Learn More About Sweet Itch

Two Types Of Sensitivity When It Comes To Sweet Itch

No one thinks Sweet Itch is appealing. The seasonal skin condition can be managed, treated and prevented. Both you and the horse will be happier.

Biting midges, known as gnats, or no-see-ums’ often trigger an allergic reaction when a horse is bitten. The reaction is not caused by the bite, the insects’ saliva is the culprit. Just as people may develop a rash after exposure to specific allergens, while others don’t, some horses are abnormally sensitive to midge saliva.


Small Insect, Huge Troublemaker

Midges, primarily Culicoides, are small insects unable to cover large distances. They feed at night and live near standing water. Sweet itch, in many regions, is seasonal. But in some areas they’re active year-round. In colder climates, there may be just one species, and in warmer climates, like Florida, there may be over 20 different species. The more species present in an area, the more generalized the distribution of lesions.


Affected Areas

  • Main and tail
  • Ventral midline (the center of the belly)
  • Legs
  • Face and ears
  • Or some combination


Conditions and Allergies

Horses which are sensitive to Culicoides saliva tend to develop two types. Type 1 is a fast, almost immediate, reaction and these horses often present with hives.

Type 4 comes with a delayed reaction and signs of sweet itch appear within 24-48 hours following the bite. The types of allergies are determined by multiple chemicals in the horse’s body and many animals have both.



Treatment options for Type 1 include antihistamines. Type 1 horses with numerous allergies have options and an equine pharmacist can formulate custom-made vaccines which desensitize with immunotherapy.


Bird Mites

When bird mites are found in a barn, it can be easy to confuse the bumps and rash with sweet itch. However, bird mites rarely cause the symptoms. In some Mid-Atlantic states, such as parts of Virginia, bird mites can remain active into late December. Other than keeping the horse indoors at dawn and dusk — which happen to be prime feeding times — there is little which can be done to control bird mites.

As already-sensitized horses need just a few gnat bites to trigger a full-blown reaction which can last weeks, staying on top of sweet itch grows increasingly challenging through the years. The itching may take two or three days to develop, meaning gnats may not be around when the horse is itching.

Bird mites can be seen on the horse’s coat.


Unusual Remedies

Managing sweet itch takes a focus on treating the symptoms while using a variety of deterrent strategies. Success depends on this two-prong strategy.

Corticosteroid cream can reduce inflammation. Some owners have successfully used a heaping teaspoon of aspirin power daily to relieve the suffering.

Sprays are not an effective deterrence against gnats, but liberally applying baby oil to the root of the mane and tail keeps gnats from getting a grip as they feed.