Abstract

A 29-year-old female Atlantic bottlenose dolphin living in a natural saltwater lagoon presented with chronic abnormal breathing, consisting mainly of a prolonged tidal respiratory cycle. Computed tomography and bronchoscopy demonstrated focal severe stenoses of the right mainstem bronchus (RMB) and the tracheal bronchus near each origin. The pulmonary parenchyma and remaining bronchi were unremarkable. Bronchoscopic brushings and biopsy samples were non-diagnostic. The stenoses were suspected to be the result of a previous fungal infection, as reported in the literature.^1,2 Balloon bronchoplasty of the right mainstem bronchial stricture was performed in an attempt to increase the luminal diameter and improve respiration.

The dolphin was placed on a foam pad in a controlled environment and sedated with intramuscular midazolam and meperidine. A 3-lead ECG was placed and monitored throughout the procedure. Bronchoscopy was performed using a 6-mm diameter, 102-cm pediatric gastroscope (EG-1870; Pentax Medical Corp., Montvale, NJ) as described previously.^3,4 After passing the gastroscope into the trachea, a guidewire (0.035 cm) was introduced through the instrument channel. The scope was then removed and reinserted, leaving the guidewire in place. Serial dilations of the stenotic RMB were performed under direct visualization via the adjacent gastroscope using increasing diameter high-pressure balloons passed over the guidewire. Ultimately, an 18-mm balloon was dilated to 8 atm, demonstrating significant improvement in luminal diameter. A mucosal tear was then noted on the lateral and medial wall of the RMB, and no further dilation was attempted. Thoracic radiographs were obtained immediately and did not show any evidence of pneumothorax, pneumomediastinum, or pleural effusion. Reversal medications (flumazenil and naloxone) were administered intramuscularly, and the dolphin was returned to the lagoon where she recovered uneventfully. Follow-up bronchoscopy at one month, six months, and one year post procedure showed sustained increased diameter of the treated area with no narrowing or strictures associated with healing. Tidal respiratory cycle length decreased immediately post procedure and has remained significantly lower for approximately two years, at this writing.

This is the first time balloon bronchoplasty has been performed in a dolphin. The procedure is not without risk. Detailed study of dolphin airway and thoracic vascular anatomy is advised prior to repeated attempts. Further study and collaboration with pulmonologists are needed to determine if balloon bronchoplasty is an acceptable therapeutic option for dolphins with airway stenosis.

Acknowledgements

The authors would like to thank the entire staff of Island Dolphin Care and Dolphins Plus in Key Largo, FL, for their support and Jeffrey Solomon, MD, MBA, Infiniti Medical, Menlo Park, CA, for supplying the balloon and guidewire instruments.

* Presenting author

Literature Cited

1.  Kinsel MJ BM. Chronic fungal tracheitis with stenosis in an Atlantic bottlenose dolphin (Tursiops truncatus). In: Proceedings of the International Association for Aquatic Animal Medicine Conference; 2005:41–43.

2.  Brudek-Wells RL TF, Rotstein D. Tracheal zygomycosis presenting as stridor and partial upper airway obstruction in a pantropical spotted dolphin (Stenella attenuata). In: Proceedings of the International Association for Aquatic Animal Medicine Conference, Las Vegas, NV; 2011.

3.  Reidarson TH, Harrell JH, Rinaldi MG, McBain J. Bronchoscopic and serologic diagnosis of Aspergillus fumigatus pulmonary infection in a bottlenose dolphin (Tursiops truncatus). Journal of Zoo and Wildlife Medicine. 1998;29(4):451–455.

4.  Tsang KW, Kinoshita R, Rouke N, Yuen Q, Hu W, Lam WK. Bronchoscopy of cetaceans. Journal of Wildlife Diseases. 2002;38(1):224–227.