Thursday, November 23, 2006


This is one disease that causes a great deal of fear and confusion among horse owners and veterinarians. This Neurologic disease is causes by a protozoan parasite that migrates from the intestinal tract to the brain or spinal cord. It is normally found in the feces of possums and armadillos and when they defecate on pastures where horses graze ....they can become exposed.
A very high number of horses are seropositive in the US (about 60% in Florida) but few develop clinical disease. EPM typically has three characteristics 1. Ataxia 2. Atrophy 3. Asymmetry. In other words 1.they stumble 2. have muscle wasting 3. uneven distribution. As the organism replicates in the neural tissue more nerve cells and fibers are damaged causing the neurologic signs.
A complete neurologic exam by a skilled Internist is needed to arrive at a neuroanatomic diagnosis. Once the location of the injury is found then you can better determine the cause. Many neurologic diseases can look like EPM and vice versa so other tests are frequently employed. The main test in use today is a CSF/Spinal tap where a special needle is inserted into the spinal canal and some of the fluid is removed for testing. Specifically we test the fluid for an increase in antibody production to the organism Sarcocystis neurona. If this is positive and the neurologic signs are consistent with EPM , you should begin treatment. If there is blood contamination of the sample then the results can be skewed due to high antibody levels in the serum. The treatment today consists of using a drug called ponazuril or Marquis. This is a 28 day course of treatment that to date has been quite successful. If your horse is stumbling or has focal areas of muscle loss then you should alert your Veterinarian right away so treatment can begin.Technorati Profile

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