From the Research
Hyperthyroidism in cats typically presents with weight loss despite increased appetite, hyperactivity, increased thirst and urination, vomiting or diarrhea, unkempt coat, and increased vocalization, as well as rapid heart rate, elevated respiratory rate, and restlessness, with older cats (typically over 8 years old) being most commonly affected. The symptoms of hyperthyroidism in cats can be varied, but common signs include:
- Weight loss despite increased appetite
- Hyperactivity
- Increased thirst and urination
- Vomiting or diarrhea
- Unkempt coat
- Increased vocalization
- Rapid heart rate
- Elevated respiratory rate
- Restlessness Some cats may also develop a palpable thyroid nodule in the neck, and as the disease progresses, they may develop cardiac complications including heart murmurs and hypertension 1, 2, 3, 4. Additionally, some cats may exhibit unusual behaviors like panting or seeking cool places due to heat intolerance. Diagnosis requires blood tests measuring thyroid hormone levels, particularly T4, and treatment options include medication (methimazole, typically 2.5-5mg twice daily), radioactive iodine therapy, surgical removal of the thyroid gland, or prescription diets (Hills y/d) 1, 2, 3, 4. Early detection is important as untreated hyperthyroidism can lead to serious complications including heart failure, kidney damage, and severe weight loss, and regular veterinary check-ups for older cats help catch this condition early when treatment is most effective. According to the most recent study, methimazole may be a more effective treatment option than propylthiouracil in reducing thyroid hormone levels and decreasing the risk of liver function damage, although it may have a higher risk of hypothyroidism 4.