Doctor - do you recommend y/d diet for cats with thyroid disease (hyperthyroidism)?
Thanks for your question. I personally don't have enough experience with this food over enough time to provide a strong recommendation. I also asked several veterinarians and they also have not had any enough experience to have a definitive conclusion. I'll tell you below what I recommend.
First - let's review Hyperthyroidism. Hyperthyoidism is a common disease of senior cats that is caused by an unregulated overproduction of thyroid hormone by the thyroid glands, which is usually related to a benign enlargement (growth or tumor) of one or both thyroid lobes. This enlargement of the thyroid gland(s) is referred to as thyroid adenoma or thyroid adenomatous goiter. The cause is unknown. For more information on common symptoms - go to: Hyperthyroidism in Cats.
Hyperthyroidism in cats is most commonly treated with medications (e.g. Methimazole (Tapazole®)), surgical removal of the abnormal thyroid lobe or radioactive iodine therapy. All treatments are directed at controlling excessive secretion of the thyroid hormones.
Hill's developed a diet called y/d. The Hill's website says “Prescription Diet y/d is the safe, effective and easy way to manage thyroid health. Clinically proven nutrition to restore thyroid health in 3 weeks.”
This sounds great. But until more is known, I would not recommend that it be used on as the sole treatment in cats with severe symptoms of hyperthyroidism. It may be a good treatment to augment medical therapy in pets that are not candidates for surgery or in pets with very mild disease. If the dietary therapy is used, routine thyroid blood levels should be monitored to determine treatment success.
Best of luck,
P.S. For more information on the diet - go to: //www.hillspet.com/products/pd-feline-yd.