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This is a discussion on EPM within the Horse Health forums, part of the Keeping and Caring for Horses category
  • Horses EpM does it ever go away
  • Horse exposed epm

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    12-17-2007, 03:06 PM

What is EPM exactly? Can it just affect a horse in a muscular way? If it goes away can it ever come back?
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    12-17-2007, 07:21 PM
EPM is a neurological disease caused by a protozoan parasite that, in a very small amount of the horses that are exposed to it, gets into the brain and/or spinal cord where it begins reproducing inside nerve cells and destroying them as it does so. It isn't a muscular disease but one where the nervous system is damaged and thus balance and movement are affected because the horse can't feel or control it's body normally.

Generally the first signs noticed are toe dragging on the hind feet, stumbling or tripping, odd gait, etc and progressing all the way to falling down.

EPM is diagnosed by ruling out all other neurological conditions which can have the same symptoms through testing, as well as performing tests on blood and cerebrospinal fluid to prove that the horse has been exposed to the parasite and whether or not the parasite has entered the central nervous system.

Horses can and do recover from EPM with appropriate treatment. The earlier it is diagnosed and treated the better. Rest and safe conditions during recovery are very very important to prevent the horse from hurting itself while it has issues with balance and movement.
    12-17-2007, 08:35 PM
I think Ryle mostly covered it but I do want to add a bit.
If treated early the horse can get better, live a productive lifestyle, and have no more signs. Horses can also have relapses or not respond to medication. I knew a horse who was diagnosed with EPM at 3 (he was only under saddle for a few months.. I rode him too =[) and had to be put to sleep because he didn't respond to the medicine.

The parasite that causes EPM occurs in possum poop that can be ingested in a field or worse, in the horse's feed bucket. That's why its pertinent to keep all feed storage areas locked (as possums will get into and eat horse grain) and call your vet if your horse has been off for more than a week or two.

The major problem EPM poses is that care can be expensive, especially if the horse will no longer lead a productive life (i.e. Doesn't respond to medication). Many people put their horses down at the diagnosis of EPM without even giving medication a shot (they feel its a waste of money in the end). Others try the medication for months at a time with no positive results (like the three year old I mentioned) and end up having to put the horse down. And still others can't afford the vet care or don't want to spend any additional money on an already burdensome animal and won't even have the horse diagnosed (and more or less let them wither away).

Yes there are plenty of success stories and I feel the medication, diagnosis, treatment are well worth the cost- even if my horse doesn't fully recover- but it's not an easy disease to overcome..
    12-17-2007, 11:27 PM
A few clarifications:

Originally Posted by drop_your_reins
EPM never goes away, the horse has it for life. If treated early the horse can get better, live a productive lifestyle, and have no more signs, but the treatment is a lifetime one.
Originally Posted by drop_your_reins
Horses can also have relapses even on medication. I knew a horse who was diagnosed with EPM at 3 (he was only under saddle for a few months.. I rode him too =[) and had to be put to sleep because he didn't respond to the medicine.
This is incorrect. The disease is curable and treatment is not a lifetime thing. Some horses will recover 100% and others will always have some lingering neurological deficit, but this is not because the disease is still ongoing but because damage to the central nervous system can be permanent.

Unfortunately, EPM is also a very over-diagnosed problem--especially in the last 15 years when just about every horse that came into a vet clinic with neurological deficits was labelled as "probably EPM" and treated without so much as a blood test to prove that the horse had even been exposed to the parasites. Many horses are labelled as having EPM that have some other condition and this is the most common reason for a horse "not responding to the medication". A thorough and logical progression to getting a diagnosis with neurological conditions is very important because many problems can present with the same symptoms and without appropriate diagnostic testing you cannot be sure what you are dealing with.

Originally Posted by drop_your_reins
The virus that causes EPM occurs in possum poop that can be ingested in a field or worse, in the horse's feed bucket.).
Yes, possum feces is the most common route of transmission, but it's not a virus--it's a single celled organism.

Originally Posted by drop_your_reins
The major problem EPM poses is that care can be expensive, especially if the horse will no longer lead a productive life.
Diagnosis and treatment is expensive, however EPM doesn't mean that a horse will never again be useful. I know several people who have treated their horses for EPM and now ride and even compete cross-country on them.[/b]
    12-18-2007, 12:15 AM
My mistake, I thought EPM was treatable (halting the bacteria at whatever stage it is) but not curable.
The horse I referred to had several blood tests to confirm EPM and was on medication for I think six-eight months (I'm not sure I was 12 at the time so my impression of things wouldn't be the same as it would be if it happened today) and showed no signs of improvement. Our vets are very thorough and some of the most popular vets in a very horse rich part of the state. I should have checked my facts before I posted, so I'll edit my post so no one gets the wrong impression. And I did misuse the word virus, I know it is a parasite, but I was in a rush when typing my response, again my mistake.. I am certainly a far cry from a vetirinarian. Also, I was mostly replying because you didn't exactly put EPM in a negative light and it can be a very negative thing.

While there are success stories, it all relies on the financial capabilities of the owner and frankly whether or not the owner cares enough to get the horse tested.

I know a mare who had symptoms similar to EPM. Clumsiness, wasting away of topline muscle, etc. Unfortunately (or perhaps fortunately in her case, as her owners were not the type to get her tested or even pay for treatment whatever the diagnosis) she came down with severe colic and had to be put to sleep. The reality is that some people don't care about their horses enough to pay for expensive treatment, or they simply can't afford it.

So I apologize again, the last thing I would want to do is spread incorrect information. My intention in posting was to relay that many horses do not recover well and others have no chance to recover because their owners are unwilling to pay for treatment.
    12-18-2007, 11:10 AM
Thanks for all the information. I was looking at a horse and the owner told me that the horse was treated for EPM about 2 years ago, but she said "not due to the usual symptoms, just because of stiffness and lack of muscle gain for the amount of work they were doing with the horse. They go on to say that he was treated with Marquis, (whatever that is) and seems now perfectly fine and has no symptoms. Can you make any sense of this? Is this maybe a misdiagnosis?
    12-18-2007, 11:47 AM
If you are interested in this horse, I would have the owner send your vet a copy of the medical records to review and also have your vet perform a thorough physical examination that includes working the horse for a while and then doing a neurological examination. This is because horses with permanent neurological deficits can look absolutely normal due to learning to compensate, but then when they are sick or tired the neurological deficits become more noticeable.

There is a good possibility that the horse was misdiagnosed because without neurological symptoms it's highly unlikely that EPM is present. It is all too common that horses are diagnosed and treated without even doing blood tests and it's pretty well impossible to differentiate between neurological diseases without testing. But even those that have a positive blood test are most likely not diseased as blood tests can only show exposure to the parasite and less than 1% of the horses that get exposed to the parasite will actually develop the disease. Having your vet assess the horse before you decide whether or not to purchase him is the best way to go.
    12-18-2007, 02:08 PM
Thanks, I was really wondering about that. I haven't had a horse for a few years but I'll find a vet and have that done first.
    12-18-2007, 06:38 PM
Really interesting topic. I had never heard of it before. Thanks for the input everyone, I learned something :) Glad my dogs love to kill possums and I keep my feed in metal cans with heavy lids in a locked barn.
    12-18-2007, 09:59 PM
Yeah I never thought to keep lids on the grain really good until now!

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