EPM
May 7, 2009
Equine protozoal myeloencephalitis is a heartbreaking disease.
EPM left a hand sized dip in this successful barrel racer's face.
By Becky Newell in America’s Horse
Equine protozoal myeloencephalitis is a neurological disease caused by a tiny parasite. Opossums carry the parasite, and horses contract the disease by eating feed or drinking water contaminated by opossum feces.
EPM is characterized by the three A’s: Asymmetrical ataxia (incoordination) with or without muscle atrophy (degeneration).
Signs of EPM
- Incoordination (ataxia): stiff, stilted movements (spasticity); abnormal gait or lameness.
- Incoordination and weakness that worsens when going up or down slopes or when the head is elevated.
- Muscle atrophy, most noticeable along the topline or in the large muscles of the hindquarters, but sometimes involving the muscles of the face or front limbs.
Since approximately 50 percent of U.S. horses have been exposed to the organism responsible for EPM, it is extremely important to know the signs of infection. Early detection and treatment are key to recovery. Download The Racing Journal’s FREE EPM report to start protecting your horse.
- Paralysis of muscles of the eyes, face or front limbs.
- Difficulty swallowing.
- Seizures or collapse.
- Abnormal sweating.
- Loss of sensation along the face, neck or body.
- Head tilt with poor balance; horse may assume a splay-footed stance or lean against stall walls for support.
Preventing EPM
- Keep feed rooms and feed containers closed and sealed.
- Use feeders that minimize spillage and are difficult for wild animals to get into.
- Clean up any dropped grain immediately to discourage birds and other scavengers.
- Feed heat-treated cereal grains and extruded feeds.
- Keep water tanks clean and filled with clean, fresh water.
- Maximize your horse’s health and fitness through proper nutrition, regular exercise and routine deworming and immunizations.
- Schedule regular appointments with your equine veterinarian.
To reduce your horse’s risk of contracting this disease, you must take preventative measures. Download The Racing Journal’s FREE EPM report for more important tips to prevent exposure to the organism that causes equine protozoal myeloencephalitis.
Treating EPM
In July 2001, the U.S. Food and Drug Administration approved Marquis, an oral paste that was the first medication developed specifically for the treatment of EPM in the United States. Marquis is manufactured by AQHA Corporate Partner Bayer Animal Health and is an FDA-approved EPM treatment.
Marquis is given to a horse once a day for 28 days. Although most horses respond favorably, drug treatment is not a guarantee for 100 percent improvement. The parasite behind EPM causes damage to the brain and/or spinal cord, so even though it may be out of the horse’s body, some of the damage done may be permanent.
It’s also possible that horses can experience relapses of the disease and even be reinfected. Unless the horse’s environment is drastically changed, there will be continued exposure to the parasite. The sooner you treat a horse that’s showing signs of EPM, the better the chances of a positive outcome.
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23 Comments on “EPM”
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May 15th, 2009 at 6:38 pm
Hi just thought I would like to say, that I have a 9 year old quarter horse that had EPM last October, and was treated with Marquis and another drug after that. He has made a full recovery. I have just started riding him. I’ve owned him for two years now, and he has never rode so good. The vet figures he had the parasite when I bought him. We moved last spring, and the stress of the move likely brought it on. The more information that can put published the better. A lot of horse people have never heard of the disease.
Tammy Clayton, Ontario
October 31st, 2009 at 8:24 pm
Tammy, I’d heard of it, but I didn’t know much about it until
my 5 year old gelding was diagnosed(tentatively) with it last week.
We’re still waiting for the the blood work to come back from Kentucky.
I’m praying it’s not EPM, but he has the clinical signs. Drags his hind end, toes dragging and part of the hoof wall (outer skin)
is peeling off. So far no signs in the face or neck. I should get results back this week.
November 8th, 2009 at 11:17 am
I have a 9 year old gelding that I used for barrel racing, and he started showing lameness early this year, so the vet injected his hocks and stifles, may 22, when he wasnt fully recovered , I took him back jule 8, when it was suggested a epm blood test . the test was neg, and only 1.20 on exposure, so we turned him out.At that time no active disease was present so I did,t go thru the expense of medication. It was suggested but not strongly recommended.
3rd week of Oct , another vet gave him dex for inflammation in his stifles, and within 5 days he has paralisis on his right side of his face,lip and ear hanging. and eye drooping. I took him off the dex, and his lameness is gone, the eye looks better but the ear and lip, and a little cloudiness in right eye is present. Is it too late for him to get marquis? Is the damage done? He’s eating well and drinking on the left side, and is interested in the mares again, he’s always thought he had a “loaded gun!”
