The hereditary ataxias are a group of neurodegenerative diseases that cause a progressive (or episodic) cerebellar ataxia. A large number of different disorders have been described in different breeds of purebred dog, and in some instances, more than one disorder occurs in a single breed, creating a confusing clinical picture. The mutations associated with these disorders are being described at a rapid rate, potentially changing our ability to prevent, diagnose, and treat affected dogs. A breed-related neurodegenerative process should be suspected in any pure bred dog with slowly progressive, symmetric signs of ataxia.