Sundays are easy mornings on the backside. The track is closed for training, so we take the horses for a stroll around the shedrows while their stall is cleaned. Everyone shows up a little later than usual, as the work is light and is accomplished in short order.
For the first time today, I administered medication to one of our horses under the care of mi maestro (my teacher/groom) and me. I was distressed last week to learn he was diagnosed with EPM, or Equine Protozoal Myeloencephalitis.
EPM is an infectuous protozoa found in opossum feces. It is also found in intermediate hosts, such as striped skunks, racoons and domestic cats, but it's undetermined if they play a direct role in equine infection. The intermediate hosts injest the sporocysts from the infected opossum feces, which in turn causes the protozoa to grow in the muscle of these intermediates. The unusual life cycle of EPM is completed when the opossom eats the muscle of these infected intermediates.
I've been doing a bit of study on this infection, so I'll try to keep it as simple as I can so we both understand.
EPM is most commonly caused by Sarcocystis neurona which is a single celled parasite. It has the ability to affect any part of the horse's central nervous system (CNS).
Horses become infected with sarcocystis neurona by eating contamintated feed, hay or water, or being out to pasture.
After learning a second horse in our care was just diagnosed with EPM while I was away, I started really looking around to see if I could eliminate any windows of opportunity for opossums to get into our barn and cause trouble. The water is in buckets and on the wall, that appears safe. Hay bundles attached to stall walls also appear to be safe, too. The feed room is cleaned and locked every night, no critters can enter there. But where our hay is stored isn't completely sealed. It's locked, but one of the metal doors as been kicked out to cause the door to crinkle enough for a opossom to enter. I mentioned that door to our assistant this morning. We discussed how to fix that door in serious tones, both of us knowing the best way to treat EPM is to prevent it.
Diagnosis is difficult, but Doc told me he uses blood work to look for antibodies (although as many as 50% of horses could have the antibody for sarcocystis neurona and not have an active infection) and clinical signs which include ataxia (loss of full control of bodily movements), asymmetric weakness, and a voracious appetite. Or, as Doc put it to me, they eat like it's their last meal.
The treatment Doc prefers is sulfonaminde and pyrimethamine, given for 120 days or longer. This is a very difficult protozoa to eradicate, can remain in a latent stage after treatment and relapse is not uncommon. Less than 25% of horses return to normal function. There is no improvement of the CNS damage that occurs before treatment begins.
Like I said earlier, the best way to deal with EPM is to prevent it, if at all possible.
Doc told me today this infection was only discovered about 10 years ago, but he believes it's been around much longer, as he recalls horses who had similiar symptoms and didn't respond to any treatment at that time.
It's a big problem that needs a lot more funding for future research, as so much is unknown about this pernicious parasite.
On a lighter note, I have grown close with a two-year-old filly in our care. She is very sweet and has yet to get her tattoo. I was able to get this picture of us taken before she went out to the track for only her third time.
As you can see, we are bonding well. I'm looking forward to watching her grow into a racehorse. She's a rosebud, not yet bloomed and full of promise.
She is the wind beneath my wings as I drown in her sea of love.