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It’s not uncommon to find contradictions when searching for canine health advice. But nowhere do these contradictions run deeper than with the question, “Can dogs eat garlic?”
It’s not just the internet that’s divided on this question, either. Take a look at published, peer-reviewed scientific studies, and you’ll find just as many that caution against garlic supplementation as those that tout it as a wonderful health stimulant. And the confusion doesn’t stop there. Just about all vet-approved “Toxic Foods for Dogs” lists will include garlic, yet many well-known dog food manufacturers put powdered garlic in their recipes.
So, is garlic safe for dogs? Or poisonous?
The answer, as you can imagine, is a little muddled. Below, we’ll dive deep into the topic of feeding garlic to dogs, when it’s dangerous, why it can be beneficial, and how to do it safely.
Understanding Garlic Toxicity In Dogs
It’s not always easy to figure out where a rumor got started. But when it comes to the canine garlic toxicity myth, the source is well established.
In 2000, a group of researchers in Japan did a study to test the effects of garlic on dogs. They fed a small group of mixed-breed dogs garlic extract for seven days. During the test period, they did blood draws to look at different health markers and found that supplementation with garlic had oxidative effects on red blood cells and caused anemia. From these findings, they concluded that “foods containing garlic should not be fed to dogs.”
The problem? The amount of garlic these dogs were given each day was equivalent to feeding about ¼ clove of garlic per pound of body weight. That means a dog weighing 50 pounds would need to consume a full head of garlic every day to see these same results. Not even a human could eat that much garlic without getting sick. (Interestingly though, while the dogs showed changes in labwork, no clinical signs of illness were reported.)
When dog food manufacturers add garlic powder to their recipes, the amount they use makes up less than 0.2% of the total dry matter. The amount the dogs in the above study were given is closer to 11%.
Luckily, we have more recent and more realistic studies to look at to understand the actual risks of feeding dogs garlic. In 2018, a different group of Japanese researchers gave lab beagles a small dose of aged garlic extract daily for 12 weeks and found zero negative effects.
The amount administered in this study was significantly lower than the amount in the original study and represents a more appropriate garlic dose for dogs.
Symptoms of Garlic Poisoning in Dogs
So, is garlic safe for dogs? In low amounts, yes. But in high doses, it can cause issues, especially with the digestive tract and red blood cells.
There have been a handful of documented cases of dogs eating large amounts of garlic and getting sick. One schnauzer consumed an entire head of baked garlic and suffered vomiting, dark urine, anemia, and eccentrocytosis for about four days after symptoms began. The dog recovered well after treatment but continued to have high blood pressure for four months following the incident.
If you believe your dog has eaten an excessive amount of garlic, it is wise to bring them straight to the vet.
Signs of garlic poisoning in dogs include:
- Vomiting
- Diarrhea
- Weakness
- Loss of coordination
- Red or brown urine
- Increased heart and respiratory rate
- Pale or blue gums and skin
Garlic toxicity is most likely when a dog consumes large amounts of garlic powder, garlic supplements, fresh garlic, and baked garlic. Aged garlic extracts and supplements have much lower sulfur content and are considered safer for dogs, but should still only be given in reasonable amounts.
The Benefits of Garlic for Dogs
Like humans, dogs can benefit from garlic consumption so long as they are fed an appropriate amount.
The unique compounds in garlic are associated with:
- Improved cardiovascular health. Eating garlic can reduce blood pressure in people and dogs with existing hypertension. This potent herb can also prevent the hardening of blood vessels and reduce cholesterol levels, which lowers the risk of cardiac events.
- A stronger immune system. Researchers in the 2018 beagle study we looked at above, found that the aged garlic extract they used affected pathways in the immune system to reduce inflammation and increase antioxidant enzyme activity. Human studies have shown that garlic supplementation can reduce cold and flu rates and that garlic may have antiviral activities.
- Reduced tumor formation. Multiple studies have shown that garlic prevents the formation of tumors and may have anti-cancer effects.
- Cognitive health. The antioxidants in garlic have been found to support healthy brain activity, reduce symptoms of dementia, and protect against cognitive decline.
