Dog: Elbow Dysplasia

Other common/scientific names: ununited anconeal process, fragmented coronoid process, joint incongruity

Elbow dysplasia (ED) is a general term referring to the abnormal development of the elbow joint. The elbow is a complex joint formed by three bones: the humerus (the bone in the upper arm), the ulna (the bone from the elbow to the paw at the back of the limb) and the radius (the bone from the elbow to the paw along the front of the limb which supports most of the weight). The joint is supported by ligaments and tendons and encased in a joint capsule. All three of these bones should grow at the same rate for the joint to develop normally. If there are any abnormalities with bone growth or if the cartilage of the elbow joint does not develop properly then elbow dysplasia can result.

Elbow dysplasia can exhibit different forms or a combination of these forms:

• Ununited anconeal process (UAP): this occurs when a bony projection near the top of the ulna comes loose during the growing process
• Fragmented coronoid process (FCP): this occurs when a bony projection on the inner side of the ulna comes loose during the growing process
• Osteochondrosis : this occurs when a flap of cartilage comes off the end of the humerus
• Joint incongruity: this occurs when the bones do not grow at the same rate resulting in abnormal force and stress to the joint

These abnormalities eventually result in arthritis or degenerative joint disease which is responsible for the clinical signs.

Abb. GG0L3M8Q: Elbow Joint.

This is a radiograph of a normal elbow. (A) humerus (B) radius (C) ulna.

The exact cause of elbow dysplasia is thought be a combination of genetic factors, nutrition, trauma and hormonal factors. Elbow dysplasia has a hereditary component with certain pedigrees being more affected. It is more common in large breeds including: Labrador Retrievers, Golden Retrievers, Rottweilers, Bernese Mountain dogs, Newfoundlands and German Shepherds. Dogs fed a diet high in energy and protein may be more predisposed to ED. Repeated stress to the elbow joint during development may contribute to dyplasia. Male dogs are more likely to develop ED than female dogs.

Lameness

Clinical signs of elbow dysplasia are often seen around 5 to 7 months of age. The dog may be lame or limp on a front limb. One or both elbows may be affected. Stiffness after periods of rest is common. The inability to flex or extend the elbow joint may be seen and the joint is painful when manipulated.

Elbow dysplasia is diagnosed by physical examination and radiographs. Advanced imaging techniques such as computed tomography (CT) can aid in the diagnosis. With some cases, a complete diagnosis is made only during arthroscopy.

The Orthopedic Foundation for Animals (OFA) was originally founded to standardize radiographic findings of dogs in regards to hip dyplasia and provide information to dog owners to assist them with the selection of good breeding animals. The OFA also provides evaluation and certification for other orthopedic and genetic diseases including elbow dysplasia. Elbow radiographs are submitted to the OFA and evaluated by three diplomats of the American College of Veterinary Radiologists. The elbow is then classified as normal or having elbow dysplasia of Grade I, Grade II or Grade III. Only normal elbows are given a certification number from the OFA and recognized by the American Kennel Club (AKC). This certification number is public knowledge and listed on the dog’s pedigree. Offspring of OFA-certified parents are less likely to develop ED. Dogs must be two years of age for OFA certification although a preliminary elbow evaluation can be performed on dogs 4 months to 24 months of age.

Abb. GG0LNZZ2: Joint Incongruity.

This is a radiograph showing a shortened radius (B) resulting in an uneven joint. This stress can cause a bony projection to fragment.

Abb. GG0LSWJV: Ununited Anconeal Process.

This is a radiograph showing an ununited anconeal process. In the normal joint, the anconeal process is a bony projection on the ulna. It should turn to bone and unite with the ulna at 4.5 to 5 months of age. The black arrow is pointing to the anconeal process which has not fused with the bone. The white arrow points to secondary osteoarthritis.

Abb. GG0LVL0X: Fragmented Coronoid Process.

The coronoid process is a small piece of bone on the ulna which articulates with the humerus. It should also fuse with the ulna. This is an image of the elbow joint as seen through an arthroscope. The arrows point to the coronoid process which is fragmented causing irritation to the joint.

Abb. GG0N40C0: Fragmented Coronoid Process.

This is a computed tomography (CT) image of a FCP (white arrow). The black arrow points to secondary osteoarthritis.

The objective of treatment is to relieve pain, slow the progression of arthritis and maintain mobility. This treatment may include conservative medical management and/or surgery.

• Medical treatment consists of exercise reduction and weight control. Anti-inflammatory medications specifically NSAIDs (non-steroidal anti-inflammatory drug) are used to relieve pain and inflammation. There are several veterinary manufactured NSAIDs available to veterinarians. Since every dog responds differently, your veterinarian may prescribe different NSAIDs based on its response. Other pain relieving treatments include massage, physical therapy and acupuncture. Chondroprotective supplements such as glucosamine, chondroitin sulfate and diets high in omega-3 fatty acids can also provide some relief.
• Surgery of the elbow joint is performed either through an incision into the joint or with an arthroscope. An arthroscope is a tubular instrument inserted into a joint through a small incision. It uses fiber optics to allow a veterinarian to visualize the joint without creating large incision. The arthroscope is used to remove any bony fragments, damaged cartilage and smooth out roughened joint edges. Medical treatment is also used post-surgery. Exercise is limited to leash walks only for the first 6-8 weeks post surgery to allow joint healing. A gradual increase of activity is then allowed.

Abb. GG0N9W1W: Ununited Anconeal Process.

This is an image of an UAP as seen through an arthroscope.

Surgery is most successful in young dogs with minimal arthritic changes. Some of these dogs may return to normal function. Older dogs with significant arthritis may still benefit from surgery; however, some lameness and stiffness may persist. Dogs with severe arthritis or multiple abnormalities have a poorer prognosis.

Prevention is aimed at breeding only individuals that have OFA certification. Dogs with even mild elbow dysplasia should not be used for breeding. Breed organizations and breed clubs should recognize ED as a problem and encourage OFA certification. Prospective buyers should check pedigrees. If no documentation is available, the dog should not be used for breeding.

A balanced diet should be fed to all young dogs. Protein, energy, calcium or phosphorus should not be overfed. Reducing stress to the elbow joints in young, growing dogs is important. This can be accomplished by maintaining a normal, healthy weight and avoiding excessive exercise.

For dogs undergoing surgery, it is very important that the dog does not lick or pull at the sutures. A special collar (E-collar or Elizabethan collar) is worn by the dog to prevent this. Incisions should be observed daily for swelling, discharge or redness.

If you notice your pup or dog is lame, contact your veterinarian. Early diagnosis of orthopedic problems is the key to successful treatment.