Can cats eat salmon?

How the salmon is prepared changes the answer

Almost the whole answer lives in what is on the plate before your cat gets to it.

Why raw salmon is the form to skip

Raw is where the near-term risk sits. VCA lists Salmonella, Listeria monocytogenes, Campylobacter, E. coli, Yersinia enterocolitica and several Clostridium species among the bacteria found in raw pet food, and notes that nearly a quarter of raw food samples in one study tested positive for harmful bacteria. A cat can shed those bacteria in saliva and feces while looking perfectly well, which puts everyone else in the house in the way of it. Cornell’s position on raw meat as a food or a treat for cats is simply that it is not recommended.

What thiaminase is, and whether salmon carries it

Raw fish is the classic dietary cause of thiamine deficiency in cats. The mechanism is an enzyme called thiaminase, which cleaves thiamine and leaves it biologically useless. Merck places thiaminases in raw freshwater fish and clams, where they “produce a deficiency by rapid destruction of dietary thiamine”.

Salmon is a slightly awkward fit for that story. A 2023 review that gathered thiaminase activity data for 300 fish species found the enzyme concentrated in the herring and carp orders, and did not list salmon among the fishes that produce it. The case against raw salmon is mostly the bacteria, not the enzyme.

The two sources also differ on how far cooking settles the question. Merck is flat about it: thiaminases are destroyed by cooking, which is why canned commercial cat food can contain fish without any thiamine risk. The thiamine review in the veterinary literature is more guarded, saying thiaminases are denatured by high heat “with varying sensitivity”, and that the risk can remain in inadequately cooked fish-based diets. Both agree that heat helps. They disagree on whether it finishes the job. Cook salmon right through rather than leaving the center rare.

What a fish-heavy diet does to a cat

Cats are obligate carnivores, so a plate of fish looks like the right idea. The trouble is not the protein, it is everything a single ingredient leaves out.

Two deficiencies are documented in cats fed mostly fish. Thiamine is the one raw fish drives, and Merck describes the result as anorexia, failure to grow, neurologic dysfunction, seizures and muscle weakness. Vitamin E is the other. Merck records naturally occurring vitamin E deficiency in cats given large quantities of canned tuna, ending in pansteatitis, also called yellow fat disease. A 2003 case series in the Journal of Feline Medicine and Surgery found the same thing in eight cats fed mainly oily fish: inappetence, depression, reluctance to move, and subcutaneous nodules that hurt to touch. Every one of those cats recovered on treatment and a change of diet except one.

None of this argues against salmon. It argues against salmon at meal size. Cornell’s rule of thumb is that treats should not exceed 10 to 15 percent of a cat’s daily calories, and the other 85 to 90 percent needs to be a food carrying an AAFCO statement, which is what tells you it is complete and balanced.

Signs of the two fish-diet deficiencies

These come on over weeks of a fish-dominated diet, not after a stolen mouthful.

Thiamine deficiency is mostly neurological:

• Going off food, and kittens failing to grow
• Weakness and unsteadiness on the feet
• Head held oddly low, with the neck bent down towards the chest
• Flicking eyes, a slow pupil response to light, loss of vision
• Collapse and seizures

Vitamin E deficiency, as pansteatitis, looks different:

• Loss of appetite and a flat, withdrawn mood
• Reluctance to move
• Pain when you touch the belly
• Lumps under the skin in fatty areas

Any of these deserve a vet appointment, and take the diet history with you. What your cat has actually been eating is the thing that points a vet at either of these, and neither is obvious from the signs alone.

If your cat has just eaten raw or smoked salmon

A single stolen piece is a different situation from a fish diet. The deficiencies above turn up in cats fed mostly fish over time, and one mouthful will not produce them.

What one piece of raw salmon can do in the short term is upset the gut. Watch for vomiting, diarrhea, and refusing food. Call your vet if any of that starts, if your cat seems dull or sore, or if the salmon was cooked with onion or garlic, which are a separate problem from the fish. Bones are worth a call on their own, because ASPCA warns they can cause injury or an obstruction that needs surgery.

Fish is one of the most common food allergens in cats

Merck names beef, fish and chicken as the most common food allergens in cats, so salmon is not a neutral choice for a cat with itchy skin. The usual sign is itching rather than an upset stomach, most often around the face, ears and neck, sometimes with miliary dermatitis or eosinophilic granuloma lesions.

If a new itch appears after salmon becomes a regular treat, tell your vet what you have been feeding. There is no quick test for this. The reference standard is a strict elimination diet run for at least 10 weeks, then a deliberate rechallenge to confirm it, so the sooner the diet history is on the record the shorter that process gets.