| Verdict for dogs | Caution |
| Severity | 2 / 5 — Mild — usually stomach upset; watch them. |
| Safe amount | A taste at most |
| Category | Human snacks |
| Source | ASPCA Animal Poison Control — People Foods to Avoid Feeding Your Pets · reviewed 2026-08-07 · confidence: medium |
Mayonnaise is not toxic but is almost entirely fat — enough of it can cause vomiting, diarrhea or pancreatitis, which the ASPCA lists as the risk from fatty foods. Aioli and garlic mayo are worse because of the garlic.
Don't make it a habit. Watch for vomiting, diarrhea or a lost appetite over the next day and call your vet if it doesn't settle or your dog seems unwell.
Never induce vomiting and never give any medicine unless a vet tells you to — it can do more damage than the poison. What we will and won't tell you.
If you're sharing food because you want to treat them, a treat formulated for dogs does the job without the guesswork.
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Can cats eat mayonnaise? — Feed with caution to cats.
Not toxic, but be careful — mayonnaise isn't poisonous to dogs, and it comes with caveats that matter. Mayonnaise is not toxic but is almost entirely fat — enough of it can cause vomiting, diarrhea or pancreatitis, which the ASPCA lists as the risk from fatty foods. Aioli and garlic mayo are worse because of the garlic.
Watch for: Repeated vomiting; A painful, tense belly — some dogs stretch into a 'praying' position; Loss of appetite and lethargy; Diarrhea. Some signs lag by a day — call, don't wait.
The safe amount is a taste at most, as an occasional treat rather than a daily habit. Large amounts mainly cause stomach upset; if that doesn't settle within a day, call your vet.