Treating Sweet Itch

Sweet itch is a skin disease that has troubled horses and horse owners for ages. Here's how to treat it. By Dr. Matthew Mackay-Smith for EQUUS magazine.

A skin disease caused by allergy to the bites of tiny Culicoides midges, sweet itch has bedeviled horses and confounded horse owners for many years. When we asked EQUUS magazine readers to share their favorite methods for foiling the gnats that cause sweet itch, we received many responses. Here are some of the best suggestions:

  • Use fly sheets designed or modified to extend at least halfway down the horse’s tail, thereby covering areas that gnats especially like to attack.
  • Add cider vinegar the horse’s feed.
  • Apply small amounts of Avon’s Skin So Soft bath oil to the most vulnerable areas.
  • Apply menthol products, such as Vick’s VapoRub or a cheaper generic version, to susceptible areas.
  • Feed the horse about 2 tablespoons of garlic powder two times a day to make his sweat smell garlicky and repel the flies.
  • Braid Bounce or another brand of scented dryer sheets into the horse’s mane and tail, and rub them over the horse.

Soothing Sweet Itch Sores A reader also offers this recipe:

Combine the following ingredients and apply the mixture to sweet itch sores twice daily.

  • 8 oz. of Gold Bond Medicated Body Lotion (Extra Strength, in green bottle)
  • 4 oz. Aveeno Anti-Itch Concentrated Lotion
  • 4 oz. Benadryl Itch-Stopping Gel
  • 4 oz. Avon Skin So Soft (increase up to 8 oz. if the gnats are bad).

Related Reading: Investigating an Itch Question: I own an 11-year-old Thoroughbred gelding. I boarded him at a local farm for six years and during the last two, he developed severe itching and skin rashes. About 10 of the 40 horses on that property had the same problem. The barn is located in an urban area in a valley on a stream with a wetland “swampy” area about a quarter mile away. The barn is well run and the stalls are cleaned daily. The barn has been in this location for about 60 years, but the skin problems have only developed in the last 7. Feed and bedding can’t be the source, because other area barns use them with no problem. The itching and rash seem to be triggered by the heat.

My veterinarian performed allergy testing on my horse in the spring of 1998, and found only a sensitivity to fleas. We tried a series of desensitization shots and the barn manager even had a professional exterminator spray the barn for fleas, to no avail. Bird mites were discovered on some horses that autumn. The horses were treated and barn was bird-proofed.

I left that barn and my horse’s skin cleared up. I returned in the winter and stayed until the following spring with no trouble. This December, however, when we returned, his reaction in less than 24 hours was so severe we had to leave again.

Other boarders have had the same experience–the itching stops when they leave. What could this be?

Name withheld by request

Answer: Sweet itch (gnat allergy) and bird mites best fit the pattern you have described. I would, however, lean towards the sweet itch.

Bird mites rarely cause bumps or a rash and last year’s protracted autumn in the Eastern United States gave months of extra life to gnats. In our area of Virginia, they were still active into late December. Besides keeping your horse indoors at dawn and dusk–prime feeding times–there is little you can do to combat these insects.

Because in already-sensitized horses it takes just a few gnat bites to cause a full-blown reaction that lasts for weeks, managing sweet itch becomes challenging with the passing seasons. Gnats travel as far as a half mile away from their swampy breeding grounds and prefer to feed on the skin around the tail head and crest. The itchy reaction can take two to three days to develop so gnats may not be present when horses are itching. (In contrast, bird mites can be seen on close inspection of the hair coat.)

Management of sweet itch focuses on symptomatic treatment and various deterrent strategies. Corticosteroid creams or injections reduce the inflammation, and a colleague of mine says a daily heaping teaspoon of aspirin powder helps some sweet-itch sufferers “miraculously,” so you can give that a try. As for repellents, sprays aren’t effective against gnats. My favorite deterrent is baby oil, liberally applied to the root of the mane and tail. The gnats can’t seem to get a grip on it to feed. Mix in some scarlet oil for more efficacy. Your horse will get kind of greasy, but you may prefer that to the itch. If anyone has a surefire repellent for gnats or treatment for the allergy, please share it.

Dr. Matthew Mackay-Smith is the medical editor at EQUUS magazine.

This article first appeared in the June 2000 issue of EQUUS.




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