Can Cats Safely Eat Tuna
Many cat owners wonder if sharing a can of tuna is a harmless treat or a dangerous mistake. While tuna is not toxic to cats in small amounts, it is not a nutritionally complete food and carries specific health risks when fed regularly. This article explains the clinical facts, common questions, and safe feeding guidelines so you can make an informed decision for your feline companion.
Quick Q&A: Common Questions
Question: Can cats safely eat tuna every day?
Answer: No. Feeding tuna daily can lead to mercury poisoning, thiamine deficiency, and nutritional imbalances. Tuna lacks essential nutrients like taurine and vitamin E that cats need for heart, eye, and immune health. The American Veterinary Medical Association (AVMA) and the European Medicines Agency (EMA) advise that tuna should only be an occasional treat, not a dietary staple.
Why Tuna Is Not a Complete Food for Cats
Cats are obligate carnivores, meaning they require specific nutrients found only in animal tissues. Tuna is a protein-rich fish, but it does not provide a balanced diet. A cat eating only tuna would miss critical nutrients such as:
- Taurine: An amino acid essential for heart function, vision, and reproduction. Tuna contains some taurine, but not enough to meet a cat’s daily requirement.
- Vitamin E: Tuna is low in vitamin E, and a deficiency can cause steatitis (inflammation of body fat), a painful condition.
- Vitamin B1 (Thiamine): Tuna contains an enzyme called thiaminase that breaks down thiamine. Chronic feeding can lead to thiamine deficiency, causing neurological signs like wobbliness, seizures, or loss of appetite.
The Canadian Veterinary Medical Association (CVMA) and the Australian Veterinary Association (AVA) both recommend that commercial cat foods be formulated to meet AAFCO or FEDIAF standards. Tuna alone does not meet these standards.
Health Risks of Feeding Tuna to Cats
Mercury Poisoning
Tuna, especially larger species like albacore (white tuna), can accumulate high levels of methylmercury. Chronic exposure in cats can cause:
- Neurological signs: ataxia (loss of coordination), tremors, blindness
- Gastrointestinal upset: vomiting, diarrhoea (or diarrhea)
- Kidney damage
The European Food Safety Authority (EFSA) has set tolerable weekly intake limits for mercury in humans, and similar caution applies to pets. Feeding tuna more than once a week increases the risk of mercury accumulation.
Thiamine Deficiency
As mentioned, thiaminase in tuna destroys thiamine. Signs of thiamine deficiency include:
- Anorexia (loss of appetite)
- Dilated pupils
- Head tilting or circling
- Seizures
This condition is reversible if caught early, but it requires veterinary intervention and thiamine supplementation.
Nutritional Imbalances
Tuna is high in phosphorus and low in calcium. Over time, this can contribute to kidney disease in susceptible cats, especially older ones. Additionally, tuna packed in oil or brine adds unnecessary fats or sodium, which can cause pancreatitis or hypertension.
How to Safely Offer Tuna as a Treat
If you want to give your cat tuna, follow these guidelines from the AVMA and AAHA (American Animal Hospital Association):
- Choose the right type: Use tuna packed in water (not oil or brine) with no added salt, seasonings, or flavours.
- Limit frequency: Offer no more than one tablespoon (about 15 grams) once a week. For a small cat, even less is better.
- Avoid canned tuna for human consumption as a meal: It is not nutritionally complete. Instead, use a small amount as a topper for your cat’s regular balanced diet.
- Watch for signs of intolerance: Some cats are sensitive to fish and may develop vomiting, diarrhoea, or skin allergies. Stop feeding tuna if you notice any adverse reactions.
What to Do If Your Cat Eats Too Much Tuna
If your cat has eaten a large amount of tuna (for example, an entire can), monitor for signs of gastrointestinal upset. Most cats will be fine, but contact your veterinarian if you see:
- Repeated vomiting or diarrhoea
- Lethargy or weakness
- Loss of appetite for more than 24 hours
- Neurological signs like stumbling or tremors
Your vet may recommend supportive care such as fluids or anti-nausea medication. In cases of suspected mercury toxicity, blood tests can measure mercury levels, though this is rare with occasional exposure.
Prevention: Building a Healthy Diet
The best way to keep your cat healthy is to feed a complete and balanced commercial cat food that meets AAFCO (US), FEDIAF (Europe), or CVMA (Canada) standards. Tuna should be reserved as an occasional treat, not a dietary staple. If your cat is a picky eater, consult your veterinarian for advice on transitioning to a balanced diet without relying on tuna.
International Consensus
Veterinary organisations worldwide agree on the risks of feeding tuna to cats. The AVMA, AAHA, CVMA, AVA, and FVE/EMA all caution against regular tuna feeding due to mercury, thiamine deficiency, and nutritional imbalances. The consensus is clear: tuna is safe as an occasional treat but not as a primary food source.
Final Thoughts
Cats can safely eat tuna in very small amounts as an occasional treat, but it should never replace a complete and balanced diet. The risks of mercury poisoning, thiamine deficiency, and nutritional imbalances make daily feeding unsafe. By following the guidelines above and consulting your veterinarian, you can keep your cat healthy while still offering an occasional taste of tuna.