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From The Orthopedic Foundation for Animals (OFA)

Elbow Dysplasia

Elbow dysplasia is a general term used to identify an inherited polygenic disease in the elbow of dogs. Three specific etiologies make up this disease and they can occur independently or in conjunction with one another. These etiologies include:

1. Fragmented medial coronoid of the ulna
2. Osteochondritis of the medial humeral condyle in the elbow joint
3. Ununited anconeal process

Studies have shown the inherited polygenic traits causing these etiologies are independent of one another.
The most common etiology is fragmented medial coronoid of the ulna. The clinical signs involve lameness which may remain subtle for long periods of time. No one can predict what age lameness will occur in a dog due to a large number of genetic and environmental factors such as degree of severity of changes, rate of weight gain, amount of exercise, etc. Affected dogs are frequently lame or have an abnormal gait. This gait may be characterized by excessive inward deviation of the paw which raises the outside of the paw so that it receives less weight in attempts for the dog to distribute more mechanical weight on the outside (lateral) aspect of the elbow joint away from the lesions located on the inside of the joint. Range of motion in the elbow is also decreased. A normal dog will have two fingers width distance between the point of the shoulder and the wrist (radiocarpal joint) when flexed. An increased width of greater than two fingers is usually present in dogs with elbow dysplasia. Frequently, there is bilateral disease.

References

1. Read RA, Osteochondrosis and Elbow Arthrosis in Young Dogs, Incidence, Diagnosis and Management. Waltham International Focus, Vol 3 No 2, pp 2-10, 1993.
2. Read RA et al. Relationship between physical signs of elbow dysplasia and radiographic score in growing Rottweilers. JAVMA, Vol 209, No. 8, pp. 1427-1430, 1996.
3. Padgett GA et al. The inheritance of Osteochondritis Dissecans and Fragmented Coronoid Process of the Elbow Joint in Labrador Retrievers. JAAHA, Vol 31, pp. 327-330, 1995.
4. Keller GG, et al. Correlation of Radiographic, Necropsy and Histologic Findings in 8 Dogs with Elbow Dysplasia. Vet Rad & US. Vol. 38, No. 4, 1997, pp. 272-276.
5. Berry CR. Evaluation of the Canine Elbow for Fragmented Medial Coronoid Process. Vet Rad & US. Vol. 33, No. 6, 1992, pp. 273-276.

Polygenic

Coming from more than one ("poly") gene pair. These traits are more complex than the typical dominant or recessive genetic trait. The additive interaction of the genes can cause variable results and the gene can be easily passed on to other generations without being identified.