Radiology Case

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Radiographic impression: There is incongruity of the right coxo-femoral joint (a) with remodeling and flattening of the femoral head (arrow heads). There is also remodeling of the femoral neck.

Radiographic diagnosis: Legg-Calve'-Perthe’s disease (aseptic necrosis of the femoral head).

Comments: : Legg-Calve-Perthes' disease occurs in small breed dogs between 6 and 10 months of age. The breeds commonly affected are poodles, terriers, miniature pinschers, and other toy breeds. The disease is generally characterized by a gradual onset of lameness over several weeks, however an acute onset following a traumatic event is possible. The etiology of the disease is unknown.1,2 Ischemia of the femoral head occurs spontaneously leading to necrosis of the spongiosa of the femoral head. The cartilage remains intact due to receiving its nourishment from the synovial fluid. Eventually without an underlying bony support structure, the cartilage of the femoral head collapses and the femoral head and neck undergo remodeling. The collapse of the head leads to the widening of the joint space and the irregularity of the head and neck appreciated radiographically. This incongruity can lead to secondary degeneration of the joint.3 If the disease is suspected and no radiographic changes are seen, follow-up radiographs in 2-3 weeks would be recommended.

In humans, Legg-Calve-Perthes' disease has been linked to hypercoagulability and fibrinolysis secondary to certain protein and clotting factor deficiencies. In the study evaluating these factors in dogs, no abnormal levels were detected.4 Other theories involve a tamponade of the vascular supply of the femoral head secondary to a synovitis; and other researchers have demonstrated that there is a more delicate vascular system in the small breed dogs affected than in the large breed dogs.5,6 The current accepted treatment is femoral head and neck ostectomy for pain relief.

1. Bennet D, May C. Joint diseases of dogs and cats In: Feldman EC, ed. Textbook of Veterinary Internal Medicine: Diseases of the dog and cat. 4th ed. Philadelphia: W.B. Saunders, 1995;2047.
2. Schrader SC. Differential diagnosis of nontraumatic causes of lameness in young growing dogs In: Kirk RW, ed. Kirk's Current veterinary therapy XII: Small animal practice. Philadelphia: W. B. Saunders, 1995;1175-1176.
3. Mickelson MR, McCurnin DM, Awbrey BJ, et al. Legg-Calve-Perthes disease in dogs: a comparison to human Legg-Calve-Perthes disease. Clin Orthop 1981:287-300.
4. Brenig B, Leeb T, Jansen S, et al. Analysis of blood clotting factor activities in canine Legg-Calve-Perthes' disease. J Vet Intern Med 1999;13:570-573.
5. Lucht U, Bunger C, Krebs B, et al. Blood flow in the juvenile hip in relation to changes of the intraarticular pressure. An experimental investigation in dogs. Acta Orthop Scand 1983;54:182-187.
6. Fujikawa K. Comparative vascular anatomy of the hip of the miniature dog and of the normal-size mongrel. Kurume Med J 1991;38:159-165.

Dr. John Feleciano, DVM, DACVR
Dr. Renee Leveille, DVM, DACVR

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