History
An 8-month-old sexually intact male Rottweiler was referred for evaluation of a left pelvic limb lameness of 4 months' duration. The dog had never walked completely normally and had a shifting pelvic limb lameness that had become more evident in the past week. The lameness was partially responsive to treatment with carprofen. On physical examination, the dog had a non–weight-bearing lameness of the left pelvic limb. The left pelvic limb had substantial muscle atrophy, and palpation of the left hip joint revealed signs of pain. Packed cell volume, serum total protein concentration, and blood glucose and urea nitrogen concentrations were within reference limits. Radiographs of the pelvis were obtained (Figure 1).
Ventrodorsal (A) and left lateral (B) radiographic views of the pelvic region of a dog with muscle atrophy and lameness of the left pelvic limb.
Citation: Journal of the American Veterinary Medical Association 233, 12; 10.2460/javma.233.12.1849
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Radiographic Findings and Interpretation
An aggressive lesion of the left hip joint is evident; the acetabulum has a moth-eaten appearance indicative of bone lysis and irregular periosteal proliferation. The left femoral epiphysis is absent (Figure 2). The remaining proximal portion of the left femoral neck is sclerotic. Diaphyseal cortices of the left femur are thin. Left pelvic limb muscles appear atrophied. The acetabulum of the right hip joint is shallow with subluxation of the femoral head. The right femoral neck is thick, and the lateral border of the acetabulum is sclerotic with a faint oval radiolucency. Periarticular new bone formation is also evident at this site.
Same radiographic views as in Figure 1. Notice the aggressive lesion of the left hip joint with a substantial moth-eaten appearance indicative of bone lysis and irregular periosteal proliferation of the acetabulum (black arrows) and complete lysis of the femoral head (white arrow). Cortices of the left femoral diaphysis (white arrows) are substantially thinned, compared with those of the right.
Citation: Journal of the American Veterinary Medical Association 233, 12; 10.2460/javma.233.12.1849
On thoracic radiographs, the fourth thoracic vertebra is shortened with a decreased T4-T5 intervertebral disk space (Figure 3). Adjacent T4-T5 vertebral endplates are sclerotic and irregular. Bridging spondylosis deformans is also evident. There is a focal, well-defined lucency surrounded by an ill-defined sclerotic rim in the caudal aspect of the articular surface of the right humeral head. The caudal aspect of the left humeral head is slightly flattened.
Left lateral (A) and ventrodorsal (B) radiographic views of the thorax of the same dog as in Figure 1. The fourth thoracic vertebra is shortened with a decreased T4-T5 intervertebral disk space. Adjacent T4-T5 vertebral endplates are sclerotic and irregular (black arrows). A focal, well-defined lucency surrounded by an ill-defined sclerotic rim is evident in the caudal aspect of the articular surface of the right humeral head. The caudal aspect of the left humeral head is slightly flattened (white arrows).
Citation: Journal of the American Veterinary Medical Association 233, 12; 10.2460/javma.233.12.1849
Radiographic findings are consistent with left hip joint septic arthritis and T4-T5 diskospondylitis caused by hematogenous spread of infection. Atrophy of the left femoral cortices may be a result of disuse osteoporosis and bone marrow infection. The absence of the left femoral epiphysis indicates complete lysis. Radiographic findings are also consistent with bilateral humeral osteochondrosis and right hip joint dysplasia and degenerative joint disease. The small oval radiolucency in the right hip joint acetabulum may be a lytic lesion suggestive of osteomyelitis.
Comments
The dog underwent surgery for a femoral head and neck ostectomy of the left hip joint. Purulent discharge present in and around the joint capsule was collected for microbial culture and susceptibility testing. The femur fractured during surgery at the proximal third of the bone. The cortex of the femur was thin and pliable with abnormal dark necrotic marrow. The owners elected to have the limb amputated. Samples of the bone and joint capsule were sent for histologic evaluation. The dog recovered from surgery routinely.
Histologic evaluation revealed severe, chronic-active, fibrosing osteomyelitis. Culture and susceptibility test results revealed heavy growth of Staphylococcus aureus. The dog was placed on clindamycin for 2 weeks. By 3 weeks, the owner noticed a considerable increase in overall activity in the dog.
Radiographs taken of the pelvis were characteristic of hip joint septic arthritis on the basis of the aggressive nature of the bony lesions and cross-joint involvement of the femur and the acetabulum. Neoplasia, such as synovial cell sarcoma, would be less likely on the basis of the dog's age and the distribution of lesions. Septic arthritis of the hip joint is a rare condition in small animals.1–3 Most dogs with septic arthritis of the hip joint are mature with a history of prior degenerative joint disease.1–3 Common causes of septic arthritis are direct inoculation (trauma or surgical contamination), extension from soft tissue injury, and hematogenous spread.4
- 1.
Clements DN, Owen MR & Mosley JR, et al. Retrospective study of bacterial infective arthritis in 31 dogs. J Small Anim Pract 2005;46:171–176.
- 2.
Luther JF, Cook JL, Stoll MR. Arthroscopic exploration and biopsy for diagnosis of septic arthritis and osteomyelitis of the coxofemoral joint in a dog. Vet Comp Orthop Traumatol 2005;18:47–51.
- 3.
Schrader SC. Septic arthritis and osteomyelitis of the hip in six mature dogs. J Am Vet Med Assoc 1982;181:894–898.
