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  Discussion on Suspensory injury impacting underlying EPM illness
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New Member:
slinky

Posted on Saturday, Jun 20, 2009 - 10:29 pm:

Dr. Oglesby,

I have a 15 yr old thoroughbred that I have owned for that past 8 years. About 5 years ago he was treated with Marquis for suspected EPM. At the time, he was in amazing physical shape and in the middle of his jumping career. We considered EPM when, at times, he didn't feel "connected" between his front and back-end. He responded very well to the treatment and was considered to have a mild case of EPM. He has had no clinical signs for the past many years until my current situation.

Last July, he was diagnosed with torn suspensory ligaments in both front legs and pulled flexor tendons on the left hind and right front legs. He was put on stall rest for six months and began his rehab with controlled turnout and handwalking. In February, I rode him for the first time undersaddle for 10 minutes, wrapped his legs and the next day they never looked so good. I tried to ride him again and the moment I saddeled him he began to display narcoleptic symptoms. Up to this time in his life, he had never displayed any other neurologic symptoms besides the incident mentioned earlier.

I had a neurologist examine him and she said he was definitely displaying neurological symptoms and considering the small history of EPM, that is probably what it was. His blood titers did come back in the "high" range. Unfortunately I do not know the exact numbers. He was started on 2 months of Marquis and 6 months worth of pyrimethamine. He began treatment in late April.

My mother has been taking care of him during this time (I moved)and according to her, has done nothing but improve. I was able to find a place to keep him that is close to me so he was shipped to my area. Before he left, the neurologist did a follow-up visit and said he improved in the front-end but is now a grade 2 in the hind-end because he was tripping over himself and didn't have the compensatory ability to catch himself. The neurologist said it was impossible to determine if the muscle loss was due to the neurologic impairment or more due to the fact that he went from being worked everyday to stall rest for 6 months. She said he was unsafe to ride "just in case" and recommended that he be started on ground work to build his muscles a little.

He was transported by commercial shipper and spent almost 12 hrs traveling. He arrived to me at about 8am and looked dehydrated and as he relaxed a little, very tired.

The next day he had a seizure in the pasture. It was a minor seizure that lasted about 5-7 seconds and he had no postdictal symptoms besides a little depression. His gums were pale, but I've been reading that anemia is common with his treatment. Within 1 hour he was acting completly normal.

My plan was to start him back to work of normal suspensory rehabilitation and hopefully just get him to the point that he could do flat work.

At this point, I'm lost. I've been reading numerous articles that state the treatment he is receiving is not the best and should be supplemented with vitamins. I guess I'm looking for a second opinion and for some guidance about getting him back to work to help build some of his muscles. With my own patients I know that if they don't use it, they loose it. Wouldn't this be true for him also? Is it worth getting another neurologist to come out and look at him? Is the seizure related to the stress of a 12 hr haul?

Any advice or guidance would be greatly appreciated!

Erica
Moderator:
DrO

Posted on Sunday, Jun 21, 2009 - 10:59 am:

Welcome Erica,
I am sorry to meet you over such a serious problem. I cannot acurrately answer some of your questions with the information available except perhaps the one about what to do next.

I would like for you to reconsider your goals and the prognosis that this horse can achieve them. Let me emphasize that this horse has a history of remarkable multi-leg supporting ligament and tendon injury, a eight month history of at least a grade 2 neurological deficit behind, and intermittent petite(?) mal seizures possibly secondary to past EPM infection which has already been treated aggressively. It sounds to me you might be expecting a bit much at this time but if you are willing to accept a guarded to poor chance of safety with flat work perhaps further work up to better define the problems and consideration of what type medication and management might be of benefit is indicated.

What about the past treatment and management do you specifically find questionable?
DrO
New Member:
slinky

Posted on Sunday, Jun 21, 2009 - 11:16 am:

I've been reading that the pyrimethamine is used in combination with sulfonamides or the trimethoprim/sulfa combinations. He is only on the pyrimethamine. Also, with the anemia it can produce wouldn't it be beneficial to have him on some kind of vitamin? The research I have found recommends folic acid and vitamin E to possibly help the nerve damage.

Erica
New Member:
upzoo

Posted on Sunday, Jun 21, 2009 - 9:38 pm:

Hi Erica -
Sorry you're having so much trouble with your horse. It all sounds very familiar to me because my daughter's 16 year old thoroughbred, Jake, has had similar problems with EPM.
We've had to treat with Marquis three times over the past five years - the first time, his main symptoms were seizures, a slight front-end incoordination and a head tilt. Each time we've had to lower our expectations for him, and now he's a very happily pastured trail horse. He still likes to get out there under saddle but we've found that he does best when he is least stressed. A major stress like shipping would set off his symptoms all over again.
We do supplement with 8000 iu of vitamin E and glucosamin/chonDrOitin.
I don't have any medical background but from our experience if you only intend to do rehab and flat work with him it sounds reasonable to help build his muscles back up, assuming he enjoys the work and isn't stressed by it.
Joy
Moderator:
DrO

Posted on Monday, Jun 22, 2009 - 8:38 am:

Though the pyrimethamine is the main coccidiocide this research suggests that the antibiotic combination should be used Erica:

Vet Parasitol. 1999 Apr 12;82(3):205-10.
Determination of the activity of pyrimethamine, trimethoprim, sulfonamides, and combinations of pyrimethamine and sulfonamides against Sarcocystis neurona in cell cultures.

Lindsay DS, Dubey JP.
Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Blacksburg 24061-0342, USA. lindsayd@vt.edu

Equine protozoal myeloencephalitis (EPM) is a neurologic synDrOme in horses from the Americas and is usually caused by infection with the apicomplexan parasite, Sarcocystis neurona. The activities of pyrimethamine, trimethoprim, sulfachloropyridazine, sulfadiazine, sulfadimethoxine, sulfamethoxazole, sulfamethazine, and sulfathiazole were examined against developing S. neurona merozoites in bovine turbinate cell cultures. A microtiter plate host cell lesion based assay was used to determine the effects of agents on developing merozoites. A cell culture flask assay was used to determine if selective concentrations of the agents killed or only inhibited development of S. neurona. Pyrimethamine was coccidiocidal at 1.0 microg/ml and trimethoprim was coccidiocidal at 5.0 microg/ml. None of the sulfonamides had activity when used alone at 50.0 or 100.0 microg/ml. Combinations of sulfonamides (5.0 or 10.0 microg/ml) with 0.1 microg/ml pyrimethamine demonstrated improved activity.

A good general vitamin supplementation, without folic acid, is indicated for horses that do not have free access to green pasture for at least 6 hours a day. High levels of vitamin E are not clearly beneficial with EPM but can be therapeutic for similar diseases. NOTE WELL: folic acid supplementation is contraindicated with prolonged oral antibiotic administration. For more on why this is and appropriate folacin supplementation see the treatment section of the article on EPM.
DrO
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