Abstract

An approximately three-year-old, 45 kg, wild-caught, female, sand tiger shark presented for abnormal swimming, kyphosis, scoliosis, and anorexia. The shark was housed in a 250,000 gallon salt water exhibit with mixed teleosts and elasmobranchs. Radiographs revealed an acute dorsal vertebral luxation at the level of the cranial dorsal fin. The shark was initially treated with steroids, fluids, vitamins, and assist fed; after treatment she was released on exhibit for monitoring. After one week of improvement her clinical appearance declined. She had an abnormal swim pattern, listed to the left, and visible muscle atrophy on the left peduncle. Due to the rapid decline, surgical stabilization of the vertebral luxation was attempted. The shark was induced with intravenous propofol injection and maintained on MS-222 throughout the procedure. Blood gases and heart rate were monitored while the shark was under anesthesia; mechanical ventilation was required throughout the procedure. Acid-base disturbances were treated as they arose and the shark received fluids, pain medications, and antibiotics intra-operatively. Skin incisions were performed bilaterally at the level of the luxation to access the vertebrae from both sides. Upon exposing the spinal column a visible rupture of the perichondrium was identified. An attempt to reduce the luxation and straighten the spine was made using IM pins and gentle traction. Partial reduction was achieved. Due to prolonged anesthesia and arising hypercoagulability in the shark the decision was made to go forward with internal fixation despite the inability to completely correct the luxation. A seven-hole locking plate was affixed to the vertebral centra bilaterally using locking screws. Platelet rich plasma (harvested from the shark at the onset of the procedure) was injected into the fracture site following surgical reduction. Post-operatively the shark was transported to a medical pool for recovery. Thirty minutes after discontinuing anesthesia the shark started spontaneously ventilating. One hour post-surgery voluntary coordinated swimming was observed. Post-operative swimming was subjectively improved compared to pre-operative swimming. The shark received pain medications and antibiotics for one week following the procedure. She ate one day after surgery and continues to eat on a regular basis. Skin sutures were removed three weeks after surgery; at that time, she received intramuscular parabotulinum toxin A-xvfs injections in the right peduncle to weaken contraction of the muscles and encourage left peduncular muscle usage. Although the shark continues to have pronounced scoliosis swimming remains improved. To the authors’ knowledge this is the first successful spinal surgery performed on a shark. Improved luxation reduction and implant placement using intra-operative fluoroscopy would improve surgical technique. Surgical stabilization of the vertebral centra in this shark appears to have offered sufficient stabilization, allowing the shark to swim more effectively and possibly alleviating pain that may have been present prior to surgery.

Acknowledgements

The authors wish to thank all of their colleagues who offered advice and assistance with this case.

*Presenting author