Cat food for sensitive stomach & hyperthyroid

An 11-year-old Himalayan with loose stools and mild hyperthyroidism managed through diet alone — that's a meaningful combination to navigate carefully. Digestive sensitivity in cats is usually food intolerance rather than true allergy, and limited-ingredient or novel-protein diets tend to work best. The hyperthyroid side adds another layer, since iodine content in food matters when you're managing thyroid function without medication. Can you tell me how long the loose stools have been going on, and what you're currently feeding her?

That timeline and description are useful. Consistently soft stools for three months on the same food usually points to an ingredient intolerance — chicken and chicken by-products are among the most common culprits in cats who've been eating poultry-based food for years. The other thing worth knowing: Hill's Science Plan isn't formulated with iodine restriction in mind, which matters for a cat whose hyperthyroid is being managed by diet. What protein sources has she eaten in the past, and has she ever had a reaction to fish-based foods?

That's helpful — she's a genuinely novel-protein candidate, and fish is a reasonable direction to explore since she has no prior exposure to it. However, given the iodine management angle, I'd steer away from fish-heavy diets as a primary choice, since marine ingredients tend to be higher in iodine. The sweet spot here is a limited-ingredient food with a single novel protein that isn't poultry or fish, in a wet format to support gut transit and hydration in a senior cat. Based on all of that, I'd point you toward Royal Canin Sensitivity Control Duck & Rice in wet pouch form. Duck is a genuine novel protein for her, the ingredient list is short and controlled, it's formulated specifically for digestive sensitivity, and it's relatively moderate in iodine compared to fish-based alternatives. It's also palatable for fussy seniors, which Himalayans often are.

It's a fair question. Rice in small quantities as a carbohydrate source in a therapeutic wet food is generally well tolerated by cats — it's easily digestible, low-allergen, and the amounts in a food like Sensitivity Control are modest. Cats are obligate carnivores so you wouldn't want a rice-heavy dry food as the basis of her diet, but in this context it's working as a digestibility aid rather than a filler. The duck protein is doing the heavy lifting nutritionally.

Go slowly — about ten days total. Start with around 20% new food mixed into her current food for the first three days, then move to 50/50 for another three days, then 80% new for two or three days before going fully over. Himalayans can be stubborn about new textures and smells, so warming the food slightly to just below body temperature can help with acceptance. Given the hyperthyroid management, it's also worth looping your vet in once she's fully transitioned so they can check her thyroid levels — a diet change can occasionally shift how well it's controlled.