EQUINE PROTOZOAL MYELOENCEPHALITIS

Equine Protozoal Myeloencephalitis (EPM) is a master of disguise. This serious disease can be difficult to diagnose because its signs often mimic other health problems in the horse and signs can range from mild to severe. The causative organism is a protozoal parasite named Sarcocystis neurona. The disease is not transmitted from horse to horse. Rather, the protozoa are spread by the definitive host the opossum, which acquires the organism from cats, raccoons, skunks and armadillos and possibly even from harbor seals and sea otters. SYMPTOMS • Ataxia (incoordination), Spasticity (stiff, stilted movements), abnormal gait or lameness • Incoordination and weakness which worsens when going up or down slopes or when head is elevated • Muscle atrophy, most noticeable along the topline or in the large muscles of the hindquarters, but can sometimes involve the muscles of the face or front limbs • Paralysis of muscles of the eyes, face or mouth, evident by drooping eyes, ears or lips • 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 Several factors may influence the progression of the disease, DIAGNOSIS If your equine practitioner suspects EPM, he or she may order blood and cerebrospinal fluid (CSF) analysis. If A spinal tap, in which a long needle is inserted through the back and into the spinal canal. A positive blood test only means the horse has been exposed to the parasite, not that it has or will develop clinical disease. Currently three laboratories are analyzing blood and spinal fluid for the prescence of S. neurona antibodies. Prompt, accurate diagnosis is essential and treatment should begin immediately. TREATMENT The sooner treatment begins, the better the horse’s chances are for recovery. Sixty to 70 percent of EPM cases aggressively treated show significant or complete reversal of symptoms. Many horses are able to return to normal activity. Here are some things you should know about treating EPM: • At present, there is one labeled anti-protozoal drug approved by the FDA to treat EPM, consult your veterinarian. • Anti-inflammatory drugs may be prescribed to alleviate symptoms and prevent reactions to parasite die-off during treatment. • Supplementation with vitamin E, an antioxidant, is often recommended to aid healing of nervous tissue. • Average duration of treatment is one month, although depending on which medication is used, can sometimes be longer. • Treatments can be expensive. • Although complications are rare, treatments may affect stallion fertility and may pose certain health risks to unborn foals. • While success rates are high, not all horses respond positively to therapy. Approximately 10-20% of horses may experience a relapse. • While a horse is being treated, taking intermittent blood samples may be recommended to monitor potential side effects such as anemia, low platelet count and low white blood cell count. • Some drugs used to treat EPM are antifolate drugs. Therefore, periodic examination for anemia is indicated during treatment. • Horses undergoing treatment should be closely observed for signs of improvement or decline, especially negative side effects to the drugs, such as acute diarrhea. • Be sure to report any changes in the horse’s condition to your veterinarian. METHODS OF PREVENTION Based on published research, there are several things horse owners can do to protect their horses from infection with EPM. There is currently a vaccine to immunize against Sarcosystis neurona, however, the efficacy is unknown at this time. At best, good horse-keeping practices will discourage unwanted visitors such as opossums and other rodents from contaminating hay, grain and bedding. Reference http://njequine.net/brouchures/EPM.pdf