What foods are toxic to dogs?

The most dangerous: xylitol

Xylitol is an artificial sweetener found in sugar-free chewing gum, certain peanut butters, some yoghurts, protein bars, dental products, and an increasing range of food products. In dogs, even a small amount causes a rapid and severe drop in blood sugar and, at higher doses, acute liver failure. A single piece of xylitol-sweetened gum can be dangerous to a small dog. Read ingredient labels on any human food product before sharing it with your dog. If xylitol has been ingested, call a vet immediately.

Grapes and raisins

Grapes and raisins cause acute kidney failure in dogs, and the toxic mechanism is not fully understood, which means there is no established safe quantity. Some dogs have eaten large amounts without apparent effect; others have had severe kidney damage from a small number of grapes. The unpredictability makes this one of the most dangerous foods because there is no threshold below which you can safely assume your dog is fine. Raisins are more concentrated and therefore more dangerous by weight than fresh grapes. Currants, sultanas, and grape juice are equally dangerous.

Onions, garlic and alliums

Onions, garlic, leeks, chives and shallots all belong to the allium family and all cause damage to dogs' red blood cells, leading to haemolytic anaemia. The damage is cumulative, meaning that regular small exposures can cause harm even if a single serving seems harmless. Cooked, raw, dried or powdered forms are all toxic. Garlic is more concentrated than onion and therefore more dangerous by weight. The symptoms of anaemia, pale gums, weakness and rapid breathing often appear days after the ingestion.

Macadamia nuts, cooked bones, avocado

Macadamia nuts cause weakness, tremors, vomiting and fever in dogs. The mechanism is unknown. Recovery is usually within 48 hours with supportive care. Cooked bones, particularly poultry bones, can splinter and cause internal punctures or obstructions. Raw bones are generally safer but not without risk. Avocado contains persin, which is toxic to dogs in larger quantities, primarily causing vomiting and diarrhoea. The risk is highest from the leaves, skin and stone rather than the flesh, but the flesh is not risk-free.