Equine protozoal myeloencephalitis in a pony.

The research investigates a case of a fatal neurological disorder in a 10-year-old pony, identifying equine protozoal myeloencephalitis (EPM) as the likely cause.

Study Overview

• The study was initiated following the sudden onset of a neurological disorder in a 10-year-old pony, which subsequently led to its death only five days later. Post-mortem examination of the pony was undertaken to identify the causes behind this unexpected fatality.

Findings from Post-mortem Examination

• During the autopsy, a yellowish discolored area measuring 1.5 x 1 cm was discovered in the medulla oblongata, a part of the brain that controls vital body functions such as heartbeat and breathing.
• A microscopic examination of this affected area indicated two significant abnormalities — necrosis and nonsuppurative myeloencephalitis. Necrosis refers to the death of cells or tissues, while nonsuppurative myeloencephalitis is a type of inflammation of the brain and spinal cord, which does not involve pus formation.

Parasitic Infection

• In addition to the discolored tissue and inflammation, both immature and mature forms of parasitic microorganisms, known as meronts, were detected in the neural tissue and capillaries of the brain stem.
• The size of these organisms was measured as 25 by 10 microns. In structure, they were found to be similar to the parasites seen in cases of equine protozoal myeloencephalitis (EPM) in horses. EPM is a severe neurological disease caused by a protozoan parasite, which can lead to significant damage to the central nervous system.
• This evidence strongly suggests that EPM was the cause of the pony’s neurological disorder and subsequent sudden death.