The toxic component in garlic and onions for dogs is N-propyl disulfide. This compound, when consumed, can cause oxidative damage to red blood cells, leading to hemolytic anemia. This condition can be fatal if left untreated.
While alliin itself is not directly toxic, it is a precursor to N-propyl disulfide. This means that when garlic or onions are chopped, crushed, or cooked, alliin is converted into N-propyl disulfide.
Therefore, even small amounts of garlic and onions can be dangerous for dogs. While alliin itself may not be the direct culprit, it plays a role in the formation of the toxic compound.
It's important to keep garlic and onions away from your dog, regardless of their form. This includes raw, cooked, powdered, and dehydrated forms.