Insect bite hypersensitivity or IBH, also known as sweet itch, makes the summer months miserable for many horses, ponies, and donkeys. Research is continuing into understanding why only some horses are affected by IBH and designing vaccines that might be used to block the immune response in affected animals. This research has been given greater impetus because of the role biting insects play in the spread of Bluetongue Disease and their potential as carriers of African Horse Sickness.
Symptoms of IBH or sweet itch include hair loss, thickening of skin, flaky dandruff along with attempts to relieve the itch by rubbing against fences, posts, and corners of barns and stalls.
Allergic reaction of horses to the saliva of biting midges of the Culcoides family, is a seasonal, recurrent phenomena. Scientists at Bristol University have now identified the offending proteins present in midge saliva and are working to find the most effective way of administering these in a course of immunotherapy,
One possibility ot presenting IBH is to immunize foals with these proteins so that their immune systems develop tolerance. Adult horses might be exposed to small, but increasing amounts of the proteins through repeated injections or the incorporation of these proteins in foods that could work by oral medication. This works should not be confused with on-going trials of a so-called sweet itch vaccine.
So far, avoiding midge bites is the mainstay of preventing IBH with efforts being centered on reducing midge numbers, making horses less attractive to them and stopping them from biting horses with protective gear and careful timing of turn-out time in pastures and other areas where midges are prevalent.