Ununited anconeal process is a developmental disease of large and giant breeds that affects the elbow joint. In UAP, the bone in the elbow, called the anconeal process, fails to fuse with the ulna. This results in arthritis and lameness if untreated. The German shepherd is by far the most commonly affected breed; however, the disease can be seen in any dog, especially other large and giant breeds.
In a normal dog, the anconeal process develops and then fuses to the ulna by the time the animal is 20 weeks of age. If it fails to do so, chronic instability and irritation can result, which leads to progressive arthritis. Typically, dogs will show a forelimb lameness that improves with rest but worsens with exercise. In 20 to 35 percent of the cases, the disease is bilateral, meaning that it affects both legs, but often, one side will be affected more severely than the other. Dogs are typically presented at six to 12 months of age to a veterinarian because of front leg lameness. Other dogs will not be taken for treatment until they are several years of age, when considerable arthritis is already present.
