Garlic Toxicity and Pets

A Small Amount Can Be Toxic

Many people consider garlic to be a holistic remedy in the prevention of heart disease, high cholesterol, high blood pressure, warding off fleas and even certain types of cancer.

These potential medicinal benefits, however, are not effective for our pets. In fact, garlic can be toxic to dogs and cats at certain doses and poisoning, if not treated in time, may result in death.

Why is Garlic Toxic to Pets?

Garlic is classified as a species of the Allium family. Other species in the Allium family include onions, shallots, leeks, chives and rakkyo (otherwise known as the Chinese onion).

Garlic, like other members of the Allium family, contain compounds called disulfides and thiosulphates which can be toxic cats and dogs if ingested. The ingestion of garlic causes conditions called hemolytic anemia, Heinz body anemia, and methemoglobinemia which are all manifestation of damage to red blood cells. Essentially, the compounds in garlic can cause the red blood cells circulating through your pet’s body to become very fragile and burst.

How Much Garlic is Toxic to Pets?

“From a toxicity perspective, garlic is approximately 5 times more concentrated than onions,” says Dr. Ahna Brutlag, a board-certified veterinary toxicologist and director of veterinary services at Pet Poison Helpline.

Consider the rule of thumb when it comes to onion toxicity: Consumption of as little as 5 g/kg of onions in cats or 15 to 30 g/kg in dogs has resulted in clinically important red blood cell damage. According to scientific studies, onion toxicosis is consistently noted in animals that ingest more than 0.5% of their body weight in onions at one time.*

Since garlic is more concentrated than an onion, an even smaller ingested amount could lead to toxicosis—as little as one clove of garlic can lead to toxicity in cats and small dogs.

Please note that a pet’s weight, type of breed and prior health history can vary the toxicity level of ingested garlic. If you suspect your dog or cat has ingested garlic, you should contact Pet Poison Helpline at 855-289-0358** or your veterinarian immediately.

Symptoms of Garlic Toxicity in Dogs and Cats

It’s important to note that it may take several days after your pet eats garlic for symptoms to appear.

Symptoms of this condition can include vomiting and diarrhea, along with symptoms of anemia--breathlessness, lethargy, pale, yellow, or “muddy” colored gums, rapid breathing, and an elevated heart rate. Your pet also could develop abdominal pain and discolored urine. While vomiting and diarrhea may occur within one day, it may take several days to a week after your pet eats garlic for symptoms of anemia to appear.

Preventing Garlic Toxicity in Pets

While mass consumption of garlic puts pets at high risk, your pet can also become poisoned after chronic ingestion of small amounts of garlic over a period of time.

Pet owners who believe garlic helps prevent fleas should heed caution.

“The use of garlic as a flea or tick preventative has been researched and found to be ineffective,” says Brutlag. “It is not recommended for this purpose, even in addition to traditional therapies. Not only can it make your pet ill, but it leaves them vulnerable to devastating diseases such as Lyme.”

For pet owners using garlic supplements for themselves, make sure you take steps to protect curious pets. Pet Poison Helpline has had several cases of cats and dogs ingesting garlic pills that were left on the counter. Some needed to be treated for severe anemia.

It’s also wise to keep garlic, onions, chives, and similar foods out of reach. Brutlag recalls a Labrador retriever that ingested ingredients intended for salsa making—fresh garlic, tomatoes, and onions—that were left out on a kitchen table. While the pet owner ran to the store to pick up some last minute extras for the recipe, the dog helped himself to the goods, ingesting at least two bulbs of garlic and several onions. He developed significant anemia and needed a blood transfusion. Luckily, he made a full recovery!

The best advice when concerned about introducing new food or a supplement for your pet is to always consult your family veterinarian first.

Be Ready for Anything

Did you know that you can get comprehensive health insurance coverage for your pet that will reimburse eligible expenses for these conditions? Plus, when you enroll two or more pets, you get an additional discount on your pets' policies. Want to learn more? Click here.

**A per case fee is billed by Pet Poison Helpline. PPH is not affiliated with Nationwide pet insurance.

*Smith K and Schildt J. Onions and Garlic. In Hovda LR, Brutlag AG, Poppenga RH, Peterson, KL eds. Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology. 2nd ed. Ames, IA: Wiley-Blackwell, 2016.