Ask a Vet: Midge Allergies

Q:  “I have three horses with sweet itch every summer and would like to know what Dr. Wilson would recommend to help control this issue.  Midge allergy I have been told.  3 of the 4 horses here and many other friends have the same issue. Break out on bellies but they rub their manes and tail docks too,” Val D., Texas.

A: Val, You are absolutely correct, sweet itch is an allergic reaction to Culicoides (Midges) and is the most likely cause of the skin condition you are describing.  Horses can also show similar skin lesions from allergies to other biting insects such as mosquitoes, black flies and horn flies. Midges are typically seen in the summer in northern climates but may be problematic year round in southern areas. Luckily there are several relatively easy management practices that can help reduce Midges. 

  • Drain all standing water.  Midges need standing water to propagate so getting rid of stagnant water will help break their reproductive cycle.
  • Midges are most active at night.  Keeping horses stabled at night and turning out during the day will cut down on your horses contact with them.
  • Have fans in your stalls.  Midges are small and have a difficult time flying in turbulent conditions.  Keeping a fan on your horse decrease the Midges ability to land on your horse. 
  • Use fly spray.  Look for products that contain the active ingredients pyrethrins or pyrethroids. 

Despite aggressive management practices some horses may still have skin reactions to these insect bites.  If this is the case, some medical treatment from your veterinarian may be needed.  The antihistamine hydroxyzine works well in many horses to help control these allergies.  A small percentage of horses may become so severe that they require treatment with corticosteroids to control the condition.   Furthermore, some horses many develop secondary skin infections from scratching these irritated areas.  If that is the case treatment with antibiotics or a medicated shampoo may be necessary.

Dr. Wilson is a native of Dripping Springs, Texas. She attended Texas A&M for her undergraduate studies in Biomedical Science and obtained her Doctor of Veterinary Medicine degree in the Spring of 2010. She has particular interests in lameness, internal medicine and surgery. Dr. Wilson joined Austin Equine as our first veterinary intern. She is member of the American Association of Equine Practitioners and the American Veterinary Medical Association. Dr. Wilson is thrilled to be living in the Austin area. Away from work, she is an avid rider and owns Malcolm, a twenty-one year old Thoroughbred.

If you have a question you would like to ASK A VET, please email with the subject: ‘ask a vet’

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