In a recent article by Michelle Powers, et al. (JAVMA, Vol 227, No 7, October 1, 2005, Pages 1109-111), dogs presented from referring veterinarians to Washington State University Veterinary Teaching Hospital with a diagnosis of canine hip dysplasia or hip pain without neurological dysfunction were often found instead to be suffering from cranial cruciate ligament rupture.
While both hip dysplasia and rupture of the cranial cruciate ligament can cause hind limb lameness, a thorough physical examination can usually determine which joint is effecting the lameness, avoiding an incorrect diagnosis. In this study, 32% of the referred dogs actually had stifle problems instead of or in addition to hip problems. Bilateral cruciate problems confounded the proper diagnosis.
Although hip dysplasia is a common diagnostic finding, this report points out that even with radiographic evidence of severe coxofemoral osteoarthritis, most dogs have no clinical signs while rupture of the cranial cruciate ligament usually causes more acute symptoms.
During physical examination of the hip, signs would include discomfort during hip flexion, extension, abduction, or other manipulation. In addition, radiographic evidence of osteophyte development, osseous remodeling, subchondral bone sclerosis, or subluxation of the coxofemoral joint may be seen. Examination of the stifle would include a positive “sit” test, cranial drawer sign with or without cranial tibial thrust, joint effusion, and if chronic, medial buttressing. Radiographic findings would confirm joint effusion, osteophyte development, and possibly show anterior tibial movement.
In addition, the article points out that even severe osteoarthritis from hip dysplasia can often be successfully treated with medical management alone, whereas rupture of the cranial cruciate ligament requires surgical stabilization of the stifle.
The main points to remember when diagnosing hind leg lameness are:
Radiographic signs of coxofemoral joint osteoarthritis do not necessarily rule out other causes of hind limb lameness.
Most dogs with hip dysplasia have no clinical signs.
A thorough orthopedic examination combined with radiographic examination is necessary to properly distinguish between hip dysplasia and cranial cruciate ligament rupture as a cause of lameness.
Bilateral cranial cruciate rupture confounds a possible diagnosis.