A study entitled “Eosinophilic Enteritis in Horses with Motor Neuron Disease” describes the laboratory results, clinical features, and postmortem findings regarding a group of young horses with motor neuron disease. The disease—abbreviated MND—is thought to be linked to vitamin E deficiency, and possibly to have a link to difficulty in absorbing vitamin E, as well as being linked to genetics, environment, management, and diet.
The study, published in the March 2016 Journal of Veterinary Internal Medicine, examines a group of fifteen Andalusian horses ranging in age from one- to three-years old that developed muscle atrophy, fasciculation, paresis, weakness, and weight loss following a lack of green foliage in their diet caused by barren pastures and supplements of poor quality hay. The horses followed a normal deworming schedule and there was a population of horses on the same farm with differing diet and management who were unaffected.
The five most affected horses of the group were deemed beyond recovery and euthanized. Their bodies were subjected to a thorough postmortem examination during which time muscle specimens were collected from the M. sacrocaudalis dorsalis medialis and the M. gluteus medius muscles, and tissue samples were collected and preserved from the brain, spinal cord, cervical, thoracic, lumbar, and sacral segments, and of the heart, lung, liver, spleen, lymph nodes, kidneys, bladder, stomach, and small and large intestine.
The five euthanized specimens were shown to have catarrhal enteritis of the ileum and jejunum. Large, ciliated protozoa resembling B. coli, an opportunistic pathogen in animals already affected by other disease and which has been associated with intestinal diseases in some primates, were also found. Additionally, there was mild infiltration of eosinophil and lymphocytes found in the vicinity of the protozoa.
The median age of horses affected by EMDN is ten years, and usually there is a minimum of eighteen months before clinical signs appear, but in this case the horses were younger—between one a three years—and clinical signs appeared faster, after only six months. The authors propose a possible cause-effect relationship between the intestinal inflammation caused by enteritis and the protozoa and the ability of the animals to absorb vitamin E, leading to MDN. However, the study is limited by the absence of an antemortem test of the clinical horses’ ability to absorb vitamin E.
Research study authors: E. Díez de Castro, R. Zafra, L.M. Acevedo, J. Pérez, I. Acosta, J.L.L. Rivero, and E. Aguilera-Tejero
To view the research in its entirety go to: http://onlinelibrary.wiley.com/doi/10.1111/jvim.13944/full