Ununited anconeal process in dogs is one of four conditions that comprise elbow dysplasia. An ununited anconeal process can lead to degenerative joint disease and osteoarthritis, which is characterized by pain and stiffness in joints.
The anconeal process is a small bone of the ulna in the elbow that has the primary function of stabilizing the elbow during weight-bearing. As the ulna grows, in some dogs the anconeal process can separate from the rest of the ulna. This can create a fragment inside the joint resulting in an ununited anconeal process.
What are the causes of an ununited anconeal process in dogs?
There are a number of hypotheses regarding how UAP develops. Most dogs fuse their anconeal process and rest of the ulna between 14-15 weeks of age, but some breeds may fuse later (e.g. 16-20 weeks in the German shepherd dog). It is unclear the reason for the lack of fusion.
The most likely cause is elbow incongruity which leads to excessive force on the developing anconeal process. Repeated microtrauma can damage the center of ossification, which will cause the failure of the union. Although UAP usually only affects young, growing puppies, it can be an incidental finding in mature dogs as well.
UAP is most commonly associated with large breed dogs, such as the German Shepherd, St. Bernard, Bernese Mountain Dog, and Rottweiler. The average age at which these dogs are affected is less than 1 year and UAP is more common in males compared to females.
What are the clinical symptoms of an ununited anconeal process in dogs?
Forelimb lameness and limping are the typical hallmark signs of an ununited anconeal process (UAP) in dogs. Lameness usually occurs at 5-10 months of age and progresses. Lameness is often unilateral, but sometimes it is bilateral.
When your dog is standing, you might notice that one of its elbows is held away from its body and the foot is turned outwards.
How is an ununited anconeal process diagnosed in dogs?
The diagnosis of UAP is based on a combination of clinical signs and radiographic findings. On physical examination, there is noticeable pain at the elbow during manipulation, especially with the elbow in extension and when pressure is applied over the anconeal process. A lateral x-ray of the elbow in flexion is most useful in diagnosing UAP. On the x-ray, UAP appears as an ovoid-shaped radiolucent area adjacent to the ulna, which is diagnostic.
What are the treatment options for dogs diagnosed with an ununited anconeal process?
All dogs with UAP can benefit from management including weight loss if required, low-impact activity, rehabilitation with physical therapy, omega fatty acid supplementation, and anti-inflammatory medications.
Surgical options to correct UAP in dogs
If UAP is diagnosed at 4-6 months, an ulnar ostectomy can be done to fix the elbow and to stop the humeral pressure on the anconeal process. This procedure involves cutting the ulna to help the anconeal process fuse back with the ulna as the dog continues to grow.
If scar tissue develops between the fractured anconeal process and the rest of the ulna, it will be harder for the bones to fuse together. In this case, the UAP fragment should be surgically removed.
What is the prognosis for dogs with an ununited anconeal process?
The prognosis can vary from dog to dog. Optimal functional outcomes and minimal postoperative joint degeneration are only possible if early intervention is undertaken. A recent study of dogs treated by surgical excision for UAPs indicated that the vast majority of owners were satisfied with their pet's post-surgery activity level and rated the outcome as good to excellent.
In conclusion, we discussed the ununited anconeal process (UAP) in dogs. UAP is a condition that leads to degenerative joint disease of the elbow in dogs. UAP is most commonly associated with large breed dogs, such as the German Shepherd, St. Bernard, Bernese Mountain Dog, and Rottweiler. Symptoms of UAP include lameness and limping. UAP is diagnosed based on a combination of clinical signs and radiographic findings. Treatment options for UAP include weight loss, low-impact activity, rehabilitation, omega fatty acid supplementation, and anti-inflammatory medications. Surgery may be necessary in some cases. The prognosis for UAP varies from dog to dog.