Primary cerebellar hypoplasia is a rare autosomal-recessive genetic disease of dogs characterized by central neuropathy of the cerebellum.
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. Congenital cerebellar disorders such as genetic cerebellar malformations/cerebellar malformations of unknown causes and cerebellar abiotrophies appear to be more common in dogs.
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.
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, cerebellar Purkinje cell degeneration (Bavarian Mountain Dog), Dandy-Walker syndrome, cerebellar abiotrophy, neuroaxonal dystrophy and intrauterine canine parvovirus infection, 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.
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