Thyroid Disorder in Dogs
There are two types of thyroid disorders that can occur in dogs. Hyperthyroidism is caused by excessive secretion of thyroid hormones, but occurs very rarely in dogs and is most often a sign of cancer. The more common type of thyroid disorder in dogs is hypothyroidism, which occurs when not enough thyroid hormone is produced.
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Cause
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According to the Merck Veterinary Manual, more than 95 percent of hypothyroidism cases are caused by destruction of the thyroid gland. This destruction is the result of an autoimmune genetic disorder known as lymphocytic thyroiditis.
Symptoms
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Dogs typically begin to show symptoms of hypothyroidism when they are between four and six years old. The disease most commonly affects breeds that are medium to large in size. Affected dogs can show signs of hair loss, dull coat, excessive shedding, thickened skin, changes in skin pigmentation, lethargy and weight gain. Some dogs may also show increased incidence of ear infections, redness and odor.
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Diagnosis
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After a physical examination, your vet will use a diagnostic blood test and thyroid-function test to confirm a suspected case of thyroid disorder.
Treatment
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If your dog is diagnosed with hypothyroidism, your vet will prescribe an oral thyroid supplement. There are two types of hormone medication that can be given to dogs: T3 and T4. The majority of dogs receive T4 hormone because it is naturally converted by the body into T3. Dogs that lack the ability to convert the hormone are given T3. Dosage amounts will be determined by repeating the thyroid-function test until levels are within the normal range.
Considerations
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Your dog will need the supplemental hormone for the rest of her life, and dosage will need to be monitored once or twice annually. Improvement in activity, appetite and attitude can usually be seen within one to two weeks after starting medication. Hair and skin restoration can take up to eight weeks.
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References
- Photo Credit dog image by Michal Tudek from Fotolia.com
