Garlic for Dogs

Garlic for Dogs: Delicious, Healthy, and Controversial

We are all familiar with garlic as we often use it to flavor the meals we prepare and eat. Using garlic for dogs is possible, with caution.

Garlic is an Allium

It is an edible bulb and part of the allium family. Other foods in the allium family are leeks, onions, chives, scallions, and shallots.

Plants in the allium family contain N-propyl disulfides and thiosulfates. These compounds can cause damage to the red blood cells of dogs and cats but not humans.⁸

So why do we even want to talk about garlic for dogs? Because small amounts of garlic may be very helpful and not harm your dog.

Garlic’s Benefits for Dogs

Let’s look at the science and health benefits behind this flavorful bulb.

Allicin is the compound thought to provide health benefits. It is formed by two enzymes found in garlic cloves. The first alliin is a nonvolatile, odorless sulfur. The second, alliinase is a pungent, volatile sulfur compound.⁴

Alliin is unstable and heat can reduce its yield, so we’re looking at raw garlic’s benefits, not cooked garlic.

Human Studies on Garlic’s Anti-Cancer Benefits

Human studies on garlic as an anti-cancer supplement have had mixed results.

• Some studies have shown that homemade garlic extract can inhibit growth of cancer cells in vitro (in the lab) including breast cancer and multiple myeloma.⁵
• Another paper noted that while garlic may reduce cancer growth more studies are needed, and the amount needed to lower the risk of developing cancer is unknown.⁴
• Epidemiological studies on esophageal, liver, pancreatic and biliary tract cancer found anticancer effects of garlic and in vitro studies revealed cell proliferation inhibition, apoptosis, control of invasion, decrease of angiogenesis, and a reduction of harsh chemotherapy side effects.⁵

Canine Studies on Garlic’s Anti-Cancer Benefits

An in vitro study on canine mammary cancer found garlic to be effective in reducing the growth of canine mammary tumor cells.⁷

Another study on long-term oral administration of garlic extracts in dogs at dose of 90 mg/kg/day for 12 weeks did not show any adverse side effects in dogs. They also found upregulated phase II antioxidants that suggests garlic might safely contribute to the health of dogs provided the use of appropriate dose.⁶

With All These Benefits, Why Is Giving Garlic to Dogs Controversial?

As noted above, dogs are sensitive to the compounds N-propyl disulfides and thiosulfate found in Alliums plants. When metabolized, these compounds cause oxidative damage to the red blood cells causing anemia, which can be severe.

This website is about dogs but just a quick feline sidebar: cats are not small dogs, and they are VERY sensitive to allium toxicity so do not ever feed your cat garlic.

Garlic is the most potent of the allium plants. It is 5 times more toxic than onions and leeks.⁸ Garlic can also cause gastrointestinal issues including gastric ulceration, vomiting, and diarrhea.¹

Well, that sounds distressing, doesn’t it? That’s where the controversy is. Garlic can be toxic, but as with all substances, the dose matters. In the case of garlic, more is not better.

How Much Garlic is Too Much Garlic for Dogs?

There is some documentation that even in small doses garlic in some dogs can have toxic effects, but it is more common with larger amounts or with regular ingestion.¹

The true toxic dose of garlic is not fully known as various studies have had conflicting findings. The AKC mentions that a dog 15-30 grams of garlic per kilogram of weight is needed to have toxic effects, while other veterinary literature says 3-6 grams per kilogram is enough to be toxic.⁸

The average garlic clove is 5grams. So, for a 25-pound dog that would mean anywhere between 6 cloves and 60 cloves may cause an issue. That is a really wide range; as you can see, the data is a little bit murky!

What About Garlic Powder for Dogs?

Keep in mind that garlic powder is much more concentrated (approximately 8 cloves per teaspoon) so a small amount can be much more dangerous than a similar amount of raw garlic.

What’s the Real Risk?

In general, small amounts of garlic infrequently are less likely to cause toxicity in dogs but large amounts, garlic salts, or frequent administration carries a higher risk.

Studies have found that Japanese dog breeds including Akitas, Shiba Inus, and Japanese Chins are more sensitive to allium induced oxidative damage on red blood cells so do not feed these breeds garlic. It is also best to avoid feeding pregnant dogs or puppies garlic.⁹

Garlic in Flea and Tick Preventatives

Garlic is also often an ingredient in natural flea and tick preventatives. It is unclear how much garlic is in some natural flea and tick prevention products so please consult a vet if you wish to feed your dog garlic supplements for flea and tick prevention.

Also keep in mind that there is inconclusive evidence regarding garlic as an effective parasite prevention.²

Signs of Garlic Toxicity

It’s rare for dogs to eat enough garlic to make themselves sick, but you should be aware of the signs a dog has had too much garlic.

Signs of garlic toxicity are lethargy, weakness, ataxia, pale gums, vomiting, increased heart and respiratory rate, red/brown urine, hyper-salivation, and blue tinged gums.¹

Where to Get Garlic for Dogs

Garlic is generally sold as whole cloves at grocery stores. Raw garlic is preferred. Garlic can be grown organically or traditionally. Organics tend to have less chemical residue but there is no known difference in the availability of allicin based on growth practices.

Garlic can also be purchased canned or in salt form. The salt/powder form of garlic is more concentrated so smaller amounts may cause issues.¹

It also comes in capsule form as a supplement. If you are considering using a supplement form of garlic, ask your veterinarian for the right dose for your dog, and be careful to give only that amount.

How to Prepare Garlic for Your Dog

Preparation of garlic involves removing the papery outside of the bulb and mincing the cloves which then can be fed raw whole, minced, or cooked with other foods.

How Much Garlic to Feed Your Dog

Remember there are risks with feeding garlic, but there are also benefits. If you stay under the commonly noted toxic dose of 5 g/kg (each clove is around 3-7 grams) you will have less of a chance of causing adverse effects.

To be conservative, staying under 3 g/kg and not feeding it on a consistent basis will reduce the change of adverse effects even further. This translates into around 1-2 cloves (depending on their size) per 10 pounds of body weight.

Always speak to your vet first about your dog’s specific situation before adding garlic, just to make sure they are not sensitive to it or already suffering from anemia.

When Not to Feed Garlic to Your Dog

• Do not use garlic if your pet is already anemic due to the stress garlic can put on red blood cells.
• Do not use in Japanese dog breeds that are more susceptible to red blood cell damage such as the Akita, Shiba Inu, and Japanese Chin.
• Do not use in large amounts.
• Do not use in young or pregnant animals.

In general, it is best to check with your veterinarian before use.