Elbow dysplasia (ED) is a potentially crippling disease of dogs leading to the development of irreversible and progressive arthritis in the elbow joint. Even with early surgical intervention many dogs have chronic pain and lameness. For many veterinarians and breeders, elbow dysplasia is disease that is not only difficult to diagnose, but controversial when it comes to deciding on a dog’s suitability for breeding. The single biggest misunderstanding when it comes to ED is that to be affected a dog must have clinical signs of lameness. Lame dogs are in fact the “tip of the iceberg” with the majority of dogs being asymptomatic carriers, which has caused the disease to spread to very high levels through some breeds.
Causes of elbow dysplasia
Elbow dysplasia (ED) is a broad term used to describe Ununited Anconeal Process (UAP), Fragmented Coronoid Process (FCP) and Osteochondrosis of the humeral condyle (OCD).. All three of these conditions are believed to be due to a failure of endochondral ossification, which is the conversion of cartilage to bone during skeletal maturation. The end result is a weakness in the affected area leading to a flap of cartilage (OCD) or fractures of pieces of bone, which are essential to the stability of the elbow joint (UAP, FCP). The piece of bone floating in the joint is like a pebble in a shoe, causing inflammation and pain.
Significance of Elbow Dysplasia
The consequence of ED is the formation of Degenerative Joint Disease (DJD). DJD (arthritis /osteoarthritis) forms in a joint when there is instability in a joint or as a degenerative process with old age. As the cartilage becomes worn the underlying bone is exposed and because the cartilage cannot repair itself osteophytes (spurs) of bone form. Over time if the instability persists more bone is added leading to more arthritis. Dogs with elbow dysplasia may have severe forelimb lameness or never show any clinical signs. There may be swelling (effusion) in the elbow joint, pain when the elbow is extended, and the paw is often held with the foot rotated outwards.
Reducing the incidence of Elbow Dysplasia
The elbow dysplasia (ED) grading scheme is based on that of the International Elbow Working Group, IEWG, as follows:
Grade 0 = a radiographically normal elbow.
Grade 1 = there is no visible primary lesion but secondary new bone (osteoarthritis) up to 2mm in depth is present at any site around the elbow joint.
Grade 2 = (a) a primary lesion is visible (eg. medial coronoid disease or ununited anconeal process) without visible osteoarthritis OR (b) no primary lesion is visible but osteoarthritis of more than 2mm and up to 5mm in depth is present at any site around the elbow joint.
Grade 3 = (a) both a primary lesion and any amount of osteoarthritis are visible OR (b) no primary lesion is visible but osteoarthritis over 5mm in depth is present at any site around the elbow joint.
The overall grade is that of the worse of the two elbows.
It is strongly recommended that breeders wishing to reduce the risk of elbow dysplasia should select their breeding stock (both dogs and bitches) only from animals with an overall grade of 0. Dogs with elbow grades of 1 show mild or early osteoarthritis which is also likely to be due to ED. They should only be used for breeding with caution, taking into consideration the ED grades of as many relatives as possible, as well as the results of other health tests and characteristics.
Dogs with elbow grades of 2 or 3 have marked osteoarthritis likely to be due to ED, with or without a visible primary lesion. There is a significant chance of ED being passed on to the offspring.