- Body detoxification. Many studies support garlic’s ability to detoxify the body of heavy metals, especially lead.
- Reduced parasitic infections. Garlic is widely used as an intestinal and topical parasite treatment in humans and dogs around the world.
- Bone health. Multiple studies have shown that garlic use reduces oxidative stress throughout the body. One osteoporosis study found that this effect can help prevent bone loss.
- Reduces the risk of blood clots. Garlic contains natural anti-platelet compounds and can help reduce blood clots in dogs with a history of this issue.
In addition, garlic is a nutrient-dense food, providing high levels of manganese, vitamins B6 and C, selenium, and fiber.
Using Garlic as an Alternative Medicine
While giving your dog garlic daily in small amounts is likely safe and may have some small nutritional benefits, the more effective way to use garlic is as a pointed treatment for specific issues.
Flea and Tick Treatment
Adding fresh garlic to your dog’s meals during the summer can greatly reduce how many ticks they bring home and their risk of flea infestation.
The potent oils in garlic are believed to make your dog taste less appealing to these topical parasites. Indeed, many commercial natural flea and tick supplements utilize garlic as a pest repellent.
It is most effective to start giving your dog garlic a few weeks before flea and tick season so it has a chance to build up in their system. When feeding garlic, always use raw garlic (more on this below). Start by giving it to your dog daily for about two weeks, then administer it twice a week for the rest of the season.
You can also use powdered garlic to keep fleas out of outdoor kennels and to reduce flea numbers in areas where your dog frequents. Because this powder has a notable odor, I suggest using diatomaceous earth, another effective natural flea treatment, instead of garlic powder when treating kennels, bedding, and carpets inside the home.
Treatment for Internal Parasites
Garlic has long been used as a natural anti-parasitic in livestock, and many studies support its effectiveness against nematodes, tapeworms, and roundworms.
While studies have been done less frequently in this area on dogs, there is some evidence that feeding garlic to dogs drastically reduces the number of eggs and larvae present in the stool. These effects were only found during active treatment with garlic, however, suggesting that garlic must be given daily to effectively reduce intestinal parasite activity.
Anti-Cancer Supplement
Studies of garlic supplementation in humans, dogs, and mice have shown that the compounds in this potent herb may reduce the risk of many gastrointestinal and respiratory cancers.
While there are not enough of these clinical studies to say for sure how effective garlic might be in treating or preventing cancer, there are plenty of anecdotal and regional studies to support its use.
Cultures that use garlic frequently in cuisine have a lower incidence of cancer across the board. And the historical use of garlic in specific regions is associated with lower cancer and tumor rates.
If your dog is fighting cancer, it is absolutely worth speaking to your holistic veterinarian about adding a garlic supplement to their treatment. But be aware that garlic interacts with a number of medications, including chemotherapy drugs, so talk to your vet first.
Use as an Antiviral and Antibacterial
The sulfuric compounds in garlic have a strong capacity to fight viruses and bacteria in and outside the body.
Garlic is frequently featured as an ingredient in natural ear infection treatments. Garlic oil can be beneficial for topically supporting your dog’s ear health. It can also be used to treat infections in minor wounds and to prevent infections in raw skin caused by rashes and topical allergies.
Many studies have proven that garlic reduces the number of colds and other common viral diseases in humans. Supplementing with garlic can help your dog avoid common communicable canine respiratory diseases, including kennel cough. It may also help fight internal bacterial infections of the intestines and lungs.
Garlic is also great for maintaining a healthy gut biome, as bad bacteria are far more susceptible to it than beneficial bacteria. However, dogs with poor gut health will have a harder time breaking down the fructans in garlic, which can cause digestive side effects. Before using garlic as a supplement for any reason, help strengthen your dog’s gut biome and improve their gut health by feeding a biologically appropriate diet, using a quality probiotic supplement, and taking steps to reduce inflammation.
Proper Dosing Is the Key to Safety
Hopefully, it’s obvious to you now that garlic in itself is not dangerous for dogs. Garlic becomes risky when it is given in high doses. But the quantity of garlic is not the only important thing to consider. The quality and type of garlic counts, too.
