Eosinophilic meningitis

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Medulla oblongata in a dog with eosinophilic meningitis, showing extensive parenchymal loss and replacement with eosinophils and cellular debris[1]

Idiopathic eosinophilic meningitis (eosinophilic meningoencephalitis) is a breed-specific neurological disease of male Golden Retrievers[2], Rottweilers[3], Maremma Sheepdog[4] and Belgian Shepherd Dogs[5].

The cause of this condition is unknown, and in cases where underlying parasitosis is excluded, an allergic reaction to unknown agents is suspected.

Affected dogs usually present with a progressive history of abnormal behavior, asymmetrical cranial nerve deficits, generalized cerebellar ataxia, recumbency, seizures, disorientation, visual impairment, bilaterally decreased menace response and hindlimb conscious proprioception deficits[6].

Blood tests normally show a peripheral eosinophilia. CSF analysis usually reflects elevated eosinophil content and eosinophilic pleocytosis[7].

Magnetic resonance imaging shows diffuse hypointense signalling of the cerebral grey matter consistent with diffuse necrosis or atrophy of the cortical grey matter[8].

At necropsy, eosinophilic infiltration of the brain and spinal cord can be observed, most severe in the medulla oblongata, cerebellum, and cervical spinal cord as well as the liver and small intestines[1].

Histological examination reveals infiltration of eosinophils and macrophages in the subarachnoid space and in the superficial layer of the cerebral cortex.

A diagnosis cannot be established on the basis of clinical signs alone. Patients usually have a predominance of cerebral signs, negative serological tests and eosinophilic pleocytosis.

A differential diagnosis would include granulomatous eosinophilic meningoencephalitis due to distemper[9], neural Dirofilaria immitis, Angiostrongylus spp[10], Neospora caninum, Cryptococcus neoformans, Toxoplasma gondii and Cuterebra spp infections.

The long-term prognosis in most dogs is good, provided aggressive therapy is instituted, usually with initial high doses of dexamethasone followed by a 6-week course of prednisolone.

Daily neurological testing should be performed to assess possible changes in therapy.

References

  1. 1.0 1.1 Olivier AK et al (2010) Idiopathic eosinophilic meningoencephalomyelitis in a Rottweiler dog. J Vet Diagn Invest 22(4):646-648
  2. Smith-Maxie LL et al (1989) Cerebrospinal fluid analysis and clinical outcome of eight dogs with eosinophilic meningoencephalomyelitis. J Vet Intern Med 3(3):167-174
  3. Williams JH et al (2008) Review of idiopathic eosinophilic meningitis in dogs and cats, with a detailed description of two recent cases in dogs. J S Afr Vet Assoc 79(4):194-204
  4. Salvadori C et al (2007) Magnetic resonance imaging and pathological findings in a case of canine idiopathic eosinophilic meningoencephalitis. J Small Anim Pract 48(8):466-469
  5. Henke D et al (2009) Eosinophilic granulomatous meningoencephalitis in 2 young Belgian Tervueren Shepherd dogs. J Vet Intern Med 23(1):206-210
  6. Bennett PF et al (1997) Idiopathic eosinophilic meningoencephalitis in rottweiler dogs: three cases (1992-1997). Aust Vet J 75(11):786-789
  7. Windsor RC et al (2009) Cerebrospinal fluid eosinophilia in dogs. J Vet Intern Med 23(2):275-281
  8. Salvadori C et al (2007) Magnetic resonance imaging and pathological findings in a case of canine idiopathic eosinophilic meningoencephalitis. J Small Anim Pract 48(8):466-469
  9. Grevel V & Machus B (1982) Cytology of the cerebrospinal fluid of dogs and cats with symptoms of meningitis/meningoencephalitis. Part 3. Tierarztl Prax 20(2):199-214
  10. Lunn JA et al (2012) Twenty two cases of canine neural angiostronglyosis in eastern Australia (2002-2005) and a review of the literature. Parasit Vectors 5:70