Equine Protozoal Myeloencephalitis (EPM) is a life-threatening neurological disease that directly affects the horse’s nervous system—brain and spinal cord. If not diagnosed and treated aggressively at an earlier stage, the chances of survival of the horse become quite bleak. While we cannot really say how long can a horse live with EPM, the severity of the infection and speed of treatment can help one estimate how much life is left in the steed.
In this article, you will get to know how the horses get infected with EPM? How long can a horse survive after getting infected by Equine Protozoal Myeloencephalitis (EPM)? And what are preventive measures you can take to prevent your horses from getting EPM in the first place?
What is EPM In Horses?
Equine Protozoal Myeloencephalitis (EPM) is one of the most debilitating and progressive neurological equine illnesses in which the central nervous system of the horse is attacked by protozoan parasites, mostly Sarcocystis neurona and less commonly by Neospora hughesi. Depending on the severity of the disease, the horse might be unable to stand or walk properly, and sometimes, it becomes difficult for the horse to even brig his head down for grazing.
Causes of EPM In Horses
Equine Protozoal Myeloencephalitis is caused by the protozoan parasite Sarcocystis neurona, a microbe commonly found in the opossum. Horses develop this neurological disease when they are exposed to infected opossum feces. When a horse drinks/eats water or food contaminated by these disease-causing parasites, they get infected by EPM.
However, this disease does not spread from one horse to another horse like a viral disease. The protozoa are unfurled by the host, the opossum. Opossum gets the organisms from armadillos, harbor seals, sea otters, cats, skunks, raccoons, etc. The feces of opossum contain the infective stage of these organisms known as sporocysts. When horses interact with infective sporocysts while eating or grazing, they develop EPM.
These infective sporocysts pass from the intestinal tract to the bloodstream and eventually cross the blood/brain barrier. The central nervous system gets attacked by these sporocysts. The disease spreads slowly, but if it goes undetected and untreated, its effects could be devastating and will cause significant neurological damage and might even lead to the death of the suffering horse.
Symptoms of EPM In Horses
The symptoms of Equine Protozoal infection are quite similar to other neurological diseases, making it difficult to diagnose. The symptoms of EPM may depend on the severity as well as the location of lesions that develop in the brain, brain stem, or spinal cord. Some of the common symptoms discovered by the American Association of Equine Practitioners (AAEP) are:
- Muscle Atrophy
- Abnormal sweating, difficulty in swallowing,
- Dropping eyes, lips, or ears( paralysis of eyes, facial or mouth muscles)
- Ataxia, i.e., incoordination that typically happens when a horse moves up or down and when the head is in an elevated position
- Stiff or stilted movements
- Tilting of the head with poor balance
- Loss of sensation ability along the neck, face, or body
Here is a video of a horse named Fiedler, who was diagnosed with EPM in May 2016, successfully recovered, and was doing great by August 2016. However, unfortunately, a year later, he relapsed and lost his ability to chew hay or grass due to permanent facial muscle atrophy. Now he is doing great but is only able to eat soaked grain, beet pulp, and quid hay if fed.
How Long Can a Horse Live With EPM?
It is difficult and almost impossible to say exactly how much time a horse can survive with EPM. Different horses may respond differently to the EPM treatment, that’s why it is not easy to figure out the exact survival period of a horse. Still, if this disease is diagnosed at earlier stages, the recovery chances of a horse are better, and they can survive longer. So, the moment you get a hint that your horse is showing EPM symptoms, immediately get it diagnosed and start aggressive treatment to increase the chances of recovery.
15 to 25% of the horses recover completely from EPM. Research suggests that around 60-70% of the horses show improvement by undergoing treatment. However, it depends on the stage when treatment is initiated; early treatment shows the best results. The duration of the first four weeks exhibits the greatest amount of improvement.
Despite the treatment, almost 80% of horses remain positive on spinal taps. These horses might not even depict symptoms of illness. Relapses often occur within two years in 10-20% of horses.
Factors Determining How Long Can a Horse Live With EPM?
