Horse Canada got help from Dr. Gillian Dobson, owner of Elm Creek Equine Veterinary Services, in Manitoba, to find out what causes horses to rub their tails and how to manage it before damage occurs.

Sneaky Pinworms

Pinworms, internal parasites scientifically known as Oxyuris equi, are the most common cause of tail rubbing, said Dr. Dobson. They usually measure about one to five centimetres, are whitish-grey, and live in the colon and large intestine, where, compared to other worms, they’re relatively harmless. They become bothersome when, surreptitiously at night, the females emerge from the rectum to lay their eggs around the anus and on the tailhead, returning through the rectum once they’re done. The goo they use to “glue” the eggs to the skin can lead to terrible itching.


Pinworms don’t always test in fecal egg counts, so Dr. Dobson said a tape test is the best diagnostic option. This involves sticking clear tape to the skin around the anus and looking for eggs under a microscope. Adult pinworms can also sometimes be found in manure.


A dose of an ivermectin-based dewormer followed by another dose three weeks later is the usual course of treatment, Dr. Dobson said. “In the meantime, I recommend washing the perineal area with a mild detergent and warm water, rinsing it really well and drying it in between.”


Horses become infected by ingesting pinworm eggs from their pasture, stable, bedding or food. To prevent the parasites from becoming a problem, develop an appropriate deworming regimen with your veterinarian.

Dirty Privates

A build-up of debris (smegma) in a male horse’s sheath or accumulated gunk (dirt, sweat, dry skin) around the female’s udder and vulva area can cause irritation, even infection. The horse resorts to rubbing their hind end and tail because they can’t scratch “down under.”


Other than tail rubbing, signs of trouble can include heat, swelling, a pus-like, foul-smelling discharge, redness and difficulty urinating. Your vet may take a skin swab and submit it for culture to determine if there’s an infection.


If there is an infection, your vet will likely prescribe medications such as anti-inflammatories and antibiotics. They may also suggest a thorough cleaning with warm water and mild soap. As some horses are sensitive to goings-on in their nether regions and might react with agitation or violence, it’s sometimes necessary for a vet to use sedation and do it themselves.


Many experts now suggest cleaning sheaths too often can do more harm than good by removing important natural protective oils and healthy bacteria, and even cause abrasions and sores. Nevertheless, some males may need an occasional tidy up in the region. Inspect a few times a year for an overabundance of smegma or a bean, a hardened ball at the tip of the urethra that can make urination difficult and uncomfortable. Same goes for the girls; check regularly for gunk at the vulva and especially between the teats, cleaning gently if necessary.

Itchy Dandruff

Dry, flaky skin on the dock of the tail is itchy business too. Primary seborrhea – or dandruff – is often caused by overuse of hair conditioners and detanglers, said Dr. Dobson. Other culprits include dirt and sweat build-up.


Separating the tail hairs, you’ll notice oily or dry dandruff-like flakes on the skin of the dock and stuck to hair strands.


To help with flaking and itching, Dr. Dobson said a good option is an old-timey concoction many horse owners still use – a combination of one cup of original (yellow) Listerine and half a cup of baby oil.


While thorough, regular grooming is a dandy place to start, Dr. Dobson also suggested tackling dandruff from the inside. “Feed a healthy source of fat as well as balanced vitamin and minerals to help the coat quality.” She prefers a feed-based coat product containing balanced omega 3 and omega 6 fatty acids.

Nasty No-see-ums

Sweet itch, or summer seasonal recurrent dermatitis, is a hypersensitivity to proteins in the saliva of the biting gnat or midge (Culicoides), better known as no-see-ums. The result is often extreme itchiness that can trigger horses to self-harm.


You might notice anything from a few broken hairs and somewhat of a rat’s tail appearance to skin that’s bald, raw and bleeding. Gnats also love biting between the hind legs toward the sheath or udder, prompting tail rubbing. In severe cases, sweet itch affects the mane, neck and chest. Skin scrapings can rule out infection.


Your vet could prescribe systemic steroids and antihistamines to relieve symptoms and/or topical corticosteroids. Anti-itch shampoos and even simply bathing with cold water may reduce irritation.


Regular grooming helps you keep an eye on any skin changes. Also consider stabling horses at dusk and dawn, both peak gnat-feeding periods. Use insect control in the barn such as time operated mists and fans. Insect repellents, flysheets and fly masks can thwart gnats when the horses are outside. Gnats require standing water to breed, so keep horses away from ponds, marshes or other breeding grounds.

These are the most common reasons a horse might start tail rubbing, but they’re not the only ones. Here’s a few more to consider if you are struggling to determine a cause:

  • Contact dermatitis – an irritation caused by directly touching something in the environment such feed, supplement, bedding or a grooming product. “Dirty flysheets and anything that covers the top of the tail area can irritate them as well,” said Dr. Dobson.
  • Lice and mite infestations.
  • Sunburn, mainly on lighter-coloured horses.
  • Sign that a mare is about to foal or, more seriously, indicative of colic and/or foaling complication. “If the foal is in the wrong position, sometimes the mare will really rub her tail and will sit on her butt and show a lot of discomfort.”
  • Habit, Dr. Dobson said she wouldn’t put tail rubbing down to a behavioural quirk unless all other causes have been ruled out. In which case, she might consider natural calming supplements to reduce anxiety and stress.

And, added Dr. Dobson, another reason you might find the hair disturbed has nothing to do with a tail issue at all. “Some horses will sit on their buckets and on their stall doors when they are lame behind. They’re not really scratching, but the hair is breaking because they’re leaning.”

While not an emergency, Dr. Dobson stressed you should discuss persistent tail rubbing with your vet. They will be able to properly diagnose the problem and provide effective treatment options, to make your horse comfortable, and his tail once again beautiful.

Tail Trauma

Itchiness is one thing, but the tail is also susceptible to some pretty serious trauma, said Dr. Dobson. “They can get enough of their hair caught in something that they can really badly injure their tail with an avulsion – pulling some of the tail off – or fracturing or dislocating the tiny little coccygeal bones in the tail.”

There could be unseen damage. Just recently, Dr. Dobson was doing artificial insemination on a mare with burrs creating a tangled matt in her tail. “It was a pet peeve more than anything, so I cut the matt out and underneath the tail bone was a bad, bad infection. The matt had pulled all the hair off the inside of the tail.”

She stressed, “Checking their tail is a really important part of taking care of their horses, for sure.”