An 8-month-old JRT presented with ataxia affecting all four limbs since first acquired by the owners at 3 months of age.

 

MRI of the brain only revealed mild supracollicular fluid accumulation in the quadrigeminal cistern causing mild compression of the occipital lobe and rostral cerebellum. CSF analysis and protozoal serology were unremarkable. This type of fluid accumulation is not uncommon in small-breed dogs and has been considered as an incidental finding in more than half of dogs retrospectively evaluated for intracranial disease. Based on an MRI study, occipital lobe compression greater than 14% is likely to cause clinical signs, whereas the degree of cerebellar compression was not considered significantly associated with the occurrence of clinical signs.

 

The video below provided to us showed marked cerebellar-quality ataxia affecting all four limbs, and truncal ataxia. Although subjective here, it was considered that the degree of ataxia was too severe to be explained by the mild mass effect caused by the supracollicular fluid accumulation. Furthermore, hereditary spinocerebellar ataxia was considered a likely differentials in view of the breed and age. DNA testing confirmed that this dog was homozygous for the mutation causing cerebellar ataxia in JRT.

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Courtesy of Daniel Mendoza and Donald Sheahan at Dogwood Vets, England.