Tail rubbing can be a frustrating problem. Sometimes the cause of your horse’s itching isn’t obvious, making the topicals you apply of little use. Sometimes the scratching itself results in irritation and more itching, becoming the secondary cause that keeps your unhappy horse rubbing away.

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Here, we’ll identify many of the potential causes of tail rubbing, plus give you advice for helping it to stop. Work with your veterinarian as necessary to identify the cause of your horse’s itching—and relieve it.

Bugs. Culicoides gnats (also called midges, sand flies, or “no-see-ums”) are the most common cause of tail rubbing. These tiny blood-feeders are active at dawn and dusk through the spring and summer in many areas, and some horses are extremely sensitive to their bites. The resulting allergic reaction, which affects multiple parts of the body, is known as sweet itch. What to do: If possible, keep your horse stabled during key feeding times at dawn and dusk. (The insects don’t like to enter buildings; fans can provide an added deterrent.) Non-irritating bug-repellent sprays and gnat-proof sheets also help if your horse must be out. Your vet may prescribe corticosteroids and/or antihistamines to help with itching until any open sores heal. (Note: Other bugs—such as ticks, mites, and lice—can also cause tail-rubbing, but are less common; follow your vet’s advice for eradicating these.)

Pinworms. Adult pinworms crawl out of a horse’s rectum to lay their eggs around the anus, causing intense itching. The eggs are difficult to see with the naked eye. Though pinworms are often suspected first, they’re now a less-common cause of tail rubbing thanks to deworming agents. (Most, such as ivermectin and pyrantel, are effective against pinworms.) What to do: Thoroughly deworm all horses on the premises with a product that’s at least 90-percent effective against pinworms. Inspect and clean rear ends as needed, plus decontaminate waterers, feeders, and tail-rubbing spots to eliminate as many stray eggs as possible.

[READ: Horse Parasite Control]

Dirt, sweat, dry skin. Tail rubbing can be prompted by dirty, sweaty skin on the dock, under the tail, in/around the sheath or udder, or in the crevice between the hind legs. Harsh cleaning or fly-repellent products that dry the skin in these delicate areas can also cause irritation that leads to rubbing. Sunburn on the dock can cause itching, as well. What to do: Keep all of your horse’s private areas clean and well-rinsed. Minimize irritants such as harsh detergents or shampoos; favor moisturizing, healing ingredients such as aloe vera. Apply soothing salves, ointments, or creams to irritated areas to promote healing. Also provide UV protection as needed for vulnerable skin.

Other allergies. Apart from Culicoides reactions, in rarer cases tail rubbing can be the result of an allergic response to something in your horse’s environment (such as contact dermatitis from, say, his bedding) or to a type of feed (alfalfa, wheat, oats, bran, or various additives can be allergens). What to do: This is a tough one. Remove suspected allergens from your horse’s diet or environment to the extent possible. For contact dermatitis, your vet may prescribe corticosteroids and/or antihistamines to keep your horse comfortable until signs subside. If you suspect a food allergy, an equine nutritionist’s advice may also be helpful.

Habit. When the primary cause of tail rubbing persists over time, the behavior can become habitual. This is especially true for horses that are confined and lack grazing and/or equine companionship. What to do: Keep your horse clean, comfortable, and as irritant-free as possible to give him a chance to “forget” the behavior over time. Providing for his social needs—ideally grazing with pasture-mates during non-buggy times—will help to keep him happily occupied.