Equine degenerative myeloencephalopathy in five Quarter Horses: clinical and neuropathological findings.

The research paper describes the investigation and findings related to Equine Degenerative Myeloencephalopathy (EDM), a disease that affects horses, in five young female Quarter Horses. The authors aim to shed light on the clinical signs, pathologic results, radiographic and histopathological findings in these horses afflicted by EDM.

What is EDM and its implications

• Equine Degenerative Myeloencephalopathy is a disease that predominates in young horses, causing gait abnormalities, ataxia that’s evident more in the hindlimbs, along with spasticity.
• Despite various theories proposed by authors, the exact cause of EDM remains unclear. A familial predisposition coupled with risk factors such as deficiencies in vitamin E and copper, exposure to toxins, or overcrowded, grassless paddocks might play a crucial role in the disease’s pathogenesis.
• The controversy is the theory of vitamin E deficiency. Some authors reported low levels of plasma or serum α-tocopherol while others found regular values in EDM-affected horses. However, decreased incidence of the disease after the administration of vitamin E supports the theory that it may play an essential role in the disease’s pathogenesis.

Methodology and Results

• The five female Quarter Horses, aged between 12 to 18 months, were admitted for chronic gait abnormalities investigation. They were raised in the same stable and underwent a full range of tests, including clinical and neurological examination, blood analysis, radiography, and histopathological tests.
• All the horses shared a similar history, first showing gait abnormalities at about six months of age. Three of the fillies were raised together until they were yearlings and then moved to another farm with a green pasture, while the other two were brought directly from the farm where they had been born.
• The horse’s blood examinations were within the normative ranges. Blood tocopherol values were normal in three horses but decreased in two.

Discussion and Conclusion

• The clinical and neuropathological observations are consistent and indicative of ED, ruling out other differential diagnoses, such as cervical vertebral malformation and inflammatory/infection causes.
• The gait abnormalities in the horses were found to align with more diffuse spinal cord injury. The lack of green grass pastures and a diet of just hay and pellets reinforce the theory of vitamin E deficiency playing a role in the disease’s pathogenesis.
• Post diagnoses, the dams of the EDM afflicted fillies were shifted to another farm, and their foals, born post transfer, were subjected to daily oral vitamin E supplementation. The foals showed no signs of locomotor abnormalities, further substantiating the role of vitamin E in the fight against EDM.