Should I Feed My Horse Garlic to Repel Insects?

Our equine nutritionist takes a closer look at garlic’s potential to fight off flies and biting insects.

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Should I Feed My Horse Garlic to Repel Insects?
While many people feed garlic and report no ill effects, the clinical signs might not be obvious and depending on the dose, frequency, and duration of the dose given there could be low-grade deleterious effects. | Photo: iStock

Q: I am always looking for natural ways to repel flies in my barn and I have heard that feeding garlic can stop flies from bothering horses. Does this work and is it safe to feed garlic to horses?

A: Garlic is touted for several beneficial functions, including respiratory health (it is supposed to alter the physical properties of mucus), antibacterial, and antimicrobial properties, and its supposed ability to repel insects. The thinking is that feeding garlic creates an odor in sweat that helps repel flies.

Garlic and other members of the onion family are rich sources of organic sulfur compounds (in organic chemistry, “organic” means a compound contains a significant amount of carbon). One of the many sulfur compounds present in garlic is a thiosulfate, which has been associated with antibacterial and antiparasitic properties found in allicin (a pungent, oily liquid in garlic)

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Written by:

Clair Thunes, PhD, is an equine nutritionist who owns Clarity Equine Nutrition, based in Gilbert, Arizona. She works as a consultant with owners/trainers and veterinarians across the United States and globally to take the guesswork out of feeding horses and provides services to select companies. As a nutritionist she works with all equids, from WEG competitors to Miniature donkeys and everything in between. Born in England, she earned her undergraduate degree at Edinburgh University, in Scotland, and her master’s and doctorate in nutrition at the University of California, Davis. Growing up, she competed in a wide array of disciplines and was an active member of the U.K. Pony Club. Today, she serves as the district commissioner for the Salt River Pony Club.

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