Why limited
Keep mayo to small, occasional amounts. Sensitive pets may react to it, and sugar- or fat-heavy foods raise the risk of obesity and pancreatitis.
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.
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.
If it ate some before you noticed, watch for vomiting, diarrhoea, loss of appetite, unusual tiredness or a painful, swollen abdomen over the next 24 hours. A one-off small amount in a healthy adult usually passes with water and rest; repeated exposure, a puppy or kitten, a senior, or a pet with an ongoing illness is a reason to call your vet the same day.
Other foods that need limits
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 dogs eat mayo?
CAUTION — limited. 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.
How much mayo can dogs have?
Keep mayo to small, occasional pieces and never part of the main meal. It is classed as with care, so pets with a sensitive gut, pancreatitis or diabetes should skip mayo entirely.
What reaction should I watch for after dogs eats mayo?
In the 24 hours after dogs eats mayo, look for vomiting, diarrhoea, gas or a drop in appetite. 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.
How often can dogs have mayo?
Save mayo for rare moments rather than building it into a routine; your dog may enjoy it, but that alone does not make it fit to feed often.
What are safer treats than mayo for dogs?
Pick from the safe list instead — Basil or Dragon fruit carry none of the risk that mayo does, and they work better as an everyday treat.