Introduction

• Several syndromes are recognized:
  • Cerebellar abiotrophies Cerebellar hereditary ataxia.
  • Dandy Walker syndrome Dandy-Walker like syndrome.
  • Hypomyelination/dysmyelination.
  • Neuroaxonal dystrophy Neuroaxonal dystrophy.
  • Leucoencephalomyelopathy Leukoencephalomyelopathy.
  • Congenital malformations of the cerebellum.
  • Cerebellar hypoplasia/aplasia.
• Seen from 6 weeks old.
• Signs: non-progressive cerebellar signs.
• Diagnosis: rule out other causes of similar signs, eg inflammatory and degenerative diseases.
• Treatment: none.
• Prognosis: guarded.

Pathogenesis

Etiology

• Cerebellar abiotrophies: also called cerebellar cortical degeneration - it is a process by which cells develop normally but later degenerate because of an intrinsic cellular defect necessary for continued life of the neuron. Many of these diseases may result from underlying abnormalities of cellular metabolism or function. Known to be inherited in Old English Sheepdog, Gordon setter, Finnish Hound, Italian Spinone, Beagle and Brittany Spaniel.
• Dandy Walker syndrome: is a congenital problem assumed to be associated with abnormal embryogenesis (primarily parenchymal midline developmental field defect of unknown origin). Represent partial or complete absence of the vermis of the cerebellum. Associated with these vermal defects is cyst-like dilation of the fourth ventricle. In addition many of these patients have dilated third and lateral ventricles (hydrocephalus), stenosis of the aqueduct, and absence of the corpus callosum.
• Hypomyelination/dysmyelination: disease is inherited in an X-linked manner is Springer Spaniels.
• Lysosomal storage diseases Storage disease progressive loss of neurone function → cerebellum degeneration.
• Hypomyelination has been associated within uterocanine herpes virus infections Canine herpesvirus disease.

Pathophysiology

• Failure of normal cerebellar development.

• Degeneration of cerebellar neurones after the differentiation process is complete → inadequate function to control movement.
• Dandy Walker syndrome: there is a malformation resulting in a cyst-like abnormality in the cerebellum. The lateral and third ventricles are commonly dilated concurrently.
• Hypomyelination/dysmyelination: disorders of myelin synthesis and maintenance. In most cases the underlying derangement directly or indirectly affects the oligodendrocyte numbers or function.
• Neuroaxonal dystrophy: underlying pathogenesis is unknown. The cell bodies in the grey matter are affected (axonal spheroids) throughout the nervous system except the cerebral cortex. The most severe lesions are in the spinocerebellar tracts and the Purkinje cells.

Timecourse

• From 6 weeks of age (when puppies become more active).

Diagnosis

Treatment

Prevention

Outcomes