Every dog is different. Individual allergies and sensitivities are common — always introduce new foods in small amounts and watch for adverse reactions. This site is for informational purposes only and is not veterinary advice. Always consult your vet.
The Full Picture
Plain mayonnaise is not toxic to dogs, but it is extremely high in fat and calories while offering virtually no nutritional benefit. A single tablespoon of mayonnaise contains around 10 grams of fat, which can contribute to weight gain and increase the risk of pancreatitis, particularly in smaller breeds and dogs prone to the condition. Some mayonnaise products contain additional ingredients such as garlic, onion, lemon juice, or mustard, which can be harmful. Low-fat or diet mayonnaise may contain artificial sweeteners including xylitol, which is extremely toxic. If your dog accidentally eats a small amount of plain mayonnaise, it is unlikely to cause serious harm, but it should never be offered as a treat.
What You Should Know
While mayonnaise is not outright toxic, there are important precautions to bear in mind before sharing it with your dog. Portion size matters, and certain preparations or varieties may be unsafe. If your dog has any existing health conditions, check with your vet first.