Epizootic of equine protozoal myeloencephalitis on a farm.

The research paper focuses on a study conducted on a group of horses on a farm in central Kentucky evaluating the clinical findings, treatment and long-term outcomes related to an outbreak of equine protozoal myeloencephalitis (EPM).

Study Design and Methodology

• The research was conducted as a cohort study where 21 horses on a farm were observed, out of which 12 developed clinical signs of EPM.
• All the horses on the farm were regularly examined for signs of neurologic disease.
• Blood tests and CSF (Cerebrospinal fluid) were conducted to check for antibodies against Sarcocystis neurona, the causative parasite of EPM.
• Horses were treated for EPM until negative results were obtained for CSF antibodies against S neurona, indicating absence of the disease.
• The blood values were continuously observed for evidence of abnormalities because of the long-term administration of pyrimethamine and trimethoprim-sulfamethoxazole, the standard treatment for EPM.
• Physical, neurological, and fetal necropsy examinations were performed depending on the requirement.

Results

• Over the study period of 6 months, out of a total of 21 horses on the farm, 12 were identified with EPM.
• The treatment duration varied among the horses, ranging from 45 to 211 days with one horse continuously testing positive for the disease.
• The long-term administration of the standard EPM drugs resulted in adverse effects including transient fever, anorexia, depression, worsening of ataxia (lack of muscle control), mild anemia and abortions.

Conclusions

• The study confirmed that EPM can develop as an epizootic, affecting a large number of animals in a region at the same time.
• The initial subtle clinical signs, which were originally understated, later progressed to evident neurological signs reinforcing that early detection and intervention is critical in managing EPM.
• The treatment for EPM not only had side effects but also resulted in worsening of neurological signs, anemia, abortions, and episodes of leukopenia (low white blood cell count) and fever indicating a need for a safer and more effective treatment protocol for EPM.