Garlic is widely regarded as a safe and healthy supplement. So, it’s frequently added to many commercial dog foods and treats. Garlic’s claimed benefits include:
- Anti-bacterial properties
- Flea and worm control
- Digestive support
However, some warn that garlic is toxic to dogs and should never be added to an animal’s diet.
With so much at stake, it’s important to question both the positive and negative effects of garlic — before deciding whether or not to make it a staple in your dog’s daily menu.
The Case for Garlic
In the following video, Dr. Deva Khalsa, a holistic vet, presents the argument for garlic. And even though she’s obviously promoting her nutritional supplements, Dr. Khalsa makes a solid case for feeding controlled amounts of garlic to a dog.
However, many pro-garlic claims have never been proven — and are only considered possible benefits for humans.
Take, for example, garlic’s most popular homeopathic claim that it naturally prevents fleas, worms and other parasites.1
Despite the abundance of products that utilize garlic as a means to control fleas, research supporting its effectiveness is lacking.
Toxic in Large Doses
There are also specific health risks associated with garlic. That’s because like other species in the Allium family, onions and garlic contain aliphatic sulfides.
And when eaten by a dog, these same sulfides can produce telltale inclusions of denatured hemoglobin — the oxygen transport molecule — found within the animal’s red blood cells.
These so-called Heinz bodies can burst and decrease the numbers of red blood cells in the animal — a dangerous condition known as hemolytic anemia.2
And in acute cases, garlic poisoning can lead to nausea, vomiting, diarrhea, elevated heart rate, weakness or even collapse.3
That’s why garlic is considered toxic to dogs and cats by the…
to Blood Cells
Fans of garlic would argue that it can take a significant amount of the ingredient to produce the kinds of clinical effects seen with this type of anemia.
And that’s true — at least for clinical signs. Keep in mind — these are the signs of disease that can be easily seen with the naked eye.
However, what about subclinical signs — the invisible damage seen only with the help of a microscope or lab tests?
In this video, Dr. John Tegzes, a veterinary toxicologist, warns about the damage that can be done to a dog’s red blood cells:
According to another vet toxicologist, Dr. Sharon Gwaltney-Brant, even in small amounts, garlic has demonstrated a proven ability to cause subclinical damage to a dog’s red blood cells.4
And in a peer-reviewed article, Allium poisoning was found to not only follow the consumption of a single large amount of material but also after repeated smaller doses.5
The Bottom Line
When used in larger doses, no one will argue that garlic and onions can be toxic to dogs. Yet one must also think about the potential health risks in feeding smaller amounts, too.
On the other hand, with many years of safe use behind it, garlic’s universal acceptance among pet lovers cannot be ignored.
So, be sure to consider the pros and the cons of feeding garlic on a daily basis when making your next dog food purchase.
- Pitcairn RH, DVM, PhD, Dr. Pitcairn’s Complete Guide to Natural Health for Dogs & Cats (2005), page 384 ↩
- Yamato et al, Heinz Body hemolytic anemia with eccentrocytosis from ingestion of Chinese chive (Allium tuberosum) and garlic (Allium sativum) in a dog, Journal of the American Animal Hospital Association 41:68-73 (2005) ↩
- Garlic, Poison List, Pet Poison Helpline, Animal Poison Control Center ↩
- Sharon Gwaltney-Brant DVM, Veterinary Toxicologist, Vice President and Medical Director, ASPCA Animal Poison Control Center in an interview with Dr. Bernadine D. Cruz for Pet Life Radio, Pets Have a Real Taste for Danger ↩
- Cope RB, BSc, BVSc, PhD, Allium species poisoning in cats and dogs, Toxicology Brief, ASPCA Professional pp. 562-564 (2005) ↩