Why does my horse have crusty bumps after fly bites?

Read time: 3 minutes

Overview

Crusty bumps after fly bites are often just the skin’s reaction to being bitten, especially in summer when flies are active. In many horses, the bumps are small, itchy, and dry up into scabs or crusts, but there can be several possible causes, including a stronger insect-bite reaction or irritation from rubbing.

Things To Check

1. Notice when the bumps appear, such as after turnout, at dawn or dusk, or after riding and grooming.

2. Look closely for redness, heat, swelling, broken skin, scabs, discharge, or signs the area is getting rubbed.

3. Check whether your horse seems itchy, stamps, swishes the tail, or tries to rub the area on fences, doors, or tack.

4. See if the bumps are limited to exposed areas such as the face, belly, legs, ears, or dock, which can help you spot a fly-related pattern.

5. Compare one area with another to see if the bumps are scattered, grouped, or spreading.

6. Think about any recent changes in turnout, bedding, grooming products, fly season conditions, or skin care routines.

7. Check whether your horse has had a similar reaction before, as some horses seem more sensitive to bites than others.

Common Causes

The most common cause is a local reaction to fly bites. The skin can become raised, itchy, and then form crusty bumps as it settles.

Some horses react more strongly than others, so the bumps may look more dramatic than the bite itself would suggest.

Rubbing or scratching can also make the skin crust over, even if the original bite was mild.

Less commonly, a bump may be irritated by mud, sweat, flies around a small skin scrape, or another skin sensitivity that happens to appear at the same time.

What To Do

Keep an eye on the area for a few days and note whether the bumps are improving, staying the same, or spreading.

Try to reduce further irritation by keeping the skin as clean and dry as practical and discouraging rubbing where you can.

If your horse is outdoors a lot, review your fly-season routine and adjust turnout timing, rugs, shelter, or stable management as needed.

If the bumps are being opened up by scratching or rubbing, it helps to keep the area clean and avoid adding products unless they are suitable for that part of the body.

If the reaction keeps coming back, gets worse, or seems to bother your horse a lot, it’s sensible to speak to your vet for advice.

Products That May Help

Fly-season skin care often works best when it’s part of a steady routine rather than a one-off fix. A practical collection for summer management may help support that day-to-day approach.

Horse Fly Sprays & Summer Care

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