My insurance co, Markel, says I was negligent in NOT treating him back in late July,and if he declines won’t cover the loss… and at this time he’s actually feeling good. Any ideas on whats happening and a course of action?
January 7th, 2010 at 10:18 am
My 7 year old Paint horse, that I own for 1 year now, was diagnosed with EPM 4 weeks ago. Right after I found out, I ordered the Treatment Marquis and started to give it to him right away, now we have one week left of the treatment. On the first week, I saw immediate change with him, he stopped dragging his rear feet and toes, and was eating much better. In the second week he started to run with normal gait, finally. I’am very positive he will do a good recovery. We caught him in stage 1 of the desease. It was pretty hard to figure it out that he had that, because he showed intermittent symptoms. but in my training, I knew something was wrong because he was not improving at all in his work. He had a lot of difficulty with his leads, and it was like he did not know where his hind legs where, and I was asking pretty easy stuff for him to do. Anyway, it was a pretty weird feeling on the horse, it was like he did not have much balance. I tryed to do barrels with him, when I did not know he had the EPM, When I was letting him go at his own speed it was fine, when I started to ask more pressure, everything fell apart. I have not restarted the training, since i’am waiting for the treatment to be over and to give him time to recover afterthat. He his now at rest and goes outside with an old mare, to make sure he has less stress as possible.
January 20th, 2010 at 10:27 pm
In the summer of 2008, my horse, Steele was positive for EPM. We treated him with Navigator for 4 weeks, but he still showed neurologic signs of EPM. We then put him on Marquis for 4 weeks. He made great improvement, and by the end of his dosage of Marquis he seemed to have made great recovery with minimal deficits. The past month (January 2010) we started noticing Steele seemed “off” in his hind end. He is a very sweet dispositioned horse. He started laying his ears back when we put the saddle on him! Then he started stumbling. We took xrays thinking Navicular. I walked out of the tack room to see him standing on the cross-ties with his butt wedged up against a stall door. He was pressing his weight against it so hard I thought he would break it down! The old signs of EPM returned to my mind!!! My vet was still at the barn, so I had her do a blood test for it (they now can test for EPM through a simple blood test – I am told you don’t need the spinal tap like I had to do the first time). The labs compared his reports with his old EPM reports. My vet reviewed the results with the Doctor that treated Steele at our Equine Center; and sure enough, he has EPM again! To my surprise, upon further research today, I have found that 25% of horses infected with EPM can relapse, usually within 18 months. I will be treating Steele again with another round of Marquis. He is only 5 years old; he is beautiful both in disposition and in his looks; and most importantly he is my BABY! We bought him when he was 2 and only halter broke. With LOTS of help, we broke him after his first bout of EPM when he was almost 4. I love him so much, if anyone has more information they can offer to help Steele with a full recovery of this dibilitating disease, I’m open for suggestions!
January 25th, 2010 at 1:45 pm
I have a horse with EPM as well. A very nice barrel horse. He started his treatment and its now been 4 months and we have been getting him legged back up for a couple of weeks. He is doing great. We did a different approach and went with the silverlining herbs. Good luck to us all
April 1st, 2010 at 6:02 am
[...] on the stage of disease and the prognosis, as well as a means to monitor the progression of the disease and its response to [...]
May 12th, 2010 at 7:13 am
I am awaiting the titer test for EPM, as well. My mare, purchased last year, exhibited a few minor symptoms (tripping, uncoordinated movement), but we took a wait and see approach, as I had plans for training. She didn’t improve, and her gaits grew more “off” and it appears there is some muscle atrophy in the hindquarters. I am not going to do a spinal tap, due to our location, costs, and risks. I have not decided how to treat her. The meds are cost-prohibitive and pose their own problems. But, she is only 6 years old and just a wonderful animal!!! I absolutely love her, and I am really worried about the best way to approach this. My husband would rather NOT go through the expensive and length treatment, considering I only paid $900 for the horse. I understand where he’s coming from… she’s not an expensive show horse. But, she’s MY horse! At what point do you consider alternative therapy vs. drugs? I am considering starting her with Vitamin E, MSM, and maybe some alternatives. Try it for a while… build up her immune system and neuro paythways. THEN, if no improvement, start Marquis. Any opinions?
