Can dogs eat mushrooms from the supermarket?

Cultivated mushrooms sold for cooking are grown in controlled conditions and are not toxic to dogs. White button, chestnut (cremini), portobello, oyster and shiitake mushrooms fall into this group. Rinse them, slice them and cook them plain by steaming, boiling or dry-frying in a non-stick pan.

A few slices are enough: two or three for a small dog, five or six for a large dog.

Raw mushrooms are harder to digest and occasionally cause mild stomach upset. Cooking softens them and makes them easier on the gut. Mushrooms are low in calories, around 22 per 100 g, so they are not a weight concern, but they add little nutrition that complete dog food lacks.

Mushrooms that have gone slimy or mouldy in the fridge should go in the bin, not the dog bowl. Spoiled food can carry bacteria and moulds that upset a dog's stomach. Stuffed mushroom leftovers, garlic butter mushrooms from a takeaway, and mushroom gravy should be treated as unsuitable because of the seasonings.

Garlic mushrooms, creamy mushroom sauces, stroganoff, mushroom risotto and stuffed mushrooms usually contain garlic, onion, butter, cream, cheese or wine. Mushrooms on pizza come with garlic-rich sauce. Keep a few plain slices aside for your dog before any seasoning goes in.

Medicinal mushroom powders and supplements for dogs are a separate topic; speak to your vet before using them. Dried mixed mushrooms from a shop are fine plain once rehydrated, but a bag of unlabelled foraged mushrooms should be treated as wild and unknown.