If you have never had a horse that suffered from Sweet Itch, consider yourself lucky. According to an article posted on www.thehorse.com, as many as 60% of horses in Queensland, Australia, are affected; more than 21% of horses in Israel; 26% of horses on the northwest coast of North America; and nearly 5% of horses in Japan.

Sweet Itch is an allergic reaction to the saliva from the bite of midges — also called no-see-ums or gnats. The midges travel down the long hairs of the forelock, mane and tail to reach the skin and bite.

Horses that are allergic to the bites have a hypersensitivity reaction — an acute allergic reaction — which sets off a cycle of itching and scratching. In extreme cases the horses suffer so severely that they drop to the ground to roll and scratch themselves or destroy fencing by rubbing on it. Most horses simply end up with sores and hair loss, mostly along their mane and tail and spend a lot of time scratching, swishing their tails and biting at themselves.

Preventative Measures

• No see ‘ums congregate in wet areas like water troughs and ponds. Try to keep tanks clean or add a filter to keep the water moving.
• Keep your horse inside during from about 4pm to 8am when midges are at their worst
• Put bug screens on stable windows
• Hang insect-repellent strips in the stable and braid fly repellent tags into your horse’s mane and tail.
• Put fans in the barn, as gnats cannot fly against a strong air current
• Use an effective insect repellent daily
• Keep your horse in a fly sheet with a neck guard and a fly mask.
• Consider adding garlic to your horse’s feed (but be careful because too much garlic can cause anemia)

Treatment

According to a study conducted by the University of Guelph Equine Research Center (ERC) feeding flaxseed (linseed) can relieve the symptoms of sweet-itch.

Flaxseed has long been recognized as a superior vegetable source of omega-3 fatty acids to treat many atopic (allergies likely to be hereditary) skin diseases in dogs. But while it is commonly fed to horses to improve the hair coat, the exact effect of these omega-3 fatty acids on the equine dermis (skin) is unknown.

In the ERC’s double-blind study, six Icelandic horses with a history of sweet-itch (confirmed by a skin test with Culicoides extract) were fed ground flaxseed, or an equivalent amount of bran meal as a control, for 42 days. On Days 0, 21, and 42, the horses were injected with Culicoides extract, saline (as a negative control), and histamine (as a positive control, guaranteed to trigger a skin reaction), and the resulting reactions were assessed over a period of 18 hours. Samples of skin, blood, and hair were also taken to provide a fatty acid profile.

Horses on the flax seed supplement showed significantly smaller skin test reactions to Culicoides serum after 42 days, indicating a less severe allergic response. Researcher Wendy Pearson O’Neill, MSc, also noted a reduction in the long-chain saturated fatty acids in the analyzed hair, which she says is an indication of changes in secretions from the skin. “By altering the fatty acids in the skin secretions, it’s possible that certain populations of dermal microflora were affected, changing their ability to metabolize compounds such as histidine and trans-urocanic acid, which are involved in immune function,” she explained. “This would reduce the overall immune response to Culicoides injection.”

Feeding flax seed is simple — studies have shown that you can feed it whole. I personally feed a cup and a half per day. You can see my previous post on it — Flax Seed: How and why to feed it to find out the other health benefits to feeding flax.

Sweet Itch Information & Resources

Cure closer for sweet itch in horses

Treating sweet itch gnat allergy

A guide to sweet itch in horses by Global Herbs