Ununited Anconeal Process is seen most frequently in the larger breeds of dogs. In these animals, there is a separate center of ossification for the anconeal process. This center normally fuses with the diaphysis of the ulna between 4 and 6 months of age. If fusion does not take place at the usual time, the anconeal process becomes partially or wholly detached from the ulna. This condition precipitates secondary degenerative joint disease. The disorder is often bilateral, so it is recommended that radiographs of both elbows be obtained if this condition is suspected or confirmed in one ulna.

A mixed large-breed, 5 years old, male dog was referred to the clinic of Faculty of Veterinary Medicine, Mashhad University, which had a history of lameness of right front limb for 4 days. In clinical examination, it also had a painful elbow joint on deep palpation of olecranon fossa.

For radiography evaluation, flexed mediolateral radiograph of the right elbow joint was taken. This projection revealed a radiolucent line of separation between the anconeal process and the ulna. Since the condition had been present for a long time, changes associated with secondary degenerative joint disease was seen as well, including spurs of new bone around the margins of the joint. As the condition is frequently bilateral, flexed mediolateral radiograph of the left elbow joint was taken to evaluate if the condition is unilateral or bilateral. The radiograph showed both elbows are affected and the radiographic signs were almost the same as right elbow joint.