June 13th, 2010 at 1:45 pm
Me, again. Test came back positive. Can’t afford Marquis at $1,200 a month, so I went with something less expensive. Also, ordered SmartPaks (10,000 units of vitamin E, selenium, other supportive supplements, and the EPM herbs from Meadowherbs.com.
We start treat now! Oh, boy, not too excited to do this. Still have mixed emotions about the drugs. Would rather do the herbs and supplements and see how it goes, but vet feels strongly that we need to use the drugs and not wait any longer.
June 16th, 2010 at 7:34 pm
I would love to talk to someone via phone as I have too much that I want to say in writing. Can someone who has had success with EPM medication please call me at 423-240-8371. I just started Navigator this evening, but I am scared. My 28 yo mare went down in her stall at 5:00 am this morning. She has not been diagnosed officially by 3 vets. I believe she has EPM by the fact that she has 10 of 15 symptoms relating to her gross motor ability. One vet felt she has DJD in her neck that was shown on x-ray. She would favor one hind limb, then weeks later the other, then would look symmetrical(equal) for up to 2 weeks. She got up herself and did fair when in the arena later this morning. Now back in her stall she is leaning badly. She looks terrific for her age. She is a thoroughbred. She weighs 1,000lbs and is eating well. Am i doing the wrong thing? Someone please call me anytime. I live in Tn. and am on central time. My home number is 423-837-5505. Cell is 423-240-8371. Thank you for sharing. Miriam J. Herstik
June 21st, 2010 at 3:05 pm
do the marquis. it’s the only thing I’ve seen that works consistently. My gelding began tripping severely and started having some training issues that refused any logical definition. He also demonstrated clinical signs when he failed the neurological test. We did not blood test him or tap him–just started the marquis, after which he initially became worse. Without testing, that is the surest way to know that he has it–they become worse after treatment starts. But within 2 weeks he is moving better than I have ever seen him and I think he might have been carrying this since I’ve owned him, now 5 years. I’ve seen many horses recover from this with Marquis. Invest the money. Get a payment plan. If your car needed $1200 in repairs would you start taking the bus of find a way to pay? And don’t wait–you’ll just have to do the marquis longer, which will cost a lot more.
June 21st, 2010 at 7:46 pm
I am so worried I took my filly to the vet because of a change in behavior and she began bucking with the trainer. I couldn’t believe it. This is so unlike her. She has always been so easy going and never has tried to buck. Anyway, the vet is going to do a spinal tap as she showed me the documentation that most of the horses in the Midwest will test positive for EPM as it is so prevalent when a blood test is done. The only positive way to know is a spinal tap. My filly is just 5 years old and my baby. I had been so looking forward to having some more training and being able to ride her this summer. The vet feels we caught it early and the prognosis is good. I would be very interested in hearing about any additional supplements that might help in the healing process. I will be giving the marquis and just praying she will get better. How long before you see improvement and how long before they are able to be ridden again? Lois
June 25th, 2010 at 9:34 pm
My 36 year old mare was diagnosed with EPM last week after becoming uncoordinated, stumbling and leaning to one side. She is in great shape otherwise. I started Marquis and 8,000 IU Vitamin E daily about 7 days ago. Three days into the treatment she suddenly became agressive and almost ran me down – not her usual sweet disposition. The next day she was back to her normal behavior…not sure what that was all about. I’m not sure if I’m seeing any change in her movement or not at this point. The medication sure is expensive. Can’t imagine having to pay this cost for 6 months, but she is my “baby” and I just can’t NOT help her. Anyone else notice any behavioral changes during early treatment? Do the herbs really work?
September 1st, 2010 at 6:00 am
Smokey was diagnosed with EPM and went through two months of treatment with Marquis. He came out of it fine.
he developed thrush in his front feet–I’ve treated him for that and it doesn’t appear he has any left. But, yesterday he came out of his stall dead lame. Mostly in his left front foot, but intermittently in his right as well.
My question. Could this be a reoccurance of EPM appearing in the front? It doesn’t appear to have the same reaction. His first symptoms was the common dragging of his hind feet. We caught it
the first day he had the symptoms.
I have a horrifying thought it might be Navicular–but I thought I’d get the EPM thought out of my head.
the farrier is coming today to check on the thrush situation–possibly in a place I can’t see (or smell). The vet will be out with her X-ray machine.
I’d just like to know if any of you have had a similar situation.
