Hypothyroidism is a common health problem in dogs. It is an endocrine disease that affects the production of hormones in the body. It is most common in young and middle-aged dogs and can cause a range of symptoms. If it is not treated, it may progress to seizures.
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Function
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The thyroid is one of the largest endocrine glands in the body. It is located in the neck of a dog and shaped like a butterfly. The thyroid is responsible for controlling the metabolism by producing hormones. The hormones that the thyroid produces are called triiodothyronine (T4) and thyroxin (T3). They help regulate a dog's metabolic system and are responsible for hair growth.
Hypothyroidism
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Hypothyroidism is a condition in which the thyroid does not produce enough of these hormones. Most cases of hypothyroidism are caused by the impaired ability of the thyroid because of the destruction of it by the dog's immune system. The mechanism for this immune system response is unknown. In some cases, hypothyroidism can be caused by certain medications.
Symptoms
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The symptoms of hypothyroidism are varied and can include weight gain or obesity, hair loss, high cholesterol, and lethargy. The dog's coat may appear thin and dry, and he may shed excessively. The dog may demonstrate intolerance to cold. In some cases the dog may be less alert and active. In rare cases neurological problems may develop, such as seizures.
Seizures
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A seizure is an involuntary behavior that occurs abnormally. Some of the signs of seizures in canines can include stiffness of muscles, loss of consciousness, shallow breathing, drooling, and lack of bowel and bladder control. Hypothyroidism is believed to causes seizures because the lack of thyroid hormones causes high cholesterol. This causes a condition called cerebrovascular atherosclerosis, characterized by hardening in the arteries. Over time the arteries become completely blocked, which causes a lack of blood supply to the brain. It can lead to central nervous system abnormalities such as seizures. It is also believed that hypothyroidism may precipitate or aggravate an existing seizure disorder. Treatment is necessary so that hypothyroidism does not progress to seizures.
Treatment
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Hypothyroidism is treated with synthetic thyroid medication such as thyroxine (levothyroxine). The dosage depends on factors such as the dog's age and weight. Careful monitoring and frequent blood work is necessary so that the medication is in the correct therapeutic range. This medication must be taken for the duration of the dog's life.
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