Garlic can be poisonous for dogs. Some react differently than others. Just FYI.
Here's what I've learned.
Despite its healing qualities, Garlic contains a compound named thiosulphate. In extremely high levels thiosulphate can be a dangerous toxin that cause hemolytic anemia in dogs. But I'm not talking about garlic dog treats, supplemental garlic, or healthy table scraps that may have included fresh garlic in the recipe. I'm talking about situations where your pet sniffs out several bulbs of garlic you were about to use for a giant batch of homemade spaghetti sauce for the whole neighborhood and winds up eating 50 cloves in one sitting. I repeat . . . it would take up to 50 cloves for garlic to be harmful to your dog! 50 cloves of garlic wouldn’t be a good idea for anyone, let alone your dog. In the event that your dog did get into a basket of garlic cloves, the symptoms of hemolytic anemia can develop within a few hours or a few days. Signs include vomiting, diarrhea, weakness, depression, and loss of appetite. If you see these symptoms in your pet and you're missing a lot of cloves of garlic, call your vet. The bottom line there is that dogs and cats can get into many things around the house that are toxic if consumed in large quantities. But, when used in moderation, garlic can be a healthy supplement.
According to the Whole Dog Journal, small amounts of garlic not only act as a natural flea repellent, but garlic can be used for its wonderful anti fungal and antibacterial properties. It also promotes the production of white blood cells thereby acting as an immune booster for dogs with low or compromised immunity and may benefit dogs with diabetes by helping reduce blood-sugar levels.
In any event, the amount of garlic I give my girl is just what you can put on the tip of a table knife ... not even a clove.