Thank you
Pat
September 20th, 2010 at 7:35 am
I have just started treating my 18 year old Standardbred mare with Marquis 9 days ago. After the second dose, she had a gas colic. Then after the fourth dose, she had another gas colic. It seems like she has been slightly uncomfortable ever since the colics. Has anyone else noticed gas or colic while their horse was being treated on Marquis?
She has only been on a half dose since the 2 colics, but the vets want me to start increasing her again to her appropriate dose, but I am terrified to do so. I just can’t take another colic.
She is also getting 10,000 IU Vit E, probiotics, and SmartPack Succeed to help boost her immune system, but I am about ready to quit this Marquis because I’m so scared on another colic.
Anyone else have this problem?
Thanks,
Emily
December 27th, 2010 at 9:54 pm
My 10y/old thoroughbred Lily had some health issues in the fall of 2009 and spring of 2010.Tested negative for EPM and herpes as well as lime disease. Had some muscle loss and lip drooping. Had a basketball size hematoma right hind. Two vets saw her and did not recommend Marquis or anything else for epm. Did give her 2 rounds of SMZ’s and then 5 days of IV gentamycin. She got better but never well. Then started showing increased neurological signs in hind. Started her on a medicine for epm that is from a compound pharmacy and prescribed by me vet. Have given it almost a week. Wonder when I should notice improvement. Anyone have any advice?
Thanks
Carolyn
January 7th, 2011 at 12:32 pm
You can find Marquis at Smartpak… for the 28 days it is $759.95. It is expensive, but it isn’t $1200 a month as others have stated.
March 21st, 2011 at 10:43 am
My 22 going on 23 year old SSH/Arab was just diagnosed Thursday evening with EPM (via the IFAT UC Davis test).
I ordered the Marquis through Allivet (the cheapest I could find at $739 for 4 tubes and free shipping), I did see it as expensive as $1100, but look around prices vary widely
It came today and I am starting treatment this afternoon. Vet is also having him get 2x dose liquid vitamin E and Duralactin, along with his normal cocosoya, selenium and senior hoof/joint supplements.
April 8th, 2011 at 4:00 pm
Hi, I have a question, how long till you know if ya horse is recovering and you can start back to ride a horse that has EPM?What kind of exercises do you do with them? I have been given a NICE 2yr old that was diagnosed and treated for EPM last summer 2010 and he is at the trainers now. He rides not too bad but is off a little. Will he ever fully recover? Is it possible he could make a barrel horse someday? He is a super nice bred colt, as the stud fee for him was $5000 alone. Should I get him and treat him with Marquis, and just take it slow with him for a year and see if he recovers fully, or not waste and time or money on him? Any info and knowledge would be great! Thanks Stassi
August 10th, 2011 at 12:09 pm
Someone tell me the Marquis will work. 4 Vets and 2 yrs later, I. Had to ask for the EPM blood test. She is my “Dreams Come True” . Does anyone know, do I do any physical theropy or anything while on the meds and vitiman E? Is there something else I should be doing? She is my HEART, I don’t care if I never ride her again, I just want her to be ok.. we are on day 9 of the Marquis, how do I know if I need another round of treatment after the 1st 28 days? There are so many varibles. Would like to hear from someone with experience using this medication. Sending Prayers to all that need them, Kathy <3
August 26th, 2011 at 11:38 am
Hello Folks,
My 4 year old gelding has been treated for EPM. His story goes like this, since I bought him at a week old he would have intermittent low grade fevers lasting a day approx. 2 – 3 times a year. It was always the same, blood work came back fine and diagnosed as fever with unknown origin. He is a real character. Very playful with those horse balls they sell (never saw a horse actually play with those until him). I had him gelded at 3 yrs. old because I felt guilty and wanted to be fair to him. He had a fever the next day which is assumed to be a reaction to the 4 way vaccine. I sent him to the trainer and he was there for one month when the trainer called me and said that he left crumbs in his feed bucket and was standing in a different spot in the pasture and pawed twice. I immediately thought, he has a fever. He did, 104.3. I couldn’t believe it was so high, he was treated. I checked him in the A.M. He was acting perfectly normal. His temp. was 105.6. Contacted the vet and while waiting for her arrival I treated and rinsed to cool him down. I noticed his eyes were jaundice. His blood work showed his bilirubin was slightly elevated and he was tested for pirosplasmosis. Thank goodness he was neg. I was very concerned and took him to a hospital in Ocala, FL for further eval. I had insurance on him so that was very helpful. Same thing, fever of unknown origin. Took him home for 1 month. During his time home I noticed he didn’t play anymore, thought it was my baby growing up. He went back to the trainer for 2 more months and then