Insect bite hypersensitivity (IBH) is a common seasonal allergic skin condition in horses. It occurs in horses worldwide and is the result of an immediate, type I hypersensitivity reaction to the saliva of biting flies (Simulium and Stomoxys species) and midges (Culicoides spp).
IBH affects between 3 to 60% of horses worldwide, of all age groups. Although the condition has been found to worsen with age. IBH is a multi-factorial disorder influenced by both genetic and environmental factors. Certain breeds of horses have a higher likelihood of developing IBH than others; Icelandic, Shetland ponies, Thoroughbreds, Quarter horses, and German Shires have a genetic predisposition to suffering from IBH.
Horses with IBH develop severe itchiness and discomfort; they are often seen scratching and biting themselves, sometimes using objects they find in the pasture such as shrubs and small trees. The constant scratching often causes skin irritation which leads to hair loss, crusts, papules, and lichenification of the skin. The parts of the horse's body most affected include the mane and tail, ears, dorsal midline and rarely ventral thorax/abdomen.
IBH tends to occur seasonally in horses, with clinical signs coinciding with months where flying insects are most abundant---between April to October. Horses tend to demonstrate increased signs of discomfort during the times of the day that insects are most likely to feed, which is usually the morning and evening hours.
keep horse stabled at desk and dawn; Modify horse's turnout schedule so that they are not out in the pasture during dusk or daybreak, as this is when sand flies undergo peak activity. Utilize insect repellents, fly traps, better manure management, remove stagnant water, use of fans in stalls
Provide protective barrier
fly sheets, fly masks, fly boots
As a supplement in diet
added as a dietary supplement
Apply long lasting insect repellents, especially in the evening and early morning
Use a fly sheet, fly mask with ear protection, and fly leg guards when horse is turned out
Utilize cooling fans when the horse is inside the stall since biting insects are not great flyers
Routinely clean or treat water troughs
Spread fly predators
Apply mineral oil to horse prior to turnout along ventral midline