EPM in Horses and Other Medical Worries

Posted by Allie Layos

A lot can go wrong with your horses, and their health and safety depends on your knowledge.

Horses are touchy, sensitive creatures, and countless diseases and injuries can plague them. No horse owner is an expert on every equine medical issue, but it is important to know some of the most common ones.

Here are a few to keep on your radar.


Horse with colic lay down and sleep outside

Colic, a broad term for abdominal pain in the horse, is far more common than horse owners would like. It is a terrifying word because, despite considerable research, it still remains a bit of a mystery, and can be fatal if not treated properly.

There are many different types of colic, as it can be caused by many things: parasites, ulcers, tumors, or twisting of the small intestines or colon. Most colics end up being either gas and spasmodic colics or impactions.

Some horses are more stoic than others, so the signs of colic can vary from horse to horse, but the most common signs are restlessness, pawing, continually laying down and rising, rolling, groaning, excessive yawning, lethargy, sweating, loss of appetite, or a horse who is continually looking at its abdomen.

The horse may have an elevated temperature, heart rate, and respiratory rate as well as increased capillary refill time and a change in its gut sounds.

If you suspect that you horse has colic it is important to call your vet as soon as possible. Your horse may need to receive fluids, a nasogastric tube, laxatives like mineral oil, and may even need surgery.


horse, horse's neck, the horse in the summer, horse chestnut

Equine protozoal myeloencephalitis (EPM) is a disease that affects the central nervous system in horses. Though opossums have long been considered the definitive host, the apicomplexan parasite Sarcocystis neurona, which causes the disease, can be found in many animals including raccoons, cats, skunks, and armadillos.

Horses contract the disease from contaminated food or water, but they are a dead-end host, and cannot pass the disease on to other horses.

General weakness, ataxia, lameness and muscle atrophy are some of the main signs of EPM. The disease is treatable, but treatment is expensive and may not reverse prior damage to the nervous system. Treatment involves antiprotozoal drugs, anti-inflammatory drugs to reduce further damage to the nervous system, and antioxidants to help restore the nervous tissue.

Navicular Syndrome

woman cleans the horse's hooves with a brush

Navicular is caused by inflammation or degeneration of the navicular bone and surrounding tissue in the horse's hoof. The navicular is a bone that is positioned behind the coffin bone and under the small pastern bone.

There is no single cause of navicular syndrome, but there are many theories and contributing factors, and conformation is one of the most common. Horses with small feet, upright pasterns and a significant downhill build are more prone to navicular, as well as horses with a high weight-to-foot size. For these reasons the American Quarter Horse is the breed most often associated with this syndrome. Poor shoeing and work on steep hills, galloping, and jumping can also contribute to navicular.

Cole Henderson/Horse Journals

By the time the horse becomes consistently lame, the degenerative changes to the navicular bone are already advanced, so treatment consists of managing the horse's condition and pain, as well as slowing the degeneration. This is usually accomplished with corrective shoeing, a less intense work schedule, and medications.

As a last resort, some owners choose a surgical procedure known as palmar digital neurectomy where the palmar digital nerves are severed, cutting off the horse's sensation to the back of the foot.


Washing of feet and hooves horse closeupLaminitis is a painful inflammatory condition of the laminae (or tissues) in the horse's hoof that bond the hoof wall to the coffin bone. It can result in a condition known as founder, the coffin bone tearing away from the hoof wall and rotating or sinking into the sole of the hoof.

Many things can cause laminitis, including excessive intake of grass or grain, infection, obesity, response to certain drugs, and even other diseases such as Cushing's disease.

A horse with laminitis will often shift its weight from foot to foot, or stand with its front legs stretched forward, shifting weight to its back legs. Its hooves may be warm or hot to the touch, and the soles will be painful when pressure is applied. As with any horse in pain or distress, laminitis cases will show an increased pulse and respiratory rate.

Laminitis should be treated as an emergency, and you should always call your vet. Frog supports and medications to control blood pressure may help acute cases, while more mild, chronic cases may require the combined efforts of both your vet and farrier. For all laminitis cases, stall rest is vital. Deep, non-edible bedding can often do as much good as frog supports.

There are many other ailments that could plague your horse, but an understanding of these four is a good start. There is no better feeling than catching a problem early; it may save your horse's life.

Has your horse ever suffered from any of these syndromes? Tell us your story in the comments below!

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EPM in Horses and Other Medical Worries