Feline Hyperthyroidism


The cat hasn’t been well lately. Primarily, he has been losing weight. We couldn’t work out why so we took him to the vet. They took some blood and the vet said possibly a thyroid problem.

We got the results the next day and sure enough his thyroid looked to be out of whack. They took more blood which confirmed things.

Hyperthyroidism can be nasty. The symptoms in humans include:

  • Muscle weakness
  • Mood swings
  • Anxiety
  • Sleep disturbance

The symptoms are probably much the same for cats I should imagine.

The treatment options we were offered for Gus were:

  1. Radio iodine – a permanent cure but requires a two-week stay at the vet’s, so we ruled it out as he gets stressed there.
  2. Surgery- again, a permanent cure but he’s old and we didn’t want to put him through it.
  3. Dietary restriction of iodine – expensive and not as good as the option we chose.
  4. Methimazole gel – this is what we settled on. You apply a small amount of the gel to the inside of the ear once a day. The drug suppresses production and release of thyroid hormones. Side-effects are rare apparently. Costs are £34 per  month for the gel, plus about £35 every three weeks for a blood test to check thyroid levels. All things considered, I think we went for the best option.

Hopefully Gus will get well again with no side-effects. Costs per annum will be about £1000, which is quite steep but he’s been a great cat and we don’t mind spending the money.

Edit: I’ve discovered that on methimazole, cats can be expected to live for only 3-5 years after starting treatment. They can also suffer liver damage if their hyperthyroidism is left untreated for too long. More here.


Author: stephen

Software Test Analyst / Technical Author in Scotland.