Managing Insect Bite Hypersensitivity in Horses

Key Takeaways

• Insect bite hypersensitivity–often triggered by Culicoides midges–affects up to 60% of horses in some regions, typically beginning around age 3-4 and worsening with age; while not curable, symptoms can be managed.
• Reducing exposure is key: keep sensitive horses stalled during peak midge activity (dawn and dusk), use premise sprays, and run fans since midges struggle to fly against airflow.
• Regular use of topical insect repellents and steroid-based sprays like EquiShield IBH can help reduce itching and irritation in affected horses.
• Physical barriers such as fly masks, sheets, and boots provide added protection, while allergy-support supplements like Equishield SA can help support immune response during warm months.
• Good pen management–including keeping areas dry, removing manure, and preventing standing water–helps limit midge breeding and reduces exposure.

Have you noticed your horse becoming more sensitive to insect bites or developing allergies during the warmer months? In some parts of the world, insect bite hypersensitivity affects up to 60% of horses, often triggered by the saliva of biting midges (Culicoides spp.). Most horses show signs around three to four years of age, with symptoms worsening as they get older. Some horses have a much stronger reaction to the midge saliva than others. 

Although there is no curative treatment for this condition, Dr. Laura Meier, Technical Service Veterinarian at Valley Vet Supply, offers several options that can help provide relief for your horse.

Minimize Exposure to Culicoides midges

These insects are most active at dawn and dusk. Spray your horse’s environment with premise spray during these times and keep horses with sensitivities out of pastures. Using fans in stalls and pens can also help, as biting midges can’t fly exceptionally far or against the wind effectively.

Apply Topical Insecticide Repellents

Spray your horse regularly with insect repellents, be sure to follow the instructions on the label for amounts and durations.

Use Sprays with Topical Steroids

These can help alleviate itching in sensitive areas. Examples include EquiShield IBH Insect Bite Hypersensitivity Spray or Salve for Horses.

Protect Your Horse with Physical Barriers

Use fly masks, sheets, and boots to protect your horse’s skin from insect exposure.

Consider Allergy Supplements

During warmer months, allergy supplements like Equishield SA (Skin and Allergy Powder) can support your horse’s immune system.

Maintain Proper Pen Husbandry

Keep pens dry and clean and remove manure promptly. Biting midges thrive in warmer temperatures and damp areas, so preventing standing water in pens can help reduce their presence. Pay attention when filling water buckets and troughs.

Whether for horse, livestock or pet, Valley Vet Supply is your one-stop shop for trusted care. Explore more of our horse fly control category at ValleyVet.com