Is Garlic Safe for Cats and Dogs?

Garlic use in pets is misunderstood. Garlic can be beneficial and it can be harmful, even fatal. When garlic is harmful, it causes a severe anemia (Heinz body anemia).

Effects of garlic-induced anemia
Anemic cats and dogs develop rapid heartbeats because they don’t have the ability to carry the normal amount of oxygen in their blood. The anemic pet’s heart beats faster in order to circulate oxygen and keep the brain, kidneys, liver, and muscles functioning.

The anemic pet’s bone marrow then tries to produce new RBCs at a rapid rate, pulling nutrients, including iron and B vitamins from their food and tissues. The spleen enlarges as it works to identify and remove all the RBCs that have been damaged by garlic. If the body doesn’t respond and maintain normal hemoglobin levels, the pet will need a blood transfusion in order to stay alive.

Why are cats so susceptible to garlic?
Cats are more susceptible to garlic-induced anemia than are dogs because the cat's hemoglobin is different than the dogs. Hemoglobin is the portion of the RBC that carries oxygen. Molecules within the hemoglobin are oxidized by sulfoxides in the garlic, and this permanently damages the RBC. The spleen sorts the RBC and removes those with damage, so that the pet’s blood is “thinned.” Blood tests show us how “thin” the blood is (hematocrit or packed cell volume) and blood slides show us the Heinz bodies sitting in the red blood cells.

What's the toxic dose of garlic?
The toxic dose for pets is 1-2 cloves/kg, so a 4-kg pet receiving 4 or more cloves a day may die. One teaspoon of garlic powder is equal to a clove. (A garlic clove and a teaspoon of garlic powder weigh about 9 g.) So, 4 teaspoons of garlic powder (36 g) would be toxic to a 4-kg pet, such as your average cat.

What's the safe dose of garlic?
The safe dose of garlic for healthy cats is a slice of garlic clove 2-3 times a week. Although this safe garlic dose is not enough to deworm a pet or cure a viral disease, it probably stimulates the immune system just enough to be a blessing. In addition, garlic provides “heat” from a traditional Chinese medicine (TCM) perspective, and “heat” is beneficial for weak, chilly, or older pets.

My recommendations for garlic
Do I recommend garlic for cats and dogs? Yes. But, the family and I are aware that regular blood tests will help us ensure we’re doing good and not harm. We watch for symptoms of anemia; pale gums, rapid heartbeat, edema, weakness, jaundice. If any of these occur, we look at the pet’s blood and make necessary changes.

Garlic is an example of so many things in life:
more is not necessarily a blessing.