Retrospective Evaluation of Horses Diagnosed with Neuroborreliosis on Postmortem Examination: 16 Cases (2004–2015)

Abstract

BackgroundEquine neuroborreliosis (NB), Lyme disease, is difficult to diagnose and has limited description in the literature.ObjectiveProvide a detailed description of clinical signs, diagnostic, and pathologic findings of horses with NB.AnimalsSixteen horses with histologically confirmed NB.MethodsRetrospective 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.ResultsSixteen 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.Conclusion and Clinical ImportanceDiagnosis 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.

Utility of C‐reactive protein and serum amyloid A in the diagnosis of equine protozoal myeloencephalitis

“…Any inflammatory process within the horse could cause a rise in acute phase proteins. Many horses are exposed to Borrelia burgdorferi and subsequently develop antibodies without clinical disease; although subclinical inflammation might be present 21, 22. Horses are commonly exposed to viruses and bacteria that can lead to respiratory or gastrointestinal infections, and these problems might trigger systemic inflammation.…”

Lyme borreliosis in the horse: A mini-review

“…The variation reported in presenting complaints reflects the multisystemic nature of Lyme borreliosis. Uveitis has been reported to be the most frequent extraneural manifestation of Borrelia infection (Johnstone et al, 2016).…”

“…However, when presented with a horse displaying ataxia, cranial nerve deficits, and weight loss, with historic or current evidence of uveitis, collapse, or dysphagia, one should consider Lyme borreliosis regardless of CSF analysis or serological results (Johnstone et al, 2016).…”

“…Clinical signs in horses attributed to B. burgdorferi include low grade fever and lethargy (Burgess & Mattison 1987b;Magnarelli et al, 1988;Johnstone et al, 2016), weight loss (Johnstone et al, 2016), changes in behavior (Johnstone et al, 2016), dysphagia (Johnstone et al, 2016), lameness (Browning et al, 1993), arthritis (Burgess et al, 1986;Hahn et al, 1996;Passamonti et al, 2015;Johnstone et al, 2016), neck stiffness (Johnstone et al, 2016), episodic respiratory distress (Johnstone et al, 2016), muscle tenderness and fasciculations (Johnstone et al, 2016), anterior uveitis (Burgess et al, 1986;Hahn et al, 1996;Johnstone et al, 2016), cranial nerve deficits (Johnstone et al, 2016), ataxia (Johnstone et al, 2016), meningo-encephalitis (Burgess & Mattison 1987b;James et al, 2010;Imai et al, 2011), abortion (Sorensen et al, 1990), cardiac arrhythmias (Johnstone et al, 2016) and foal mortality (Burgess et al, 1987a). Ataxia was characterized by general proprioceptive deficits and was frequently reported in conjunction with limb paresis.…”

“…The breed was not known in one of the cases studied. The horses were not vaccinated against Borrelia (Johnstone et al, 2016).…”