Retrospective Evaluation of Horses Diagnosed with Neuroborreliosis on Postmortem Examination: 16 Cases (2004-2015).
BACKGROUND
Equine neuroborreliosis (NB), Lyme disease, is difficult to diagnose and has limited description in the literature.


OBJECTIVE
Provide a detailed description of clinical signs, diagnostic, and pathologic findings of horses with NB.


METHODS
Sixteen horses with histologically confirmed NB.


METHODS
Retrospective review of medical records at the University of Pennsylvania and via an ACVIM listserv query with inclusion criteria requiring possible exposure to Borrelia burgdorferi and histologic findings consistent with previous reports of NB without evidence of other disease.


RESULTS
Sixteen horses were identified, 12 of which had additional evidence of NB. Clinical signs were variable including muscle atrophy or weight loss (12), cranial nerve deficits (11), ataxia (10), changes in behavior (9), dysphagia (7), fasciculations (6), neck stiffness (6), episodic respiratory distress (5), uveitis (5), fever (2), joint effusion (2), and cardiac arrhythmias (1). Serologic analysis was positive for B. burgdorferi infection in 6/13 cases tested. CSF abnormalities were present in 8/13 cases tested, including xanthochromia (4/13), increased total protein (5/13; median: 91 mg/dL, range: 25-219 mg/dL), and a neutrophilic (6/13) or lymphocytic (2/13) pleocytosis (median: 25 nucleated cells/μL, range: 0-922 nucleated cells/μL). PCR on CSF for B. burgdorferi was negative in the 7 cases that were tested.


CONCLUSIONS
Diagnosis of equine NB is challenging due to variable clinical presentation and lack of sensitive and specific diagnostic tests. Negative serology and normal CSF analysis do not exclude the diagnosis of NB.
University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, PA.
L K
LK
Johnstone
University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, PA.
J B
JB
Engiles
University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, PA.
H
H
Aceto
Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA.
V
V
Buechner-Maxwell
Cornell University College of Veterinary Medicine, Ithaca, NY.
T
T
Divers
B.W. Furlong & Associates, Oldwick, NJ.
R
R
Gardner
Henderson Veterinary Associates, Elizabethtown, PA.
R
R
Levine
University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, PA.
N
N
Scherrer
Pennsylvania Veterinary Laboratory, Pennsylvania Department of Agriculture, Harrisburg, PA.
D
D
Tewari
Cornell University College of Veterinary Medicine, Ithaca, NY.
J
J
Tomlinson
University of Pennsylvania School of Veterinary Medicine, New Bolton Center, Kennett Square, PA.
A L
AL
Johnson
D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000382:microbiology* / Q000473:pathology; D006736:Horses; D020852:Lyme Neuroborreliosis / Q000473:pathology / Q000662:veterinary*; D008297:Male; D012189:Retrospective Studies
Ataxia; Borrelia; Equine; Lyme disease; Meningitis