Elbow dysplasia is a disease with a high inherited component,
which primarily affects intermediate and large breed dogs.
A high incidence of occurrence has been noted in the Bernese Mountain
Dog, German Shepherd, Rottweiler, Golden Retriever,
and Labrador Retriever. Some of the other
breeds affected are the Newfoundland, Saint
Bernard, Mastiff, Springer Spaniel, Australian Shepherd,
Chow Chow, Shar-Pei, Shetland Sheepdog, and some Terrier Breeds.
Typically, both elbows are affected. However, unilateral elbow dysplasia is not uncommon.
The elbow joint is composed of three bones
(radius, ulna, and humerus) which must all grow together and fit perfectly. The radius and ulna are paired bones with the radius being the main weight bearing bone. The normal elbow joint is
characterized by a smooth transition from the ulnar
articular surface to the radial surface. In
a dysplastic elbow the edge of the ulnar surface lies above the level of the adjoining radius, creating a step between the
radius and ulna and causing incongruity of the joint. The height of the step may
vary from barely noticeable to 4 mm or more. When this occurs the weight bearing force on
the ulna is increased, resulting in excessive pressure on the medial coronoid process.
This leads to fragmentation of the coronoid process. This usually occurs between 5
and 7 months of age. A superficial to deeply grooved "kissing lesion"
is often present on the humeral articular
surface opposite the fragment. A
cartilage flap or OCD (osteochondritis dissecans) lesion may also develop. Secondary
arthritis becomes evident at 6-7 months. Compensatory adjustments during growth may occur in some dogs, tending to minimize
unequal growth rates between the three bones
and moving the ulna distally to better conform to the radius. . However,
excessive force is then placed on the anconeal process at the top of the ulnar articular
surface. This force will cause a failure of
ossification, leading to an ununited anconeal process.
dogs are frequently lame or have an abnormal gait. The gait is often characterized by
excessive paddling or flipping of the front feet. The
animal may either hold the elbows out or tucked in and often stands with the feet rotated outward. Many sit or lie down
much of the time, or play for shorter periods of time than other
dogs of comparable age. They are often described as quiet or even lazy. Frequently, they
are stiff when rising and tire easily. Exercise
typically makes the lameness worse. In dogs with bilateral elbow dysplasia, the
lameness may seem intermittent or shift from one front leg to the other. When both front
legs hurt, dogs do not limp constantly. Rather, they shift weight off their elbows by
altering their gait and stance. These dogs will only "limp" when one elbow is
more painful than the other. On examination, manipulation of the elbow is
often resisted. Swelling and crepitus (grating) may be palpated. The swelling may be worse after
exercise. In some cases, the joint will be thickened. Muscle atrophy may also be present.
The routine monitoring for the presence of elbow
dysplasia is carried out from a lateral x-ray
of the flexed elbow joint taken when the dog is over 12monthsof age. Correct
radiograph technique is critical for making the diagnosis. The grade is derived by
measuring the amount of new bone that has developed as a result of arthritis. Unlike the grading systems for hip dysplasia the
system for elbow dysplasia is used internationally.
It is generally considered that dogs with grade 3
elbow dysplasia should not be used for breeding and that dogs with grade 2 should be
considered a serious risk.
Re-worded by Prof. Bob
Wyburn (BVMS, DVR, PhD, FACVSc, MRCVS)
World Small Animal Veterinary Association