Abstract

An approximately 1-month-old male harbor seal (Phoca vitulina) was presented to Vancouver Aquarium's Marine Mammal Rescue Centre with evidence of prior trauma. The animal sustained superficial injuries to all limbs and had multiple facial lacerations. There was unilateral facial swelling of the ventral right mandibular region. He was stabilized and initially treated with crystalloid fluids, dextrose, ceftriaxone (20 mg/kg, IV), ceftiofur (7 mg/kg, SQ), and dexamethasone (0.25 mg/kg, IV). He was then treated with a 7-day course of ciprofloxacin (12.75 mg/kg, PO).

When the animal was stable, he was sedated with midazolam (0.15 mg/kg, IV) and butorphanol (0.15 mg/kg, IV) for radiographs. A closed, complete fracture of the right caudal mandible was diagnosed and the fracture site had smooth edges. No instability was appreciated on palpation, so medical management was elected. Three weeks after radiographs were taken, the animal had purulent discharge from the right side of his mouth. Repeat radiographs revealed a boney sequestrum at the fracture site and a draining tract was noted externally. There was exposed necrotic bone within the oral cavity that was removed along with the #405 tooth. Enrofloxacin (5 mg/kg, PO) and tramadol (2 mg/kg, PO) were prescribed.

One month following that procedure, the animal was again sedated for repeat radiographs. At this time, there was minimal range of motion of the temporomandibular joint and a large amount of callus had formed around the fracture site. Another necrotic sequestrum was removed, but it was determined that open surgical fixation was required.

A ventral approach to the mandible was achieved and the boney callus was debrided. Removal of the callus resulted in full range of motion of the temporomandibular joint. A canine trabecular bone powder and equine lamellar cortical bone matrix were soaked in autogenous highly concentrated platelet-rich plasma (hcPRP) prior to being introduced at the fracture site. Intraosseous wire was placed during the procedure. A platelet-rich fibrin (PRF) clot was placed over the wire, bone grafts, and fracture. Prior to closure, the remaining hcPRP was introduced at the fracture site. Following skin closure, platelet-poor plasma (PPP) was applied to the incision. The animal was prescribed carprofen (2.2 mg/kg, PO), tramadol (2 mg/kg, PO), and ciprofloxacin (10 mg/kg, PO) postoperatively.

Jaw mobility was decreased in the initial perioperative period, but the animal was able to apprehend and consume small fish. His clinical demeanor was utilized to assess postoperative progress. Computed tomography (CT) imaging was performed at 2 and 8 weeks following surgery to monitor bone healing. There have been no postoperative complications following xenografts and autogenous hcPRP, PRF, and PPP.

The use of PRP to aide in fracture healing relies on the activation of platelet-derived growth factors.¹ Although there are reports to suggest that PRP has no effect on healing,^2,3 the combination of xenograft, hcPRP, PRF, and PPP in this harbor seal appears to have had a positive effect on healing of a previously non-union fracture.

Acknowledgements

The authors thank Chellan Robinson, Jenelle Hebert, Sion Cahoon, Kit Thornton, Krista Leeb, and Andrew Celmainis in addition to all of the volunteers at the Vancouver Aquarium's Marine Mammal Rescue Centre for their help and support while caring for this patient.

* Presenting author
⁺ Student presenter

Literature Cited

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2.  Choi BH, Im CJ, Huh JY, Suh JJ, Lee SH. Effect of platelet-rich plasma on bone regeneration in autogenous bone graft. Int J Oral Maxillofac Surg. 2004;33:56–59.

3.  Jensen TB, Rahbek O, Overgaard S, Soballe K. No effect of platelet-rich plasma with frozen or processed bone allograft around noncemented implants. Int Orthop. 2005;29:67–72.