Toxic Foods for Dogs: A Complete Guide
Understanding which foods are harmful to your dog is one of the most important things you can do to keep them safe. Many common household foods — from fruit and sweets to cooking ingredients — can cause serious illness or even death in dogs. This guide covers the most important toxic foods for dogs in the UK, explains the risks, and tells you what to do if your dog eats something harmful.
Grapes, Raisins, Sultanas and Currants
These are among the most dangerous foods for dogs. Even a small amount can cause acute kidney failure. The toxic compound has not been identified, meaning there is no safe dose. All forms — fresh grapes, dried raisins, sultanas, and any food containing them — must be kept away from dogs. Hot cross buns, Christmas pudding, fruit cake, mince pies, and trail mix are common sources.
Chocolate and Theobromine
Chocolate contains theobromine, which dogs metabolise slowly, allowing it to accumulate to toxic levels. Dark chocolate and baking chocolate are the most dangerous. Symptoms include vomiting, muscle tremors, rapid heart rate, and seizures. Even small amounts can be harmful to small dogs or puppies. Seasonal risks are highest at Easter, Christmas, and Halloween.
Xylitol — The Hidden Sweetener
Xylitol is a sugar substitute found in sugar-free chewing gum, mints, some peanut butters, toothpaste, baked goods, and vitamins. It causes a rapid and severe drop in blood sugar (hypoglycaemia) in dogs and can also cause acute liver failure. Symptoms appear very quickly — within 15 to 30 minutes in some cases. Always check labels for xylitol, and never give your dog sugar-free products intended for humans.
In the UK, xylitol may appear on ingredient lists as E967 or 'birch sugar'. It is increasingly common in protein bars, flavoured vitamins, mouthwash, and even some products marketed as low-calorie dog treats. The dose that causes toxicity can be very low — approximately 0.1 grams per kilogram of body weight for hypoglycaemia, and higher amounts can cause liver failure. If you are unsure whether a product contains xylitol, check the full ingredient list before offering it to your dog.
Onions, Garlic, Leeks, and Chives
All allium vegetables damage red blood cells in dogs, leading to haemolytic anaemia. Cooked, raw, and powdered forms are all toxic. Garlic is more concentrated than onion and is not safe in any amount despite some myths suggesting it has health benefits for dogs. Cumulative exposure over multiple meals can cause toxicity even if no single serving was large.
Macadamia Nuts
Macadamia nuts cause weakness, tremors, vomiting, hyperthermia (elevated body temperature), and difficulty walking in dogs. The exact mechanism is not yet fully understood. Symptoms typically appear within 12 hours of ingestion and usually resolve within 48 hours, but veterinary treatment may be needed. Even small quantities can be problematic.
Alcohol
Dogs are far more sensitive to alcohol than humans. Even trace amounts of beer, wine, spirits, or foods cooked in alcohol can cause vomiting, disorientation, breathing difficulties, and dangerously low blood sugar. Never offer alcohol to a dog, even as a joke, and keep alcoholic drinks out of reach. Fermented foods such as rising bread dough, overripe fruit, and unsecured home brewing equipment are also common sources of accidental alcohol exposure. If your dog shows signs of intoxication — staggering, extreme lethargy, or collapse — treat it as an emergency and contact your vet immediately.
Avocado
Avocado contains persin, a compound found throughout the fruit, stone, skin, and leaves. While dogs are somewhat less sensitive to persin than birds or rabbits, ingesting significant amounts — particularly the stone — can cause vomiting, diarrhoea, and potentially more serious effects. Avocado guacamole often also contains onion and garlic, making it doubly dangerous.
Blue-Green Algae
Blue-green algae (cyanobacteria) blooms in stagnant ponds, lakes, and rivers — particularly in warm weather from July to October across the UK. Dogs that swim in or drink from affected water can be exposed to potent toxins that cause rapid liver failure, neurological symptoms, and death. Never let your dog swim in or drink from water with visible surface blooms or a strong musty smell.
Cooked Bones
Cooked bones of any kind — chicken, beef, lamb, pork — become brittle and splinter easily. Bone fragments can lacerate the mouth, throat, oesophagus, stomach, and intestines, causing internal bleeding or perforation. Raw meaty bones are softer but still carry choking and bacterial risks. If you want to give your dog something to chew, choose veterinary-approved dental chews or raw bones under direct supervision.
When in Doubt, Check First
The foods covered in this guide represent the most commonly documented causes of dog poisoning in the UK, but the list is not exhaustive. Other foods to be cautious with include nutmeg (toxic in significant quantities), wild mushrooms (some UK species are highly toxic), stone fruit pips and apple cores (contain cyanogenic compounds), and very salty foods which can cause sodium ion poisoning. Before giving your dog any food you are unsure about, use TreatCheck to check it. If you believe your dog has already eaten something potentially toxic, contact your vet immediately — do not wait for symptoms to appear. Early treatment significantly improves outcomes for most toxic ingestions.