 In a few breeds, such as the Beagle, Rough Collie, and Miniature Poodle, Purkinje cells begin to die off at or shortly before birth, and pups are born with symptoms or develop symptoms by three to four weeks of age.Most breeds prone to the condition, such as the Kerry Blue Terrier, Border Collie, Australian Kelpie, and Labrador Retriever, begin showing symptoms between six and sixteen weeks of age.In a very few breeds, such as the American Staffordshire Terrier, Old English Sheepdog, Brittany Spaniel, and Gordon Setter, symptoms do not appear until adulthood or even middle age.