Cerebellar hypoplasia

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The cerebellum of a 3-month-old Cocker Spaniel showing cerebellar vermis hypoplasia (arrow)[1]

Primary cerebellar hypoplasia is a rare autosomal-recessive genetic disease of dogs characterized by central neuropathy of the cerebellum.

A breed predisposition has been observed in the Airedale Terrier[2], Cocker Spaniel, Cairn Terrier, Chow Chow and Great Dane[3].

Cerebellar abiotrophy differs from cerebellar hypoplasia, which involves abnormal development of germinal populations of neuroepithelial cells[4].

Cerebellar hypoplasia in other species is often associated with an in utero or a neonatal viral infection, such as is observed in cats, however this is very rare in dogs[5]. Congenital cerebellar disorders such as genetic cerebellar malformations/cerebellar malformations of unknown causes and cerebellar abiotrophies appear to be more common in dogs[6].

Clinically affected pups show symptoms of neurological disease from 6 - 8 weeks of age, with characteristic ataxia, intention tremors, wide-base stance, head bobbing and limb tremors aggravated by movement or eating.

In many cases, the severity of clinical symptoms peak at 3 - 4 months of age and stabilize, and depending on the severity of cerebellar dysfunction, many dogs may accommodate to the neuropathy and lead relatively normal lives.

Diagnosis is difficult antemortem but a presumptive diagnosis can be made on presenting non-progressive clinical signs, demonstration of negative parvoviral antibody titres, normal laboratory findings and MRI evidence of cerebellar aplasia, partial agenesis or hypoplasia[7].

Histological evidence of cerebellar folial atrophy, degeneration and loss of Purkinge cells and granular cells, and lack of parvoviral DNA in sample tissues is usually diagnostic.

In some dogs, cerebellar hypoplasia can occur secondary to other conditions such as hydrocephalus, Chiari malformations, arachnoid cysts[8], cerebellar Purkinje cell degeneration (Bavarian Mountain Dog)[9], Dandy-Walker syndrome, cerebellar abiotrophy[10], neuroaxonal dystrophy[11] and intrauterine canine parvovirus infection[12], and these should be considered in any differential diagnosis.

There is no known effective treatment for this condition but in most dogs, quality of life is the main decider of continuance of life.

References

  1. Lim JH et al (2008) Cerebellar vermian hypoplasia in a Cocker Spaniel. J Vet Sci 9(2):215-217
  2. Cordy DR & Snelbaker HA (1952) Cerebellar hypoplasia and degeneration in a family of airedale dogs. J Neuropathol Exp Neurol 11(3):324-328
  3. LIDA
  4. Summers BA et al (1995) Degenerative diseases of the central nervous system. In: Summers BA, Cummings JF, De Lahunta A, editors. Veterinary Neuropathology. St. Louis, Mo, USA: Mosby-Year Book. pp:300–305
  5. Summers BA et al (1995) Veterinary Neuropathology. St. Louis: Mosby. pp:82–86
  6. Pass DA et al (1981) Cerebellar malformation in two dogs and a sheep. Vet Pathol 18:405–407
  7. Harari J et al (1983) Cerebellar agenesis in two canine littermates. J Am Vet Med Assoc 182:622–623
  8. Thomas WB (1999) Nonneoplastic disorders of the brain. Clin Tech Small Anim Pract 14(3):125-147
  9. Flegel T et al (2007) Cerebellar cortical degeneration with selective granule cell loss in Bavarian mountain dogs. J Small Anim Pract 48(8):462-465
  10. van der Merwe LL & Lane E (2001) Diagnosis of cerebellar cortical degeneration in a Scottish terrier using magnetic resonance imaging. J Small Anim Pract 42(8):409-412
  11. Fyfe JC et al (2010) Inherited neuroaxonal dystrophy in dogs causing lethal, fetal-onset motor system dysfunction and cerebellar hypoplasia. J Comp Neurol 518(18):3771-3784
  12. Schatzberg SJ et al (2003) Polymerase chain reaction (PCR) amplification of parvoviral DNA from the brains of dogs and cats with cerebellar hypoplasia. J Vet Intern Med 17:538–544