How Long Can a Horse Live With EPM? 11 Important Symptoms

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Last Updated on March 31, 2023

If your horse has been diagnosed with EPM, you might have a lot of questions. How long can a horse live with EPM is a common concern, with many horse owners worrying about the costs of treating a horse with EPM as well. Let’s find out everything you need to know about EPM in horses, including how long can a horse live with EPM.

What is EPM in Horses?

EPM is a serious neurological disease in horses. The full name of this condition is Equine Protozoal Myeloencephalitis, and it is caused by a protozoal parasite named Sarcocystis neurona.

It is estimated that over half of all horses in the US have been exposed to this organism, but it is not spread from horse to horse. The protozoa are transmitted by its definitive host, the opossum. The organism can also be transmitted to raccoons, skunks, armadillos, cats, and possibly even sea otters and harbor seals.

When an opossum is infected with Sarcocystis neurona it then sheds infectious spores in its feces. These are then ingested by the horse when they consume contaminated feed or water, or graze on contaminated grassland. 

This organism then has devastating effects on the horse, as it can migrate from the gastrointestinal system into the bloodstream. Here EPM can cross the blood/brain barrier, enabling them to attach to the central nervous system of the horse.

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How is EPM in Horses Diagnosed?

The problem with EPM is that it can be very difficult to diagnose, as the symptoms are very similar to many other equine disorders. The symptoms also vary widely from horse to horse and can be very subtle or extremely severe.

Your veterinarian will carry out a full neurological examination on your horse, in an attempt to reach a diagnosis. The following symptoms may all occur in a horse with EPM, and it is normal for one side of the body to show more effects than the other.

Symptoms of EPM

  • Ataxia, incoordination, and weakness
  • Abnormal or stiff gait, or lameness
  • Worsening of symptoms when going up or downhill, or when the head is elevated
  • Weakening and wastage of the muscles, particularly on the top line and hindquarters
  • Drooping of the eyelids, ears, or lips
  • Difficulty when swallowing food or water
  • Collapse or seizures
  • Patchy sweating
  • Head tilt
  • Poor balance
  • Reduced sensation to touch on the face, neck, or body

If your veterinarian suspects that your horse has EPM, they may carry out tests on both blood and cerebrospinal fluid. This will show whether the horse has been exposed to the parasite that causes EPM, but will not confirm if it has the clinical disease.

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How Long Can A Horse Live With EPM?

EPM Horse Behavior Changes

One of the reasons that EPM can be tricky to diagnose is that it can take a long time for behavior changes and symptoms to occur. In some horses, it can take months or even years for symptoms to begin showing. In other cases, the behavior changes and other symptoms may appear within a couple of weeks to months.

For some horses, the symptoms of EPM may subtle and appear gradually, whereas for other horses the symptoms may be more prominent. While behavioral changes do not appear in all horses with EPM, they are more common in severe cases.

When EPM causes behavior changes in horses, it is often because the disease has affected the barn. Horses that develop behavior changes in EPM also often exhibit facial paralysis, seizures, difficulty swallowing, and head tilt. However, this only happens in rare cases with horses with EPM.

Supplements for EPM Horses

If you suspect your horse might have contracted EPM, it is important to contact your vet. Your vet will be able to diagnose your horse and if your horse has EPM, they will be able to provide proper treatment.

If your horse is recovering from EPM, there are certain supplements you can feed that will aid in the recovery process. Vitamin E supplements are one of the best options for horses recovering from EPM as it supports muscle and nervous tissue as well as improve the immune system.

In addition to Vitamin E, a low NSC ration balancer and Omega 3 Fatty Acids can be beneficial for horses recovering from EPM. It is always best to ask your vet for advice before starting your horse on a new supplement.

Is EPM in Horses Curable?

EPM is considered a treatable disease as long as it is caught early enough. When treatment is received on a timely basis, up to 60-70% of horses will improve greatly and 15-25% can make a full recovery.

The key factor to treating EPM is catching it as soon as symptoms appear. If EPM goes undiagnosed and untreated, it can lead to devastating and lasting neurological deficits or even death.

EPM in Horses

How to Prevent EPM in Horses

While it can be tricky to prevent possums from venturing into your pastures, you can take measures to keep them out of your barn.

Be sure to keep your feed room clean and tidy. Securely store all grain, supplements, and concentrates that could be enticing to possums.

In addition, seal off your barn and shelters to help prevent possums from entering them. Immediately remove any wildlife carcasses you may find on your property. Also, try to reduce your horse’s stress level as stressed horses are more prone to catch EPM.

Be sure to also keep any hay or bedding clean in your barn. If any feed or bedding has been contaminated with wildlife feces, be sure to dispose of it right away and clean your barn. Also, be sure to regularly clean water troughs and buckets to minimize the chances of contaminated water from wildlife.

How is EPM in Horses Treated?

The key to success when treating EPM in horses is to begin treatment as soon as possible. Any delay in treatment will adversely affect the chances of the horse making a full recovery.

Your veterinarian will prescribe a course of anti-protozoal medication to treat EPM, as well as anti-inflammatory drugs to protect the horse from the effects of parasite die-off. Anti-inflammatories also help to reduce the clinical signs of EPM.

It is also common to give horses with EPM a supplement containing vitamin E, as this supports the healing of the nervous system.

A full course of treatment for EPM normally takes at least one month and up to six months in some cases. The treatment can be expensive, and many horse owners find they cannot afford to treat their horses if they are diagnosed with EPM. Regular blood tests can be taken to assess the response to treatment for EPM in horses.

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How Long Can a Horse Live With EPM?

The chances of a horse making a full recovery from EPM are greatly increased when a prompt diagnosis is made. If a course of treatment is started straight away, most horses will make a full recovery.

However, around 10-20% of horses will relapse within two years, and some horses never recover at all. This is more likely to occur when treatment is delayed, and the neurological problems become too severe.

If a horse is not treated for EPM, it will develop life-long neurological problems that can be devastating. This will normally result in the euthanasia of the horse.

How Long Can A Horse Live With EPM?

Summary – How Long Can a Horse Live With EPM?

So, as we have learned, how long can a horse live with EPM depends on how quickly treatment is started. A prompt diagnosis and a full course of treatment will give the horse the best chance of making a full recovery. If left untreated, EPM causes significant and life-long neurological problems.

We’d love to hear your thoughts about how long can a horse live with EPM! Have you ever owned a horse that was diagnosed with EPM? Or maybe you’ve got questions about the best treatments for horses with EPM? Leave a comment below and we’ll get back to you!


What Are The First Signs Of EPM In Horses?

The first signs of EPM in horses can be very subtle, and will vary from horse to horse. At first, you may just notice that your horse seems a bit off-color, without any specific symptoms. Over time, more overt symptoms will start to develop, such as neurological issues, collapse, and seizures.

Is EPM Painful For Horses?

Many of the neurological symptoms suffered by horses with EPM are not painful in themselves, but your horse will be feeling some discomfort. A common problem in horses with EPM is pain around the top of the head, due to swelling of the spinal cord.

Can A Horse Have EPM For Years?

Most horses with EPM make a full recovery, as long as treatment is initiated promptly. However, some horses will retain some neurological symptoms, even after a prolonged course of treatment. These may remain for the rest of the horse's life, even if the clinical condition has been resolved.

How Long Should A Horse Be Treated For EPM?

The minimum length of time for a course of treatment for EPM is one month. Depending on the type of drug used and the response to treatment, this can be extended for up to six months. Your veterinarian will take regular blood tests to assess the response to treatment.

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