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.

• 易患该疾病的大多数品种，例如凯利蓝梗、边境牧羊犬、澳大利亚卡尔比犬和拉布拉多犬，在6-16周龄时有症状表现。