Feeding My Hyperthyroid Cat

The best diet for your hyperthyroid cat satisfies his/her nutritional requirements as an aging carnivore recovering from a muscle-wasting disease, and avoids chemicals that may contribute to thyroid disease. We encourage you to read cat food labels and consider these guidelines.

It is best to feed:


Canned or raw diets, that contain little to no fruits, vegetables, or grains. Any canned cat food is better than most dry options, which contain too much plant-based protein and carbohydrates. Meat by-products are fine for carnivores; they are simply protein sources such as organ meats and entrails that people do not find appetizing. Gravy foods tend to be high in carbohydrates, so patés are a better choice.

Motivated clients may check out the website, which gives nutrient breakdown of various prescription and over-the-counter diets in the link “Protein/Fat/Carbs Chart”. It turns out that many of the OTC canned diets have an acceptable composition of these, and are reasonably low in phosphate, i.e.:

  • >40% meat protein (>12g/100 kcal)
  • <10 % carbohydrates
  • 50 % fat
  • <250 mg/100kcal phosphate

Note: these percentages are based on dry matter, metabolizable energy, unlike those on the can label.

It may be best to avoid:

  • SOY-containing foods
  • BPA in canned food linings
  • Plastic food and water bowls (replace with glass, ceramic or metal)
  • Storing food in plastic containers
  • Ultra-high or ultra low iodine diets
  • y/d® diet, Hills®

Note: All hyperthyroid cats need to eat as much as they possibly can*. Offer food ad lib, and if you have a cat, heavy or thin, that refuses new diets, stick with what they will eat best. Sometimes gradually transitioning them from less-than-optimal diets to more nutritionally suitable ones works.

*If your cat is overweight, we do not recommend unrestricted calories, even before treatment here. However, we do still recommend to switch your cat to a fully wet/canned diet. Consult with your primary veterinarian about specific diet and amounts to feed.

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