EPM
Understanding Equine Protozoal Myeloencephalitis (EPM) in Horses
Equine Protozoal Myeloencephalitis (EPM) is a neurological disease that poses a serious threat to the health and well-being of horses. Caused by a protozoal infection, EPM is one of the most common neurological disorders affecting horses in North America. Despite its prevalence, there is still much to learn about this disease, including how to effectively prevent, diagnose, and treat it. This blog post aims to provide an overview of EPM, its symptoms, causes, and management strategies.
What is EPM?
EPM is a progressive neurological disease caused primarily by the protozoan Sarcocystis neurona, though in rare cases, Neospora hughesi can also be responsible. The disease affects the central nervous system, leading to a range of symptoms that can vary in severity depending on the stage of the infection and the areas of the nervous system affected.
How Do Horses Get EPM?
The life cycle of Sarcocystis neurona involves two hosts: a definitive host (usually the opossum) and intermediate hosts (such as birds). Horses are considered accidental or "dead-end" hosts because the parasite does not complete its life cycle within them.
Horses typically become infected by ingesting food or water contaminated with opossum feces containing sporocysts, the infectious stage of the protozoan. Once ingested, the sporocysts travel to the horse’s bloodstream and eventually reach the central nervous system, where they cause inflammation and neurological damage.
Symptoms of EPM
EPM is known as a "great imitator" because its symptoms can mimic those of other neurological diseases. Early detection and diagnosis are critical for effective treatment. Common symptoms include:
Muscle atrophy, often asymmetrical
Weakness or difficulty standing
Ataxia (incoordination)
Head tilt or abnormal gait
Difficulty swallowing
Seizures or other unusual neurological behaviors
The symptoms often vary depending on the location and severity of the protozoal infection within the central nervous system.
Diagnosing EPM
Diagnosing EPM can be challenging due to its varied presentation and similarity to other conditions. Veterinarians typically use a combination of clinical signs, medical history, and diagnostic tests to confirm EPM. These tests include:
Neurological Exam: Evaluating the horse’s reflexes, coordination, and overall neurological health.
Serology Tests: Detecting antibodies to Sarcocystis neurona or Neospora hughesi in the blood or cerebrospinal fluid (CSF).
Imaging: Advanced imaging techniques like MRI or CT scans may be used in complicated cases.
Treatment Options
If diagnosed early, EPM is treatable, though full recovery is not guaranteed. Treatment typically involves antiprotozoal medications, which aim to halt the progression of the disease by targeting the protozoan. Commonly used drugs include:
Ponazuril (Marquis): An FDA-approved treatment for EPM.
Diclazuril (Protazil): Another FDA-approved medication.
Sulfadiazine-pyrimethamine: An older but still effective treatment option.
In addition to medication, supportive care is crucial. This may include anti-inflammatory drugs, physical therapy, and dietary adjustments to help the horse regain strength and coordination.
Preventing EPM
While it’s impossible to eliminate the risk of EPM entirely, certain management practices can reduce the likelihood of infection:
Control Opossum Access: Minimize exposure to opossums by securing feed storage areas and water supplies.
Maintain Clean Facilities: Regularly clean stalls and feeding areas to prevent contamination.
Monitor Feed and Hay: Ensure that feed and hay are stored in sealed containers or areas inaccessible to wildlife.
Regular Veterinary Checkups: Early detection of symptoms can significantly improve treatment outcomes.
Conclusion
Equine Protozoal Myeloencephalitis is a complex and potentially debilitating disease, but with early detection and proper treatment, many horses can recover and return to their normal activities. By implementing preventive measures and working closely with a veterinarian, horse owners can help protect their animals from this challenging condition.
Understanding EPM and staying vigilant about its symptoms are essential for ensuring the health and well-being of horses. If you suspect your horse may be showing signs of EPM, consult a veterinarian promptly to discuss diagnostic and treatment options.