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By Judyvein Cheng, CPCN, BRNC
Certified pet nutritionist in Singapore
QUICK ANSWER
Garlic is one of the most debated foods for dogs. In large amounts it can damage red blood cells, but fed fresh, raw and in the right amount, many holistic practitioners use it for its benefits, including keeping fleas and ticks away. The difference between help and harm is the dose and the source. And some dogs shouldn't have it at all.
Why garlic has a bad reputation
Garlic appears on many lists of plants that are poisonous to dogs, but much of the research behind those warnings uses very high doses. In one study (Lee et al., 2000), dogs were given 5g of garlic extract per kg of body weight every day for 7 days. For a 34kg (75lb) Golden Retriever, that's about four whole heads, or 60 cloves, a day. Even a 4.5kg (10lb) dog would need about 23g, or 6–8 cloves, before adverse effects appeared.
In contrast, a later study (Yamato et al., 2018) gave dogs aged garlic extract at 90mg per kg daily for 12 weeks with no adverse effects. Garlic actually boosted the dogs' own antioxidant defences.
One of my mentors, clinical canine herbalist Rita Hogan, puts it simply: garlic is a wonderful plant. What matters is where it comes from and how much you give.
The benefits
Garlic is packed with nutrients: inulin, amino acids, sulphur, zinc, potassium, phosphorus, vitamins A, C and B-complex, calcium, magnesium, manganese, selenium and germanium. It's antifungal, antiparasitic, antioxidant, antibiotic and anticancer.
✓ Fleas and ticks: they dislike the smell, which builds up in the coat oils after about 2 weeks of regular feeding.
✓ Antifungal and antiparasitic: its compound ajoene has antifungal, antiparasitic and antitumour effects, and may help rebalance yeast overgrowth like candida.
✓ Heart and circulation: alliin and the enzyme alliinase combine to form allicin, which supports the heart. Garlic also dilates blood vessels, helps prevent platelets from clumping, helps regulate blood pressure and lowers unhealthy cholesterol.
✓ Immunity: boosts natural killer cells.
✓ Gut and liver: supports beneficial gut bacteria and liver function, and acts as a gentle seasonal detox.
✓ Heavy metals: according to researcher Rajdeep Chowdhury, garlic helps bind and reduce lead, cadmium, methylmercury and phenylmercury.
✓ Anticancer compounds: S-allylmercaptocysteine promotes cancer cell death, and diallyl disulfide (DADS) helps prevent gut cancers by calming inflammation. Population studies by the US National Cancer Institute link higher garlic intake to a lower risk of colon, lung, stomach and rectal cancers, though clinical trials are still few.
✓ Lymphatic support: helps clear lymph stagnation and improve elimination.
Who should avoid garlic
✓ Akitas and Shiba Inus: genetically more sensitive to the compounds in garlic (thiosulphates and N-propyl disulphide) that can cause Heinz body anaemia. If you're unsure about your dog, consider genetic testing or talk to a holistic vet.
✓ Puppies: never at 8 weeks or younger, and avoid under 6 months. From 6 months to 1 year, use half the regular dose.
✓ Pregnant dogs: check with a holistic vet first.
✓ Nursing dogs: avoid, as garlic changes the taste of the milk.
✓ Dogs with leaky gut, IBD or IBS: garlic's fructans can cause bloating, gas and constipation. Heal the gut first. Read more in is your pet's digestion healthy?.
✓ Dogs on medication: immunosuppressants, heart or blood pressure medication, chemotherapy, blood thinners, insulin or antacids. Don't combine garlic with these.
✓ Before surgery: stop garlic 2 weeks before, as it affects blood clotting.
Warning signs of a reaction: diarrhoea, dark urine, loss of appetite, yellow gums or eyes, lethargy, pale gums, a fast heartbeat or laboured breathing. See your vet immediately.
Choosing and preparing garlic
Strictly fresh, raw, organic garlic only, grown without pesticides or glyphosate. Avoid garlic from China, which has tested positive for arsenic, heavy metals and chlorine. In Singapore, you can find organic garlic on RedMart.
Avoid shortcuts: pre-chopped garlic in jars and bags of peeled cloves aren't suitable. Aged garlic extract (such as Kyolic) contains no allicin.
Peel, then chop, mince or crush, and let it sit for 10–15 minutes so the allicin can form.
Mix it into food straight away, since allicin breaks down quickly.
Avoid garlic oil and capsules, because their dose is hard to control. Organic granulated garlic is acceptable, but it lacks some of the benefits of fresh garlic.
How much and how often
Fresh chopped garlic: 1 level tsp per 13.6kg (30lb) of body weight, always rounding down.
2.3kg (5lb): 1/6 tsp · 4.5kg (10lb): 1/3 tsp · 6.8kg (15lb): 1/2 tsp · 9kg (20lb): 2/3 tsp · 13.6kg (30lb): 1 tsp
Organic granulated garlic: extra-small dogs 1/16 tsp, small 1/8 tsp, medium 1/4 tsp, large 1/2 tsp, extra-large 3/4 tsp.
Start low. Always begin with a smaller amount than the guide, crush and chop the garlic finely, and mix it really well into the food. If you notice any signs of acid reflux, cut down the dose.
A general rule: every dog is an individual, your dog's dose isn't "a dog's" dose. Always start lower, and stop increasing at the point your dog tolerates well.
How often: in Singapore, flea season can last all year round. If your dog tolerates garlic well, I recommend starting with 2–3 times a week, then adjusting to less often if needed. Since the coat takes about 2 weeks to build up protection, start before you expect fleas, and keep bathing to a minimum. When you do bathe, use a gentle, natural shampoo like 4Legger Revitalize Neem Shampoo.
Canine energetics: garlic is pungent, warming and drying. It moves energy up and out, improves circulation and has an affinity with the lungs, large intestine, spleen and stomach. Long-term use can dry the body's tissues, so dogs who run warm and dry shouldn't have it too often.
Prefer a ready-made option? Glacier Peak Holistics Daily Defense contains garlic as part of its daily parasite support formula.
FROM MY EXPERIENCE
Both my dogs have had garlic, but at very different frequencies, because of their energetics.
Wangcai was a warm dog, so he only had a little garlic once a week.
BeanBean is slightly cool but dry, so she can tolerate more, especially when her diet is more damp in energetics. She has garlic 2 times a week.
Frequently asked questions
Is garlic toxic for dogs?
In large amounts, yes. In small, measured amounts of fresh garlic, for the right dog, it can be beneficial.
What about onions, chives and shallots?
These are toxic to pets. Stay away from them completely.
Can I give garlic every day?
Some protocols use daily feeding for a short period, but for ongoing use I recommend 2–3 times a week, adjusted to your dog's tolerance and energetics.
Garlic can be a helpful addition for the right dog, at the right dose. If it isn't right for your dog, there are other herbs that can help too.
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This article is for educational purposes and isn't a substitute for veterinary care. If you're concerned about your pet's health, please seek professional advice.
ABOUT THE AUTHOR
Judyvein Cheng, CPCN, BRNC
Judyvein is a Certified Professional Canine Nutritionist and Certified Raw Nutrition Coach for Cats & Dogs, and the founder of JOOF Holistic Pet. Her journey began with her Frenchie, Wangcai, and today she helps pet parents in Singapore take a root-cause approach to their pets' health.
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