definitively diagnosed, it can be treated fairly easily, although treatment must continue for the dog’s lifetime. The goals of treating hypothyroidism are to restore normal levels