Abstract
Watercraft-related trauma is the greatest cause of morbidity and mortality for the Florida manatee (Trichechus manatus latirostris). Watercraft can injure manatees in two ways: sharp trauma (lacerations from propellers) and blunt trauma (impact force with hull).1 These injuries are typically along the dorsal aspect of the manatee due to their normal position in the water column. Pneumothorax is a common sequela to blunt force trauma, though pneumothorax can also arise spontaneously in manatees.
Due to unique anatomy with a complete mediastinum and two separate hemithoraces, manatees with pneumothorax usually present positively buoyant and listing to one side in the water column. On exam they are frequently asymmetrical with a “D-shape.” Dyspnea and tachypnea are often absent, even in very severe pneumothorax. Definitive diagnosis can be accomplished with radiographs and/or ultrasound.
A manatee ‘wetsuit’ is often utilized to help normalize buoyancy for pneumothorax cases. Treatment can be conservative with just supportive care2 or involve thoracocentesis under sedation. CT scans can elucidate underlying injury much better than plain radiographs, but this modality is limited by size and weight of larger animals. For refractory pneumothorax cases, thoracoscopy and positive pressure ventilation has resulted in resolution for two manatees. Pleurodesis with autogenous blood has been attempted without success so far, but with refinement of the technique may become a viable therapeutic option in the future.
Acknowledgements
The authors wish to thank the entire SeaWorld Orlando Veterinary Services and Rescue Team for hard work and dedication to these cases. We also extend sincere appreciation to Dr. Faith Hughes, DVM, DACVS from Peterson and Smith Hospital and Radiology Team from Florida Hospital at Celebration for their assistance with several of our persistent pneumothorax cases.
* Presenting author
Literature Cited
1. U.S. Fish and Wildlife Service. 2001. Florida manatee recovery plan (Trichechus manatus latirostris). 3rd rev. Atlanta, GA: U.S. Fish and Wildlife Service.
2. Gerlach TJ, et al. 2013. Conservative management of pneumothorax and pneumoperitoneum in two Florida manatees (Trichechus manatus latirostris). J Zoo Wildl Med. 44(4):996–1001.