Greyhound meningoencephalitis

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Nodular and diffuse gliosis with perivascular cuffing, characteristic of greyhound meningoencephalitis[1]

Greyhound meningoencephalitis is a polygenetic immune-mediated greyhound-specific neurological disease.

This disease is typified by severe nonsuppurative meningoencephalitis of the cerebrum and periventricular gray matter of the anterior brainstem[1].

Over 21 genes sets are incriminated in this disease, which primarily results in nonsense or missense mutations of major histocompatibility complexes, leading to upregulation of anti-self antibodies directed at neuronal tissue[2]. A possible viral etiology to this immune-mediated disease cannot be excluded, although all dogs are negative when PCR tested for more usual viral etiological suspects[3].

Clinically affected dogs present with depression, fever, dehydration, weight loss and depression over a period of 4 - 7 days.

Prodomal signs may be indistinguishable from kennel cough to lay persons, but usually progress to acute or insidious onset neurological signs including head tilting, ataxia, recumbency, circling, seizures and blindness. The condition is often fatal within a 2 week period.

This disorder can only be confirmed by postmortem examination, with a diagnosis based upon the unique topography of inflammatory lesions[4].

Blood tests, radiographs and CSF analysis are usually unrewarding but MRI studies may reveal non-suppurative lesions predominantly affecting the olfactory lobes and bulbs, frontal, and frontotemporal cortical gray matter, and caudate nuclei bilaterally.

Postmortem examination of brain tissue is usually confirmatory, with characteristic diffuse and focal gliosis and gemistocytosis accompanied by mononuclear cell perivascular cuffing in caudate nucleus and cortical gray matter of the cerebrum and in the periventricular gray matter of the anterior brainstem.

Histologically, this needs to be distinguished from other diseases such as granulomatous meningoencephalitis and hydrocephalus with periventricular encephalitis.

A number of diseases may mimic clinical symptoms including tick-borne encephalitis virus, equine influenza A (H3N8)[5], Aujeszky disease virus, West Nile virus, Steroid-responsive meningitis-arteritis, rabies and canine distemper virus.

Treatment is mainly palliative and a high mortality is associated with the condition.

The use of prednisolone may be prudent given the underlying immune dysfunction involved.

References

  1. 1.0 1.1 Callanan JJ et al (2002) A novel nonsuppurative meningoencephalitis in young greyhounds in Ireland. Vet Pathol 39(1):56-65
  2. Greer KA et al (2010) Analysis of gene expression in brain tissue from Greyhounds with meningoencephalitis. Am J Vet Res 71(5):547-554
  3. Daly P et al (2006) Greyhound meningoencephalitis: PCR-based detection methods highlight an absence of the most likely primary inducing agents. Vet Microbiol 118(3-4):189-200
  4. Terzo E et al (2012) Unique topographic distribution of greyhound nonsuppurative meningoencephalitis. Vet Radiol Ultrasound 53(6):636-642
  5. Yamanaka T et al (2012) No evidence of horizontal infection in horses kept in close contact with dogs experimentally infected with canine influenza A virus (H3N8). Acta Vet Scand 54:25