Garlic is widely used in human food but rumors say it can be toxic in dogs. Let’s see the evidence:
Garlic is approved for use in pet foods and recognized as safe (GRAS) by the FDA and AAFCO but its use in dog treats remains controversial. The compound in garlic, allicin, is responsible for its antimicrobial properties. Allicin degrades with heat and processing so processed garlic contains allicin present in lower concentrations than in fresh garlic. (Allicin in dried garlic is approximately 6.0 mg allicin/gram dry mass). Allicin is also found in onions, leeks, and chives. Chopping, crushing, or grinding garlic causes allicin to form.
Most dog treat products contain dehydrated, processed garlic which tends to cause allicin concentrations to be decreased because of the processing. So dehydrated garlic appears to be safer than fresh garlic because of the reduced amount of allicin. The enzyme, catalase, needed to detoxify garlic is present in low amounts in dogs. It appears that red blood cells in cats are more susceptible to damage from garlic. But the dose of garlic is still the most important factor in its toxicity. Certain breeds such as English Setters, Whippets, and Boxers appear to be more sensitive to red blood cell changes that can result in low blood pressure, increased heart rate and weakness. This can occur within 24 hours or several days later after ingestion. Wild garlic, considered “natural” is also in this toxic category emphasizing that “natural” doesn’t always mean safe! There are a few case reports of dogs consuming amounts of fresh garlic such as 60 grams of baked garlic, 22 cloves of garlic in a 10# dog, etc. but it is generally felt that the inclusion of dehydrated garlic in dog treats does not pose a health risk to dogs.