It’s Itchy Scratchy Season: Why do horses itch?

Spring and summer are often difficult seasons for itchy horses and their owners. With warmer weather and longer days, there are more biting insects, mycotoxins and allergens present in the horse’s environment.

Higher humidity and proximity to bodies of standing water such as dams and puddles significantly increases horse exposure to the biting midges that cause chronic itching in horses commonly known as Queensland Itch, Sweet Itch or Summer Eczema.

Image: BugGuide.net

For most horses the itch cycle begins with an immune response to insect bites. Many itchy horses are hypersensitive to the saliva of midges from the species Culicoides. Insect bites tend to cause itchiness around the head, eyes, ears, mane, topline and tail.

For other horses the trigger can be feed or pasture mycotoxins or contact allergies caused by hypersensitivity to pollen, sawdust or other particles in the environment. These horses can develop hives or simply begin scratching.

Itch around the head, neck, chest, shoulders and underside of the belly can occur due to a sensitivity to a parasitic nematode, Onchocerca cervicalis. These nematodes are transmitted by Culicoides midges. The tiny larval form (microfilariae) live in the horse’s skin, mostly around the head, neck, shoulders, chest and underside of the belly. The adult worms become encysted in the nuchal ligament of the neck where they are resistant to deworming chemicals.

Pinworms and other intestinal parasites can cause itchy tails and hindquarters.

To successfully manage your itchy horse it is important to try to identify the trigger of your horse’s itch.