Garlic Supplement for Horses

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I Need Proof

I have met several people who are convinced that feeding a garlic supplement for horses is the key to natural fly control. To be sure I'm not the kind of person who believes that all truths have already been scientifically proven. I'm sure there are horse supplements out there, not currently holding science's seal of approval, that in time will prove to be good medicine. After all, willow bark was just an herbal remedy before scientific scrutiny proved what a great medicine aspirin is. However, when I'm confronted with information which seems to contradict a claim for a particular horse supplement, I want more than just someone's testimony that the stuff does what they say it does, and some reliable evidence that it isn't harmful.

My Observations

The state of Virginia seems to have one of every kind of nasty fly and biting insect. I've spent some time there watching the horses of people who have fed their horses garlic equine supplements to repel flies, and haven't seen any evidence that it worked. In fact, those horses were covered with flies, while other horses in the same pasture which had been sprayed with conventional fly spray remained fly free. OK, that wasn't a scientific study, but the difference between the fly count on the horses that had been fed garlic and the others was so remarkable many people commented on it even though they were unaware of the different methods of fly control used by the owners. And here's the kicker--there isn't any scientific study that shows garlic supplements for horses work.

Dr. Karen Hayes' articles on Garlic for Horses

There is evidence to suggest that garlic can be harmful to your horse, specifically that it causes hemolytic anemia ( anemia which results when red blood cells rupture). Please read this article written by equine veterinarian Dr. Karen Hayes about garlic supplement for horses. Here is a small portion of her most recent article in her blog:

Garlic contains a chemical compound called N-propyl disulfide (also known as “allicin”). It’s also present in domestic and wild onions, and in chives. And, it’s toxic for certain animals, particularly horses, cattle, and dogs. It damages their red blood cells, causing the cells to develop little pimples called Heinz bodies. This triggers the spleen to snatch the damaged cells out of the circulation and gobble them up—it’s one of the spleen’s jobs. The result is a declining red blood cell count, leading to a specific type of anemia called Heinz body anemia.
Please follow this link to read all of what Dr. Hayes says about garlic for horses in her blog . You will need to register (it's free) to read her blog.

Recent Research Showing the Effects of Garlic on Horses

A study published in the March 2005 issue of the American Journal of Veterinary Research, conducted by the Department of Animal and Poultry Science at the University of Guelph in Canada concluded:

Horses will voluntarily consume sufficient quantities of garlic to cause Heinz body anemia. The potential for garlic toxicosis exists when horses are chronically fed garlic.

In this study horses were fed freeze-dried garlic at a maximum amount of .25 grams per kilo of body weight for 71 days--less than three months. Researchers observed pathological changes in the blood when garlic was fed at an amount of .2 grams per kilo of body weight. For those of us who use pounds and ounces that's about 3.2 ounces of freeze-dried garlic a day for a 1000 pound horse. They continued to take blood samples from the horses for five weeks after garlic supplementation was discontinued. Although the results of the blood tests improved at the end of 5 weeks, at which point the study was concluded, aberrations in the blood were still visible five weeks after garlic supplementation was stopped. To read more about this paper or obtain a copy of it follow this link: garlic horses.

Recent Study on Garlic for Horses by the USFDA

A recent study was commissioned by the Center of Veterinary Medicine of the United States Food and Drug Administration to determine the safety of feeding garlic to horses. I've seen results of the study show up on the search engines listing the "safe dosage" amounts for horses, which suggests that there is a safe level of garlic which can be fed to horses, but the results of the study tell a different story.

The following is quoted from the summary of the committee's findings.

It was made clear to the committee that the report should address only safety and that utility or efficacy of animal dietary supplements, including garlic supplement was not part of the task.
So there was no intention to try to find out whether garlic supplements for horses accomplished anything at all, whatever the benefits claimed may be, just whether it was safe for horses to eat.

Under the heading Key Findings it says

A consistent finding from the study of lutein, evening primrose oil, and garlic was that there are insufficient safety data of a quality normally required for animal drugs and animal food additives.
Mind you the very people who sell garlic supplement for horses submitted information to the committee for consideration in this study, and still there was not enough information available to the committee to opine definitively on garlic's safety.

Follow this link to read a summary of the report.

Got Proof?

If anyone out there has knowledge of scientific studies which refute the studies sited by Dr. Hayes about garlic supplement for horses I would be very happy to hear from you.

Custom Horse Health Search Engine

To research further garlic supplement for horses or other horse health topics try this custom search engine for horse health information.

Have some fun with Horse-Report's horse names page.

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