Clinical history A 10 year old male castrated German shepherd dog presented with a chronic draining tract in the perianal region.
- The patient presented as though having lameness in addition to the soft tissue injury
- Multiple radiographs were made of the pelvic region searching for both muscular or skeletal disease
- What is your diagnosis of these early studies?
Radiographic evaluation
- The hip joints are radiographically normal
- Note the tight fit of the femoral head into the acetabulum
- No new bone response indicating joint laxity
- The lumbosacral region is radiographically normal
- Note the normal alignment between the last lumbar segment and the sacrum
- Note the normal width of the LS disc space without evidence of any reactive new bone
- No evidence of lytic bone lesion is noted
- The ischium just caudal to the left hip joint appears slightly more dense, opaque, when compared with the bone on the right side possibly due to oblique positioning of the pelvis or a difference in thickness of overlying soft tissues
- No reactive periosteal response is noted
- No evidence of radiopaque foreign material or radiolucent gas pockets are noted in the soft tissues
- The urinary bladder and bladder neck are easily identified and appear normal in size and shape
- A diseased prostate gland is not identified
Radiographic diagnosis
- Failure to positively identify a bone lesion suggested use of a tract injection using an iodinated contrast agent to evaluate a soft tissue lesion
- Ventrodorsal and lateral studies made twice following the injection are included for your observation
Radiographic diagnosis
- The contrast column pools within the soft tissues dorsal to the ischium on the left at the site of suspected increased density, opacity, in the ischium
- The contrast column outlines a curvilinear pattern (arrows) seen on both VD studies that suggests a possible linear foreign body
- Surgical exploration of this site located a piece of non-resorbable suture
Comments
- Following discussion of the case with the owner, they made inquires from previous owners and learned of a previous history of surgery in this region
- Positive contrast tract injection has value in identification of the extent of the soft tissue lesion plus the possible identification of a foreign body
- Air can be used as the contrast agent
- This is especially valuable to localization of a lesion in the absence of bony changes
