Sorry to hear Sagan needs surgery.
What does OCD stand for?
OCD stands for osteochondritis dissecans, a painful joint disease that affects shoulders, elbows, and knees.
OCD mainly strikes large-breed dogs, and is fairly common in Golden Retrievers, German Shepherds, Rottweilers, Great Danes, Bernese Mountain Dogs, and Saint Bernards. Not all big breeds are vulnerable: OCD is less likely to affect Doberman Pinschers, Collies, and Siberian Huskies.
Most often the cause is rapid bone development, so OCD is usually found in puppies between four and eight months old. However, it can occasionally be found in older dogs, as well as smaller breeds. It affects male dogs about five times more often than females.
The pain is caused by inflammation and lesions on the smooth cartilage in the dog's joints, right where the bones meet. Small pieces of the cartilage break off and float free in the joint. Those bits of cartilage don't die; they keep growing. (In fact, they even have a painfully cute name: "joint mice.") Once they're floating free, fluid builds up and calcification occurs. The joint gets inflamed and swollen, nerves get irritated, and the pup is in pain.