What to do if your pet ate it
Contact your vet or a poison line right away, report how much mayo was eaten and your pet's weight, and keep any packaging or leftovers. Do not induce vomiting unless your vet tells you to.
Signs to watch for
- Vomiting and diarrhoea
- Lethargy and weakness
- Loss of appetite
- Severe: tremors, breathing trouble, collapse
If your pet shows vomiting, lethargy or any unusual behaviour after eating mayo, go to the nearest emergency vet immediately.
Dogs are rated “Feed with care” and cats “Do not feed”. If both share the house, go by the stricter of the two when you decide what to hand over.
Other foods that are toxic or dangerous
The full A–Z food list groups every food by verdict for each species.
Why these cautions matter
Garlic and onion damage a pet's red blood cells and can bring on anaemia. Signs are often delayed for several days, so looking fine straight afterwards does not rule it out.
Rich, fatty food is the classic trigger for pancreatitis, a painful inflammation of the pancreas that usually needs veterinary treatment rather than rest alone.
Frequently asked questions
Can cats eat mayo?
NO — do not feed. Commercial mayonnaise contains egg yolk, oil, vinegar and often onion or garlic powder. Dogs can tolerate a small spoonful but the high fat may cause gastrointestinal upset or pancreatitis; avoid if it contains onion/garlic. Cats are very sensitive to onion/garlic toxins, so even trace amounts make mayo unsafe for them.
What if my cat already ate mayo?
Call your vet or a poison line now with the amount of mayo eaten and your cat's weight, and do not induce vomiting unless a vet tells you to. If mayo was eaten and you then see vomiting, lethargy, tremors or breathing changes, go straight to the nearest emergency clinic.
Is there a safe amount of mayo for cats?
There is no accepted safe dose of mayo for cats; it is classed as toxic or dangerous, and reactions vary with the individual animal, so it is not something to feed at any amount.
How often can cats have mayo?
mayo is not something to feed at any interval; it stays off the menu entirely.
What are safer treats than mayo for cats?
Pick from the safe list instead — fresh catnip or hamburger carry none of the risk that mayo does, and they work better as an everyday treat.