Are cooked onions dangerous for dogs?

Yes, cooked onions are dangerous for dogs. Onions contain a compound called N-propyl disulfide which can cause Heinz body anemia, a condition in which red blood cells are destroyed. This can lead to weakness, lethargy, vomiting, diarrhea, and even death.

Even a small amount of onion can be toxic to a dog, and can cause anemia in dogs after about 1-3 days after consumption. Cooking the onions does not reduce the toxicity of the compound.

If you think your dog has eaten onions or anything containing onions, it is important to take them to a veterinarian immediately.