Hey Annette!

I checked into natural hyperthyroid remedies for cats and found zero. I found plenty for humans and looked into whether they might apply to your cat, as often many remedies can apply across species. This is what I found.

The cause for hyperthyroidism in cats is, in most cases, due to a benign tumor on the thyroid. This is not the reason why humans have hyperthyroid so the human remedies would not apply. The remedies for treating your cat's hyperthyroid range from radioactive iodine injected into the tumor, to big pharmameds to shrink the tumor, to surgery which appears to resolve the condition entirely.

Sources:

http://www.aspca.org/pet-care/cat-care/hyperthyroidism

http://catinfo.org/?link=felinehyperthyroidism

What I also learned is that the symptoms for feline hyperthyroid also closely resemble that of feline diabetes and renal failure - among others.

If you knew for certain you were dealing with a tumor on the thyroid, a castor oil pack or castor oil and turmeric in a pack over the thyoid might help; seabuckthorn oil might help; turmeric added to the food might help; and Essiac tea would also be a remedy to consider.

What concerns me most, however, would be to treat your kitty for the wrong condition - castor oil packs over the thyroid gland, when you kitty is actually ailing from diabetes. So fearing that, I urge you to read up on feline hyperthyroid and seek out at minimum a blood panel from your vet to look for the overt markers for feline hyperthyroid before you attempt any home treatment.

I am trying out Thyroid Support Gold, an herbal remedy for my cat's hyperthyroidism. You can look it up online, it has bugleweed and lemon balm, which has been found to help the condition. My vet says the herbs are safe for cats, so does not hurt to try it. Many say that it helps.