The elbow is an important joint. The dog carries about 65% of his weight on his front end. Not only do the front legs bear most of the concussion when a jumping dog lands, they also provide a good deal of the propulsion necessary to launch him into the air. The shoulder and elbow joints absorb most of the impact during movement, and can really put some stress on the joints of the forelimb!
Elbow dysplasia is a group of congenital elbow diseases in dogs. Specifically, there is malformation of the elbow joints, and because of the malformation, the bone or cartilage can be damaged, thereby starting the process of osteoarthritis. Large breed dogs such as the Rottweilers are predisposed to this disease.
This term is used to describe several developmental abnormalities of the elbow joint, including fragmented coronoid process of the ulna, OCD of the humeral condyle, un-united anconeal process, and joint incongruity (the bones don’t fit together properly). Dysplasia refers to abnormal development, in this case of the elbow joint.
Elbow dysplasia is the most common cause of front limb lameness in the young dog, especially of the larger breeds. The elbow is formed from the meeting of three bones:
1. the humerus, which is the boney support of the upper limb from the shoulder to the elbow.
2. the ulna, which runs from the elbow to the paw along the back of the limb.
3. the radius, which supports the major weight-bearing along the front of the lower limb.
All three of these bones need to grow and develop normally and at the same rate such that they fit perfectly at the elbow. If there are any abnormalities along these lines or if the cartilage lining the elbow joint does not form properly then “dysplasia” or abnormal formation is the result.
Elbow dysplasia can take several different forms:
♦ ununited anconeal process (UAP)
♦ fragmented medial coronoid process (FMCP)
♦ osteochondritis dessicans of the medial humeral condyle (OCD)
♦ ununited medial epicondyle (UME)
Elbow incongruity all qualify as types of elbow dysplasia that can be present individually or in combination. While all of the variations are distinct and develop in different ways, they have in common that they produce loose pieces of bone and/or cartilage within the joint that act as irritants much as a pebble does in your shoe! All of these variations also have in common that they develop arthritis within the elbow. The term “arthritis” simply describes inflammation within a joint. The longer an elbow joint is ill-fitting or irregular, the more arthritis forms.
The Cause of Elbow Dysplasia
Elbow dysplasia, like hip dysplasia, is a multifactorial disease. Both genetics and environment may contribute to the development of the disease. Traumatic episodes may affect the development of the elbow joint, such as rough play, accidents and repetitive movements that are unnatural for a young dog (walking stairs/jumping in cars).
Symptoms of Elbow Dysplasia
The first sign of a problem is a mild to moderate front limb lameness. Cases may become apparent during puppyhood, often around 4 or 5 months of age to 10 months. Affected dogs may be lame all the time, or the lameness may come and go. The dog may be stiff for the first few minutes after rising. Both legs may be affected making it hard to tell the dog is lame. He may stand with his elbows close to his chest and be painful when the elbow is extended. Examination of the elbow may show pain, thickening or swelling, and restricted movement. At 5 months, x-rays will show if the anconeal process is not united. If the problem is one of the other components of elbow dysplasia, it may not show up on an x-ray until the dog is over a year old. If the problem is not diagnosed at this stage, more marked lameness may be noted as severe arthritis sets in. Large breed dogs predominate in the commonly affected breeds with elbow dysplasia.
To find out for sure about dysplasia, radiographs are necessary and this generally involves some sort of sedation to minimize the patient’s discomfort as their elbows are properly positioned for the picture. Sedation also helps the veterinary team control the dog’s position better so they can minimize the number of radiographs needed in order to get one good diagnostic view. Dogs that show lameness will likely develop degenerative joint disease over time. For every lame dog, there are many more with subclinical disease. These dogs may become lame at a later time.
Treatment for Elbow Dysplasia
Some cases may be managed with open joint surgery. Early surgical management of these problems provides the best chance for minimizing arthritic changes in these elbows, but virtually all dysplastic elbows will develop arthritis. Older dogs, where arthritis is well established, may still benefit from arthroscopic surgery but the benefits are less predictable. Others may do well with medications alone such as anti-inflammatories. The newest generation of canine anti-inflammatory drugs and diets high in omega-3 fatty acids can also provide some relief.