How poisonous are onions to dogs?

The amount of garlic or onion a dog needs to consume before it gets sick is very individual and depends on one case to the other. In general ca 5g of garlic/kg bodyweight and 15-20g onion/kg bodyweight is poisonous to dogs. It does not matter what type of onion the dog consumes; whether it is raw, dried or cooked, it is still poisonous. Dried onion (such as powder) is more concentrated than raw produce; the dog only needs to eat small amounts in order to get poisoned. It is best to avoid any products that contain onions. If your dog accidentally eats a small piece of sausage that contains onion powder it is unlikely to cause problems. However, serious consequences may arise if you frequently give your dog products that contain garlic/onion over a long period of time.

Onions and garlic contain a substance that damages red blood cells resulting in anaemia and an inability to transport oxygen around the body.