Pigment retinopathy in warmblood horses with equine degenerative myeloencephalopathy and equine motor neuron disease.

Abstract

OBJECTIVE:

A pigment retinopathy has been reported in adult horses with equine motor neuron disease (EMND) arising from chronic α-tocopherol (α-TP) deficiency. A pigment retinopathy has not been identified in horses with neuroaxonal dystrophy/equine degenerative myeloencephalopathy (NAD/EDM) that affects genetically susceptible young horses with α-TP deficiency. The objective of this report is to describe, for the first time, a pigment retinopathy in a family of α-TP-deficient Warmbloods (WB) with clinically apparent NAD/EDM or EMND.

ANIMALS AND PROCEDURES:

Twenty-five WB horses from one farm underwent complete neurologic and ophthalmic examinations and serum α-TP concentrations were assessed. Two of the most severely ataxic horses were euthanized and postmortem examinations performed.

RESULTS:

Alpha-TP deficiency was widespread on this farm (22 of 25 horses). Eleven of 25 horses were clinically normal (age range 2-12 years), one had signs of EMND (6 years of age), 10 had signs of ataxia consistent with NAD/EDM (1-10 years), and two of these were postmortem confirmed concurrent NAD/EDM and EMND. A pigment retinopathy characterized by varying amounts of granular dark pigment in the tapetal retina was observed in four clinically apparent NAD/EDM horses (two postmortem confirmed concurrent NAD/EDM and EMND) and one horse with clinical signs of EMND.

CONCLUSIONS:

A pigment retinopathy can be present in young α-TP-deficient Warmblood horses with clinical signs of EMND as well as those with signs of NAD/EDM.

• Authors: Carrie J Finno, Heather J Kaese, Andrew D Miller, Giuliana Gianino, Thomas Divers, Stephanie J Valberg
• Journal: Veterinary ophthalmology (Vet Ophthalmol) Vol. 20 Issue 4 Pg. 304-309 (Jul 2017) ISSN: 1463-5224 [Electronic] England
• PMID: 27491953 (Publication Type: Journal Article)
• Copyright: © 2016 American College of Veterinary Ophthalmologists.

Chemical References

• Pigments, Biological
• alpha-Tocopherol

Topics

• Animals
• Brain Diseases (diagnosis, veterinary)
• Female
• Horse Diseases (diagnosis, pathology)
• Horses
• Male
• Motor Neuron Disease (diagnosis, pathology, veterinary)
• Neurologic Examination (veterinary)
• Pedigree
• Pigments, Biological
• Retinal Diseases (diagnosis, pathology, veterinary)
• Vitamin E Deficiency (diagnosis, pathology, veterinary)
• alpha-Tocopherol (blood)