Little did Blackie know that his fate was connected to a syndrome over which he had no control: Black Dog Syndrome. Approximately three years old and a Labrador Retriever mix, Blackie arrived at the Harnett County Animal Shelter in North Carolina on March 2nd. The next day he was adopted! However, the very next day he was returned to the shelter after testing heartworm positive. It was double trouble for Blackie being both black and heartworm positive.