EPM is a prevalent disease that affects many horses every year and it can be deadly. I know this all too well. We actually lost a horse to EPM recently and almost without warning.
I don’t want this to happen to someone else, so I did some research and wanted to share that information with my readers. When we had to put our sweet Daisy down, I was concerned about our other horses getting it. I just needed to more information to know how to prevent future infections.
The only thing the vet told me to do to prevent it was to feed them up off the ground, which is something we already did. We feed square bales and use a hay feeder that is off the ground. I also keep all feed sources in bins. But horses have their mouths to the ground frequently grazing, so these prevention methods didn’t seem like enough to me.
What is EPM?
Equine protozoal myeloencephalitis (EPM) is a disease of horses that affects the central nervous system. Equine obviously refers to the horse, protozoal refers to the type of organism that causes the disease and myeloencephalitis refers to that portion of the animal, which is damaged. “Myelo” refers to the spinal cord and “encephalitis” refers to an infection/inflammation of the brain. So, EPM is a disease of the brain and/or spinal cord of the horse, which is caused by a protozoan organism. (Reference www.aaep.org)
Where does EPM come from?
From my research, opossums are the most common carriers, but I also read that birds, armadillos, skunks, and even domestic cats can be hosts as well. I don’t know for sure that they can transmit the disease though.
Infected horses can’t spread it to other horses, but other horses can still get it from the same source that horse got it. Mainly opossum feces.
Studies show that some areas are more prevalent than others. Such as areas with moderate temperatures and higher humidity. The Mid-South and Southern states, for example, seem to be worse.
What to look for? Signs and Symptoms of EPM
If it’s caught early, you have a better chance at fighting this deadly disease. Because once inside the horse’s central nervous system, it multiplies quickly. While gait and balance are the main things to look for, it can be difficult to diagnose. Depending on what part of the spinal cord is affected will be where the signs show up. If it’s in the tail end, it will manifest more in the back legs, but above this level, it could affect the front legs. Either way, the vet told me she sees it affect the back legs more frequently.
Other symptoms could include drooping eyes or ears, difficulty swallowing (such as choking), or dropping feed.
Risk Factors & Ways to Boost Immunity
Once ingested, the parasite goes from the gut to the bloodstream, to the central nervous system, where it quickly begins multiplying. But usually a horse’s immune system will be triggered when they ingest the parasite and they then can fight it off before it reaches the central nervous system. Some ways to increase their immunity is to make sure your horse has a balanced diet and is receiving adequate nutrition.
Testing & Treatment
If your horse is showing clinical signs, then you might want to have them tested. Your vet will draw some blood and usually have results in a week. Many horses can come back positive though for exposure to EPM. If your vet agrees they think it is EPM, you could begin a treatment. It is usually a month long round of antiprotozoal (ponazuril). (reference link)
Reducing EPM Exposure in horses
The sporocysts seem to die in both freezing and hot weather so some seasonal prevention is an effective way to reduce exposure. Here are some ways to prevent opossums on your horse property:
A good farm dog to run critters off. Note: opossums are nocturnal, so it would need to be an outside dog, most likely.
You can also put out live traps to catch them and remove them from your property. It will probably be an ongoing battle, but what can you do?
Be mindful of what attracts opossums in the first place, such as:
- feed left out
- trash bins
- manure piles (even droppings in their pasture, looking for grain)
- fruit trees
- gardens
- bird feeders
- chicken pens
- dog or cat bowls (including water)
I hope you found this article helpful especially in ways to prevent EPM exposure to your horses. I know knowledge is power and when we know better, we do better. This disease can be devastating and I hope you never have to deal with it. Best of luck in keeping those pesky critters from your property!
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Unfortunately if you research more you will find that 70% of horses on the east coast carry this parasite. Some breeds of horses are more prone to it. Stress, travel etc increases the likelihood the disease will manifest. I lost my 32 yr old qh to it in august. Devastating.
I do have Great Pyrenees but wildlife is wildlife.
Good nutrition, reduce stress. I do not feed on the ground but unfortunately grass is on the ground.
Over feeding the other farm animals is a source of constant attraction to all the critters that carry ALL the things. We had friends that put out large amounts of cat food … in a bowl … left available around the clock. When we cared for their animals – we recognized the source of the complaints she had for “varmints”. We caught 6 raccoons in live traps that week – a whole family living on the excesses left by the kitties. Even food scraps thrown out are an attraction for possums and skunks!