The Itchy Horse Can Drive You Crazy

One of the most infuriating, frustrating issues is a horse with skin problems. Thankfully, most horses don’t have sensitive skin or allergies. But for the few unlucky ones that do, owners can be brought to tears, since the problem never really seems to go away.

Midline dermatitis, aka sweet itch, is caused by tiny bugs called “no-see-ums.”

Itchiness (also called “pruritus”) can occur from a variety of causes and can start at any time during a horse’s life. We’ll take you through some of the common causes, and explain what you can do to mitigate the problem. See prime suspects for causing itching.

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HELP! MY HORSE ITCHED HIS TAIL OUT! We’ve all seen it, heard about it, or experienced it: a horse scratching out his mane or tail. Even though these are the most common presenting complaints when it comes to itchy skin, several other behaviors and hair-loss patterns are also reported.

Commonly, horses will experience hair loss (aka alopecia) on their underbelly and ventral midline. Geldings may have firm, incredibly itchy sheaths with dry skin. Some horses will itch out hair on their face or on their haunches.

In rare circumstances, mares can present with a mammary gland infection (mastitis) which is caused when they “dog sit” on the ground and rub their bellies in the dirt. Dirt gets into their teat, which in turn causes an infection. But even mares with just dirty udders can become master tail-itchers. Keeping your horse’s sheath or udder clean is step one in these cases. 

Some horses will lose hair in patches all over their body while others will repeatedly break out in hives. Regardless, these horses are usually very sensitive to the touch. Some of them itch so much it almost hurts. They may even want you to itch them to a point but then become stand-offish if you are over-zealous.

Although we don’t commonly think of it, skin is a vital organ, as are the liver, kidneys, heart and lungs. If any of these became inflamed, we’d definitely sit up and take notice. Yet with skin, some of us more or less give up when we see lackluster results despite our strong efforts. Well, don’t give up!


Horses that itch constantly can have serious physiologic consequences.? Obviously the skin itself can be damaged by constant scratching. Horses will often rub so vigorously that they will macerate their skin. These cuts and scrapes are painful and can become infected. After many repeated insults, skin can actually become permanently thickened and scaly. This process is called “lichenification” and is irreversible in some cases.

Beyond the skin itself, pruritus can result in other physiologic problems. In some horses, itching is so intense that the horse can’t sleep. After prolonged stretches (usually weeks to months) with no significant sleep, it starts to show.

Horses will become fatigued and can actually “zone out” and nearly fall over before they catch themselves. This behavior is not benign, since we know that horses must sleep in order to maintain proper brain function. Some experts postulate that the relentless itching irritates horses to the point where they develop gastric ulcers. So clearly, horses that itch terribly can truly be suffering.

COMMON CAUSES. There are several possibilities when it comes to causes of pruritus in horses. But by far and away, biting insects are the most common cause. Owners often report that since they don’t see any insects they doubt this as a cause. The problem is that most of these bugs are difficult to see with the naked eye.

Hives require immediate veterinary attention (pollen may be the cause).

Not all horses are sensitive to insect bites, just like not all dogs are sensitive to flea bites. But if your horse is one of the unlucky that is allergic to the saliva of a certain insect, life can be difficult.

These horses will itch on any object to try to find relief, even to the point of breaking boards and bending no-climb wire because they sit on the fence while rubbing their tails. Horses may even kick at their own underbellies in an attempt to stop the tingling.

Horses have little sense of self-preservation when they itch, and as a result many times skin can become deeply abraded and in some instances, will have foreign objects like wood splinters embedded.

If you’re able to identify what type of insect is causing your horse to have skin reactions, you may increase your chances of controlling the problem. However, they may be sensitive to several types of biting insects, making it more difficult. 

INSECTS AND BARN MANAGEMENT. Use fly masks with ears. If you have trouble keeping your horse’s mask on in pasture because of pesky pasture-pals, cut the Velcro closure to match the hook portion exactly so there’s nothing for the other horses to grab and pull. Many horses think this is a fine game.

Be sure you fit the mask?s closure snugly (but not choking tight) with just enough give in the elastic for comfort. This will decrease the chance of your horse being able to rub it off. If your routinely turn your horse out in a halter (because of barn rules or another necessity), only use a breakaway halter and place that over the fly mask for added security.

Horses can wear a mask at night if they are in a safe, enclosed, secure and familiar setting. Nose and ear flaps protect from sunburn and go a long way to relieving irritation by insects. While the lighter mesh fly? masks are easier for horses to see through, they’re not as durable and a rubbing horse will destroy them in no time flat.

Fly sheets with tail flaps, neck sleeves and, especially, wide belly bands increase protection over the common areas where flies bite.

Some fly sheets are impregnated with pyrethrins to repel insects; it’s not perfect, but it helps. Fly sheets can stay on the horse 24/7 (since some insects are still active even in the late evening), but always take it off and replace it daily to inspect the horse’s coat for irritations. Most fly sheets can be washed on the wash rack with a hose and some laundry detergent.

Fans in stabling areas can help inhibit flies from landing on and biting your horse in the stall.

Biting and chewing lice can infest your horse, laying eggs everywhere.

We love fly parasites! They?re the tiny wasps that live in the manure pile and feed on fly larvae and can substantially reduce your fly population. Getting your neighbors to use them, too, is a big plus since you need a wide radius around your property to be depopulated in order to see the maximum benefit. These wasps do not sting or bite people, so don’t worry! 

Of course, you know to manage stagnant/standing water by dumping and cleaning troughs periodically or if troughs are too large, use mosquito fish or mosquito rings. Always dump out standing water from buckets, tires, feed bins where it accumulates. See environmental allergies.


As if insects weren’t enough to make our horses? skin crawl, some horses can have environmental allergies. Horses can get instant, severe contact hypersensitivity reactions when various agents from plants come into contact with their sensitive skin.

For most plant-related hypersensitivities, removing either the plant from the horse’s environment or the horse from the plant’s environment is best. Of course, if you live in New York and your horse is allergic to Maple trees, or if you are in California and Oak trees don’t jive, well, you’ve got quite a problem.

BOTTOM LINE. The fact is, controlling allergic reactions is no picnic. it’s critical that you know exactly what you’re dealing with.

If you try one of our suggestions and you see no improvement in your horse’s skin within three days, contact your veterinarian. If you see worsening, call your vet immediately. The worse and larger the area becomes and the longer it goes uncontrolled, the more time it will take for you to get it under control and the longer your horse will suffer needlessly. See the best treatment choices.

Article by Contributing Veterinary Editor Grant Miller, DVM.

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