Learning that a dog has a genetic disorder is devastating. It's also costly. Hereditary heart malfunctions or orthopedic disorders can often be corrected surgically but the expense can run into the thousands of dollars. With more than 350 hereditary diseases found in dogs, it's good news that scientists are slowly but surely working toward an understanding of the canine genome, the set of chromosomes found in every cell that contain the heritable genetic material that directs the dog's development.