Cerebellar Hypoplasia

Cerebellar hypoplasia is a condition in which the cerebellum does not develop completely. The cerebellum gives your dog balance, coordination and posture. The dog typically has a tremor that does not worsen as the animal matures, and affected animals can be good pets. Hydrocephalus can also be seen in animals with a cerebellar disorder.

Hereditary Cerebellar Hypoplasia

A hereditary form has been reported in Airedales, Chow Chow, and Gordon setters. A non-hereditary from has been described in the Bull Terrier, Dachshund, Weimaraner, Cairn Terrier and Labrador Retriever. Signs are similar to those observed in cerebellar degeneration in which the fist signs appear at about 4-8 weeks of age and consist of lack of coordination of the hindlegs. This increases in severity and the pup adopts a stance with the legs apart. Some dogs develop a tremor of the head, which becomes more pronounced when walking or running. The sense of balance is disturbed and falls are frequent. In cerebellar hypoplasia, the above signs are observed shortly after birth when puppies first begin to crawl. Some puppies compensate and make good pets. Cerebellar hypoplasia shares many morphological features with primary CCD, both conditions being characterised by decreased cerebellar size, with reduced numbers of Purkinje and granular cells. CCD has been identified in many canine breeds. However, cerebellar hypoplasia is different from cerebellar degeneration (cerebellar abiotropy or cerebellar cortical degeneration) in which cells in the cerebellum age prematurely and degenerate, and the signs get progressively worse over time.

Because puppies are normally incoordinated at an early age, they may not appear overly abnormal until they are several months of age. Cerebellar hypoplasia is not a progressive disease and there is no treatment available.

Cerebellar hypoplasia associated with viral infections in newborn animals is most common in cats and cattle. Feline panleukopenia virus (FPV) infection in cats is known to cause cerebellar hypoplasia if infection occurs mid- to late gestation due to destruction of the cerebellar Purkinje cells. Cerebellar hypoplasia and atrophy secondary to feline panleukopenia virus infection are well documented in cats. In dogs, no viral cause has been identified except the canine herpes virus, which causes extensive inflammation in multiple systems of newborn animals. However, recently, parvoviral infection has been implicated.

References:
1. Genetics for Dog Breeders. Roy Robinson
2. Dog Owner's Home Veterinary Handbook. Debra M., DVM Eldredge, Liisa D., DVM Carlson, Delbert G., DVM Carlson, James M., MD Giffin, Beth Adelman
3. Uc Davis Book of Dogs. Mordecai Siegal, Jeffrey E. Barlough
4. Diagnosis of cerebellar cortical degeneration in a Scottish terrier using magnetic resonance imaging. van der Merwe LL, Lane E.
5. Evidence of Parvovirus Replication in Cerebral Neurons of Cats. Angelika Url, Uwe Truyen, Barbara Rebel-Bauder, Herbert Weissenböck, and Peter Schmidt
6. Cerebellar vermian hypoplasia in a Cocker Spaniel. Ji-Hey Lim1, Dae-Yong Kim2, Jung-hee Yoon3, Wan Hee Kim1, Oh-kyeong Kweon