Dear Doctor July 2022


Garlic for warding off fleas and ticks?

You said in a recent issue that garlic is toxic for dogs. Why, then, do some companies sell garlic tablets and granules to be ingested by dogs for flea and tick control?

James Edwards
Alto, New Mexico

Dear Mr. Edwards,

We don’t recommend using garlic to ward off fleas and ticks for a couple of reasons, despite the fact that some companies sell garlic products for that purpose. One reason is scientific proof that it works is lacking. An article in the journal Veterinary Evidence points out that even after a scouring of the scientific literature, not a single peer-reviewed study that involved giving garlic to dogs for the purpose of insect control could be identified. All of the evidence at this point is hearsay.

Furthermore, garlic is toxic to dogs. It destroys red blood cells, which can make a dog very sick. A minute amount is unlikely to be harmful, but what is minute is going to be different for a Great Dane and a Chihuahua, and different from one Chihuahua to the next.

Combine that with the fact that unlike drugs, supplements do not require the U.S. Food and Drug Administration to review product effectiveness, safety, or quality prior to marketing, and you’re really playing Russian roulette with your dog’s health. The amount of garlic stated on the label might not even be the amount actually in the supplement.

Why not go with one of the medicines prescribed by your dog’s vet? We understand the appeal of using something “natural,” but the drugs for canine flea and tick control have been evaluated in carefully conducted studies for efficacy and safety before they ever reach your hands.


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