Why is my horse getting small crusty bumps after being bitten by flies? | arlo.® Atlas
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Overview
Small crusty bumps after fly bites are often a mild skin reaction to irritation, but they can have a few different causes. In many horses, they settle once the fly pressure drops and the skin is kept clean and watched closely.
Things To Check
1. Check when the bumps appear, such as after turnout, in the evening, or after being near marshy or fly-heavy areas.
2. Look closely for redness, heat, swelling, scabs, broken skin, discharge or obvious soreness.
3. See whether your horse is rubbing, stamping, tail swishing or generally trying to get away from flies.
4. Check whether the bumps are only in exposed areas, such as the face, belly, sheath, legs or under the mane and tail.
5. Make sure the skin is not dirty, damp or covered in sweat, as this can make irritation look worse.
6. Notice whether other horses in the same field have similar signs, which can help you judge fly pressure in the environment.
Common Causes
The most common reason is a local reaction to fly bites. Some horses get small raised bumps or crusts where the skin has reacted to the bite itself.
Fly bite irritation can also become more obvious if the horse is sensitive, itchy or repeatedly rubbed by insects or tack.
Less commonly, the bumps may be part of a broader skin issue such as mild dermatitis, sweat irritation or a secondary skin infection if the area has been scratched or broken.
What To Do
Keep a simple eye on the area for a few days and note whether the bumps are improving, spreading or becoming more inflamed.
Gently remove dirt, sweat and loose debris from the coat, especially after turnout or exercise, and avoid rough scrubbing over the affected skin.
Try to reduce fly exposure where you can, especially at the times of day when flies are worst. Stable management, turnout timing and keeping the surrounding area cleaner can all help support comfort.
If the skin is being rubbed, pick the area over carefully and avoid any grooming that seems to make it more sore.
If the bumps keep returning, spread, or seem linked to ongoing itching rather than a one-off bite reaction, it’s sensible to get a vet’s opinion.
Related Questions
Could these crusty bumps be sweet itch?
How can I tell if a fly bite reaction is getting infected?
What’s the best way to check my horse for fly irritation after turnout?
Atlas is here to support owners with practical, easy-to-understand guidance. It is not a substitute for professional veterinary advice. If you're concerned about your animal's health, symptoms worsen, or something doesn't feel right, contact your vet.