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Equine protozoal myeloencephalitis due to Neospora hughesi and equine motor neuron disease in a mule

Authors

  • Carrie J. Finno,

    1. William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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  • Joshua Seth Eaton,

    1. William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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  • Monica Aleman,

    1. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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  • Steven R. Hollingsworth

    1. Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Address communications to:
Dr. C. J. Finno
Tel.: 530 752-0290
Fax: 530 752-9815
e-mail: cjfinno@vmth.ucdavis.edu

Abstract

Case description  A 23-year-old female mule was presented for bilateral ocular abnormalities and an abnormal pelvic limb gait.

Clinical findings  Anisocoria, unilateral enophthalmos, medial strabismus, ptosis, pupillary light reflex deficits, and bilateral reticulated pigmentary retinopathy were observed on ophthalmic examination. Neurologic abnormalities included right-sided facial nerve paralysis, extensive symmetric muscle atrophy, and asymmetric pelvic limb ataxia with an abnormal pelvic limb gait. A positive titer (1:40) for equine protozoal myeloencephalitis (EPM) associated with Neospora hughesi was obtained from cerebrospinal fluid with minimal (<1 red blood cell/μL) blood contamination. Muscle biopsies of the sacrocaudalis dorsalis medialis muscle revealed predominantly type I neurogenic muscle atrophy, consistent with a diagnosis of equine motor neuron disease (EMND).

Treatment and outcome  Treatment included a 2-month course of ponazuril (5 mg/kg PO q24 h), vitamin E (8000 IU PO q24 h), and selenium (2 mg PO q24 h). Clinical improvement was not observed after 2 months although the mule remained stable. Clinical deterioration was reported upon discontinuation of the ponazuril after a 2-month course.

Conclusion  Concurrent disease with EPM associated with N. hughesi and EMND should be considered in cases demonstrating cranial nerve abnormalities, pronounced symmetric muscle atrophy, unusual asymmetric gait abnormalities, and reticulated pigmentary retinopathy.

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