Overview
Hyperthyroidism (thyrotoxicosis) is a condition where the thyroid glands produce too much thyroid hormone, usually due to a benign thyroid gland tumor, and generally affects middle-to-older-aged cats. Since the thyroid hormone controls the body’s metabolism, an overproduction of this hormone causes an increase in the body's metabolic activity and often results in some or all of the following symptoms:
- Increased appetite, thirst and urination
- Diarrhea
- Weight loss
- Fast or difficult breathing
- Heart problems
- Irritability or hyperactivity
Some animals actually decrease their food intake and become quieter (apathetic), however this is an uncommon manifestation of this syndrome. The symptoms of hyperthyroidism mimic a variety of other potential conditions, so your veterinarian will likely take a blood and urine sample for evaluation.
Diagnosing Hyperthyroidism in Cats
Diagnosis is made by performing a physical examination, obtaining a history, assessing blood levels of thyroid hormones, taking X-rays or performing echocardiography, and if results are equivocal, special suppression and stimulation hormone tests are carried out.