came home. I was so excited to finally start riding my baby. We were doing well, however I started to notice after I would work him he would slip in the back once or twice frequently. In October of 2010 while feeding I noticed his face looked extremely different. Both masseters had atrophied. It was so sudden!! I pay very close attention to my horses and notice every little detail. The vet came out and did a neuro exam on him. He was slightly weaker to the Left. There are only two reasons for masseter atrophy, neurological and eye problems. She suspected EPM, however he was an odd case and hard to figure. Bl. work done and he was positive for EPM in the serum. She wanted to do a spinal tap to be certain, however I couldn’t afford it. I decided to go ahead and treat him because this was the closest diagnosis yet. Several tests were run on him, however the fevers were throwing the vets off. Could not renew insurance ref. financial strains, 3 months later the nightmare began. Obviously, I had to go with the cheaper compounded medication. He was on that from Jan. – March 2011. Nothing much to report other than the vet coming to reassess him and blood work. She contacted me to tell me he was anemic. Possible side effect from the medication or the possibility that there is a underlying cause. The medicine was stopped and he kept declining, 3 points away from a blood transfusion. He then gradually started to elevate on his own once the medication was out of his system. We had to end up doing a spinal tap anyhow to determine if we were really dealing with EPM. It was Positive with a moderate response, 30. We then continued treatment with the Marquis. It was great. He regained all the muscle in his face, I could not believe it!! At the beginning his head looked like that of an anorexic horse but his body was that of a very healthy, very built horse. This is not the typical signs of EPM. Although what is typical? There are so many variations to this disease that it is frustrating for the vets and owners. He finished treatment in May. He was doing GREAT!! Started playing again!! I started riding, just walking around for approx. 15 – 20 min., no more slipping in the back. That was for 1 month. Then I noticed he was dragging his hind legs, knuckling over, and having trouble turning in a small circle to the right. He would basically freeze up and start backing like he just couldn’t get his body to go that way. Vet is out again, I was afraid of a relapse. His neuro exam was fairly unremarkable when she came out, however he was having obvious Right hind pain, possibly in the hip. I was confused because some days he is worse than others. He ended up having an abcess on the right hind coronet band and once that ruptured he was doing a little better for a few days. I wasn’t convinced that was the whole story. I called the vet back to do another neuro exam and this time she witnessed the knuckling over and the right sided problems. I also noticed that his masseters were starting to atrophy slightly. He started the Marquis this week. I am going to treat him for 2 months this time. I wish I would know if this is a relapse, re-exposure, or if he wasn’t treated long enough the first time. Unfortunately, this is my last attempt at treating him do to finances. It has been so expensive and has affected me being able to properly vaccinate and keep up with other maintenance on my other horses (teeth, worming, etc….). I am very thankful to my vet because if she didn’t help me (payments), I wouldn’t have been able to treat him with this expensive medication. I couldn’t give up on him yet. I wish I never had to. I hope this treatment works. I hate the thought of me having to let my baby deteriorate until it’s time to euthanize.I realize it might be years, however it is the unknown. MY POOR BOY, I LOVE HIM SOOOOOO VERY MUCH!!!! I hate opossums!!!!!!!!!!! I believe I would rather my horse be struck by lightening than go through this.
I wish all of you the best of luck with your babies. I am so sorry this is so lengthy, but this is not the usual case and if it helps any of you that would be worth it.
Take Care,
Cindy
October 13th, 2011 at 6:14 pm
My daughter has an 18 year old horse that was diagnosed 4 months ago with epm. The vet put him on a mediation that I do not know the name of it, we just have to give him a dose in his mouth every day for four months at $150/month! He seems almost fully recovered though, from that and a lot of theraputic exercise.
Does the vitamin e really help?
January 12th, 2012 at 6:37 pm
I aquired a 16 year old TB who had had EPM and was still on her meds. She is doing just fine. Three months later my arab mare, who I have owned since her birth, began showing signs (uncoordinated, dragging hind legs, confused). The vet said I did a good job catching it so early. My TB was on Pyrimethamine/Sulfadiazine (not sure what her initial treatment was), and I am starting my Arab on Marquis this week. My vet had me give her banamine for a week and she got remarkably better. Good thing about being diagnosed with EPM- very treatable, and it’s not Rabies.