June 20, 2016
The issue of garlic toxicity has become a recurrent topic of discussion in the animal supplements industry— mainly because most of what is stated in the toxicology/poison center databases (including ASPCA and others) , none of which include discussions of inappropriate dosing or what constitutes misuse. This, coupled with the fact that the FDA and the Association of American Feed Control Officials (AAFCO) list garlic as “generally regarded as safe” for consumption in both humans and animals, has created a great deal of confusion about this wonderful herb.
So to clarify….
The first thing to keep in mind is that toxicity is always dose dependent. Virtually everything we, or our animals ingest can be toxic if consumed in two much excess. Garlic is no exception.
While it is true that gross misuse of garlic can lead to a serious, sometimes life-threatening condition known as “Heinz body anemia”; a condition that causes an acute deformity of red blood cells and a reduced ability to transport blood oxygen, the circumstances required to reach that side effect generally involves continuous feeding of excessive amounts of garlic (or onions), with total disregard of many lesser side effects— such as nausea/vomiting, flatulence, diarrhea and lethargy. In other words, one would have to continue feeding the herb in gross over abundance, while disregarding many other obvious symptoms of toxicity. One study I have read claims that a healthy 30 pound dog would have to eat 5 ounces of raw onion of garlic per day, likely for several days, before manifesting Heinz-body symptoms. After that the feeding would still have to continue— despite the retching, farting and/or diarrhea— to reach a lethal level. And in most cases, the blood will repair itself to normal structure and functions after feeding is terminated.
Of course this isn’t to say that some dogs or other animals (humans are not excluded) may be hypersensitive to the herb. But, to add even more “true life” perspective to the issue, I recently pulled adverse event data from the National Animal Supplement Council (NASC) Adverse Event Reporting System; the most advanced system of its kind in the world. Even big pharma can’t compare. NASC requires all of its manufacturer members— about 90% of the entire animal supplements industry— to upload each and every ingredient of every product formula they manufacture and sell, into the NASC-AER system. That’s over 1400 ingredients in all! Each manufacturer is also required to report each and every adverse event they learn about into the system— ranging from a simple case of drooling or diarrhea, to death. Each ingredient is quantified by its percentage of the formula, dose form of product (liquid tincture, powder, gel caps, etc) recommended minimum and maximum dosing amounts, and the animal types for which each product is intended.
In the case of garlic, here is what I found: Over the course of 28 years approximately 350,000,000 doses of garlic have gone into the mouths of companion animals, including dogs, cats and horses, all with a wide variety of health conditions. Of this number, only 700+/- cases of minor adverse events have been reported (eg gas, vomiting) and only 8 cases of serious adverse events requiring veterinary care have been reported.
One of the greatest attributes of garlic as an herbal medicine and health supplement is that only a scant pinch is required to provide the antioxidant, liver supportive or immune enhancing activities that make garlic so valuable. Like most herbs, common sense equates directly to garlic’s safe use. Provided you follow the label directions of a reputable supplements provider and never feed more garlic than is recommended, toxicity should never be an issue. —GT