Garlic contains a number of compounds, some of which can be toxic in concentrated amounts and many of which change depending on how the garlic is processed and how long it has been since it was processed.
When using garlic for its medicinal properties, it is important to use only fresh, raw garlic. And, just as important, to use it within about ten minutes of crushing it.
This is because raw whole garlic contains an enzyme called alliinase and an amino acid called alliin. When you crush (or mince) garlic, these two compounds begin to react to create allicin. This product is the compound in garlic that gives it its “magical” medicinal properties.
It is also the compound most readily lost when garlic is dried into garlic powder, extracted into garlic extract, and turned into oil.
Not only does fresh, raw, recently crushed garlic contain the most allicin, but it also contains hundreds of other compounds with notable health benefits. Not to mention that fresh garlic tends to be cheaper and more readily available than “garlic supplements,” so there’s really no reason not to use it!
Garlic Dosage for Dogs
There is some wiggle room in what constitutes a safe garlic dose for dogs. But in general, ⅓ tsp of minced garlic per 10 pounds of body weight is a good place to start.
| Dog’s Weight | Garlic Dose per Day (fresh minced) |
| 5 pounds | ⅙ tsp |
| 10 pounds | ⅓ tsp |
| 15 pounds | ½ tsp |
| 20 pounds | ⅔ tsp |
| 30 pounds | 1 tsp |
| 40 pounds | 1 ⅓ tsp |
| 50 pounds | 1 ⅔ tsp |
| 70 pounds | 2 ⅓ tsp |
| 90 pounds | 3 tsp |
| 110 pounds | 3 ⅔ tsp |
How to Supplement with Garlic
The key to ensuring your dog gets all the benefits from garlic without the risks is to only use fresh garlic and to mince it and let it sit for about ten minutes before adding it to your dog’s food.
Any shorter and alliin and alliinase don’t have time to react. Any longer and you start to lose that volatile allicin compound.
In general, you’ll want to give this dose two to four times per week. You can also give it daily for a restricted period (usually about two weeks) if you’re targeting an infection or building up the garlic in your dog’s body in preparation for flea and tick season.
Now, you may be tempted to reach for one of the few garlic supplements for dogs on the market. While these are unlikely to hurt your dog, they will certainly not be as potent as fresh garlic.
On a similar note, many people wonder if garlic powder is safe for dogs. Again, any product marketed for dogs and given according to the package directions is likely safe, though less effective than fresh. Garlic powder from the spice aisle, on the other hand, poses more of a risk. The potency of these products can vary greatly. One teaspoon of powdered garlic can have as much thiosulphate (the compound that causes anemia at high doses) as four teaspoons of minced garlic.
When to Not Give Your Dog Garlic
While garlic is generally safe in small amounts, there are times when you should skip it altogether, including:
- Dogs with anemia – Dogs that have anemia, red blood cell disorders, or bone marrow disorders should not use garlic as it can further reduce red blood cell count.
- Dogs on certain drugs – Garlic can interact with many prescriptions, including immune suppressants, insulin, chemo drugs, heart meds, blood thinners, and high blood pressure meds.
- Puppies – Do not give puppies under 6 months garlic. For puppies older than 6 months, give half the normal dose until they are fully grown.
- Pregnant or nursing dogs – As always, use caution here.
The Final Word on Garlic for Dogs
Rest assured, doggy owners everywhere, garlic in reasonable quantities is perfectly safe to give to healthy dogs. In fact, it has many known benefits and can even be used as an alternative medicine to treat fleas, certain infections, some cancers, and common respiratory illnesses.
Just remember, the key to using garlic safely and effectively is to give the correct dose based on your dog’s weight and to use only freshly minced garlic or a garlic supplement intended for dogs.
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Sara Seitz worked in the pet industry for over a decade. In addition to being a certified dog trainer, Sara gained experience working as the general manager of a dog daycare and boarding facility, as the creator and manager of a pet sitting company, as a groomer, and as a dog behavior evaluator. She also has a bachelors in animal behavior from CSU. Currently, Sara works as a freelance writer specializing in blog, article and content writing.
