Lame alpaca A 9 month old alpaca had a somewhat uncertain clinical history but he was unable to walk normally when presented for evaluation The physical examination was difficult because of not being familiar with the species - it was not possible to determine if the etiology of the lameness was neurologic or was musculoskeletal. Lateral and ventrodorsal radiographs were made of the thoracolumbar spine. Lateral TL spinal radiographs Enlarged lateral radiographs VD radiograph of the thoracic spine Radiographic findings of the thoracic lesion on the lateral view
- Disc space collapse with endplate destruction
- Shortening of adjacent vertebral bodies with collapse of the intervertebral foramina
- Bone lysis causing destruction of the ventral cortices of the vertebral bodies
- Large perivertebral mass that extends ventral into the thoracic cavity
- No signs of segmental malalignment causing spinal canal compression
Radiographic findings of the thoracic lesion on the VD view VD radiograph offers minimal information because of the superimposed rumenal contents It is possible to imaging the collapsed disc space (arrow) The possibility that the perivertebral mass remains in the perivertebral space, extends into the pleural space, extends into the mediastinal space, or actually represents a pulmonary lesion such as pneumonia should all be considered Radiographic findings of the LT lesion
- The second lesion at T13-L1 is primarily productive involving the cranial portion of the body of L1 (arrow)
- Early narrowing of the disc space is possible
- No segmental malalignment is noted -
Radiographic diagnosis
- The major lesion centers on a disc space with destruction of the adjacent end plates and bony tissue causing shortening of the vertebral bodies - the presence of the perivertebral mass makes it difficult to determine the presence of periosteal new bone - these changes plus the presence of a second lesion are typical for a hematogenous discospondylitis
- The possibility of a perivertebral abscess with extension into the spine could be considered but is unlikely
- Either primary or metastatic bone tumor is unlikely because tumors do not center on disc spaces and the patient is young
- A healing fracture is unlikely because the lesion is primarily destructive and includes two separated lesions
- The destruction of end plates in the major lesion plus the productive nature of the second lesion makes a congenital hemivertebra unlikely
Clinical course
- The lameness developed into a non-ambulatory paresis and the patient was euthanatized
- The major lesion at necropsy was a pathologic fracture with compression in the thoracic spine that was easily visualized - the extension of the perivertebral mass into the thoracic cavity was more difficult to evaluate - the lesion was primarily soft tissue and appeared to remain on the midline in an extrapleural location
- A positive bacterial culture was obtained however, the classification of the bacterium was not made - a primary site of infection was not identified
