20 facts about feline hyperthyroidism

Here are some interesting facts about feline hyperthyroidism. What interests me particularly is the increased risk of developing the condition due to exposure to certain chemicals and the fact that full-time indoor cats are at increased risk. I have always felt that there are too many odourless yet poisonous chemicals inside the home in new carpets and in fire resistant products inside sofas etc. which leach out and which can cause health conditions. These are underresearched and more work needs to be done to find the underlying causes of feline hyperthyroidism.

Kiki died of feline hyperthyroidism
Kiki died of feline hyperthyroidism. Photo: Phoenix on Twitter. I dedicate this article to her. RIP.
  1. The first cases of hypothyroidism in domestic cats were reported from the east coast of America in 1979;
  2. West coast cases were reported soon after;
  3. Feline hyperthyroidism cases were reported in Canada, Europe, Australia and New Zealand by 1980;
  4. It was described as an epidemic at the time and the cause remains a mystery;
  5. Certain chemicals and lifestyles increase the risk of becoming hypothyroid;
  6. Full-time indoor cats are four times more likely to develop feline hyperthyroidism than outdoor cat;
  7. When a domestic cat is exposed to lawn herbicides, fertilisers and pesticides the risk of developing the condition is increased by a factor of 3.5;
  8. The risk of getting the condition is increased by 3.4 when fed canned food i.e. wet cat food;
  9. Regular flea treatments increase the risk of getting the condition by a factor of 3.4;
  10. It is said that the condition is most often caused by a non-cancerous tumour. It is also referred to as thyroid cancer;
  11. Elderly cats get it more often than younger cats as the cancers occur in older cats
  12. However, the cause of feline hyperthyroidism is not known but possible contributing factors include deficiencies or excesses of certain compounds in diet and exposure to chemicals in the environment or in the food which disrupts thyroid production;
  13. Hyperthyroidism is an overproduction of thyroid hormone;
  14. Hypothyroidism causes weight loss, increased appetite, restlessness and can be fatal if left untreated;
  15. Sedate older cats suddenly and dramatically act as if they are a kitten
  16. Exposure to second-hand cigarette smoke may be a factor in contracting the condition;
  17. Siamese and Himalayan purebred cats have a lower risk for this problem;
  18. One treatment is an oral medication called methimazole which lowers hormone production and which must be given daily (this may have been superseded by later treatments as this treatment dates to 2008);
  19. Another treatment is surgery to remove the cancerous gland and a third option is to use radioactive iodine to destroy the cancerous tissue.
  20. Caught early before the heart and kidneys are damaged the disease is treatable. See your veterinarian promptly please.

Sources: Dr Bruce Fogle’s Natural Cat Care page 150 – The Endocrine System and Cat Owner’s Home Veterinary Handbook 3rd edition at pages 529-530.


Please note that sometimes videos like the one above stop working because they are removed from the source which in this case is Twitter. I cannot control this potential problem. If it has disappeared, I apologise.

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