EPM is a fatal neurological disease, and a lot of horses end up losing their lives, whereas only a few horses infected with EPM manage to survive. Various factors that help us to predict how long a horse can survive with EPM are discussed below.
· The Stage of Diagnosis
The diagnosis stage is an important factor for predicting how much time a horse has to live. If EPM is diagnosed at earlier stages, there are more chances that the horse will recover and vice versa.
· The Quality of Treatment
If EPM is diagnosed at an earlier stage and the horse is put on an aggressive and quality treatment, then the survival chances are more than those who receive less aggressive treatment. That said, you should keep in mind that different horses respond differently to treatment, and about 10% to 20% of horses relapse within 2 years. So do your best and then hope for the best.
· Severity of Infection
If the disease has fully taken control of your horse, then it might not be wrong to say that survival chances are almost non-existent. So, the severity of infection is an important factor that helps us predict how long a horse can live.
Also, if the vet has declared the disease incurable, it means that there are almost nil chances of recovery of the horse. The horse might not be able to live even for a few months.
In case EPM has progressed to incurable levels, instead of thinking about how long the horse would survive, responsible horse owners start thinking about euthanasia. A horse not able to graze, walk, or even stand properly is no life, so the only viable and humane thing to do is to put an end to the suffering of one’s steed. This way, horse owners can at least take solace in the fact that their friend is no more in pain.
How long a horse will survive also varies from horse to horse. Some horses may even live a year, while others may not even survive for a month. Some even relapse a year or two after their recovery.
Is EPM In Horses Fatal?
The EPM attack may or may not be fatal depending on different circumstances. If the infection is severe, then there are more chances that the horse might not be able to live for longer. The severity of the infection is dependent on the following factors.
- The number of organisms a horse has ingested can be used to examine how severe the infection is. If a horse has more exposure to contaminated grass or feed, it is more likely to have a far more severe infection than those whose exposure was limited to those conditions.
- If the horse is not treated on a timely basis, the risk is more, as the parasites may have reproduced and caused more damage.
- Stress level also helps to determine the severity of the infection. A horse who is under stress and gets infected with EPM is prone to more damage than others.
- The severity of infection also depends on the location of the damage. EPM infection may occur at any point in the horse nervous system, i.e., in the brain, spinal cord, or brainstem.
What Can You Do To Prevent EPM In Horses?
EPM can be prevented to a large extent by taking necessary steps such as proper storage of horse feed, careful disposal of animal carcasses, and a few other measures. Try to control the population of opossum around your barn to avoid the EPM in horses. Another preventive technique is to keep the grains in covered bins. Metal containers having tight-fitting lids can keep the grains safe from parasites. It is advisable to lock the feed room and hay storage areas so that no opossum can get in and infect the feed and bales of hay. Keep the water tanks filled with freshwater.
So, keeping your horse healthy, feeding him with a proper diet, regular veterinary visits, and opossum/rodent-free habitat can help significantly reduce the risks of EPM contraction in your horses.
Treatment options for EPM
Three FDA-approved products are used for treating Equine Protozoal Myeloencephalitis. These are:
- Pyrimethamine/Sulfadiazine ( also known as Rebalance)
- Diclazuril (Protazil)
- Ponazuril (Marquis)
It depends on the treatment response of horses to determine how long to stay on drugs. It is usually a 28-day course. However, most horses suffering from EPM are treated for a period of six to eight weeks and even longer if clinical improvement is seen.
Generally, mild infection can be cured within 28-30 days. Moderately infected horses may even need more than 120 days to recover and function normally.
Potential Side Effects of Treatment
The drugs used for EPM treatment can affect the iron levels of your horses. The vet keeps on checking the iron, platelets, and blood cell count throughout the EPM treatment. The use of Antiprotozoal drugs may affect the fertility of stallions. Similarly, unborn offspring and pregnant mares can also be at risk. So, stay in close touch with your vet while your horse is under treatment. You should report any changes in symptoms or behaviors to your vet.