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Vet Ophthalmol. 2017 Jul;20(4):304-309. doi: 10.1111/vop.12417. Epub 2016 Aug 5.

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

Author information

1
Population Health and Reproduction, School of Veterinary Medicine, School of Medicine, University of California, Davis, CA, 95616, USA.
2
Eye Care for Animals, Lees Summit, MO, 64064, USA.
3
Section of Anatomic Pathology, Department of Biomedical Sciences Medicine, Cornell University College of Veterinary, Ithaca, NY, 14853, USA.
4
Department of Clinical Sciences, Cornell University College of Veterinary Medicine, Ithaca, NY, 14853, USA.
5
Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI, 48895, USA.

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.

KEYWORDS:

horse; lipofuscin; neurodegeneration; retina; tocopherol; vitamin E

PMID:
27491953
PMCID:
PMC5292316
DOI:
10.1111/vop.12417
[Indexed for MEDLINE]
Free PMC Article

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