Should I Feed My Horse Garlic to Repel Insects?

Last Updated on February 25, 2022 by Allison Price

I’m always on the lookout for natural ways to repel flies from my barn. I heard that feeding garlic to horses can prevent them from biting. Is this possible? Can you feed garlic to horses?

A:Garlic has many benefits, including its ability to repel insects, respiratory health, antibacterial and antimicrobial properties and potential to improve the quality of your skin. Garlic is believed to repel insects by creating an odor in the sweat when it’s eaten.

Organic sulfur compounds are abundant in garlic and other onion members. In organic chemistry, an organic compound is one that contains significant amounts of carbon. A thiosulfate is one of many sulfur compounds found in garlic. It has antibacterial and antiparasitic qualities that can be found in allicin, a pungent oily liquid found in garlic.

Despite allicin’s antibacterial and parasitic properties, data is scarce on its effectiveness as a fly repellent. I don’t know of any studies done with horses. One study that tested garlic oil applied topically at a 1 percent dilution showed a 97% repellent effect.

Garlic and Garlic Consumption: Dangerous Potential

Only a few studies have examined the possible side effects of giving horses garlic. There are several potential toxic substances in garlic and other alliums, which are plants belonging to the onion family. The principal one is N-propyl diulfide. This compound alters enzyme glucose-6-phosphate deshydrogenase (a protein responsible in transporting oxygen in blood cells). Heinz bodies are formed when hemoglobin is damaged and precipitates on the red blood cells’ surface. Anemia is caused by a reduced number of red blood cells in circulation. This can be caused by the liver and spleen working together to remove damaged red cells. This type of anemia is also known as Heinz body.

Horse Garlic to Repel Insects

Horses can get Heinz body anemia from eating more than 0.4g per kilogram of freeze-dried garlic. This is equivalent to giving a horse weighing 500 kilos (1,100 pound) 200 or more grams of freeze dried garlic per day. That’s just half a pound. This amount could be easily consumed by horses that eat wild garlic grown in pastures, but it is unlikely that they would receive this amount for their own benefit.

Researchers found that a 32 mg (mg), per kilogram of bodyweight, of garlic over an 83-day period led to a decrease in hemoglobin and red cell count. This means that a 500-kilogram horse could be fed as little as 16 grams (about a half ounce) of garlic per kilogram of body weight.

Many people who eat garlic report no adverse effects. However, clinical signs may not be apparent and could vary depending on how often and how long they are given.

According to the National Research Council, more data is needed to assess the potential benefits and risks of feeding garlic to horses. However, the National Research Council says that horses should not be fed 15 mg per kg of body weight daily (or 7.5g) of dried garlic powder under normal circumstances.

Take-Home Message

Although consuming 7.5 grams of garlic daily might not cause side effects, it is worth asking if that much would be effective as an insect repellent. Diluted garlic oil applied topically may be more effective.

Allison Price
Allison Price

I’m Allison, born and raised in San Diego California, the earliest memory I have with horses was at my grandfather’s farm. I used to sit at the stable as a kid and hang out with my Papa while he was training the horses. When I was invited to watch a horse riding competition, I got so fascinated with riding!