The annual American Association of Veterinary Parasitologists met July 19-22 with presentations on many equine-related topics. The EPM Society held a roundtable during that meeting after presentations from top EPM (equine protozoal myeloencephalitis) researchers, discussing topics such as whether horses can be a natural intermediate hosts in the Sarcocystis neurona life cycle, and whether other parasites can cause EPM.

Life Cycle Includes Horse?

The S. neurona life cycle involves the definitive host (opossum) that feeds on muscles of dead intermediate hosts (such as the striped skunk, raccoon, nine-banded armadillo, and cat). The parasite must advance to the sarcocyst stage of its life cycle in an intermediate host’s muscle for an omnivore (such as the opossum) to eat it and continue the life cycle.

Linda Mansfield, VMD, PhD, head of the Emerging Parasitic Diseases Laboratory at Michigan State University, reported on a 4-month-old cross-bred colt euthanized due to severe neurologic problems from EPM. Mansfield found mature parasites in the brain and spinal cord of this colt and mature sarcocysts (contained in muscle cysts) in the tongue