Abstract

Stranded porpoises and dolphins are rehabilitated at oceanariums following illness or injury from a variety of causes such as infections, toxins, trauma from net entanglement, boat strikes, or other fisheries interactions. Respiratory disease has been recognized as the leading cause of death among captive dolphins for the last two decades². Early detection of cetacean respiratory disease is difficult but essential for its successful treatment³.

Bronchoscopy is a promising technique for the early detection of respiratory illness in cetaceans and has been successfully used in the bottlenose dolphin^3,4. However, since bronchial airway sizes differ among cetaceans of different ages and species, more information is needed regarding types of bronchoscopes appropriate for diverse cetacean patients. Refinement of cetacean bronchoscopy also requires development of a nomenclature system to facilitate description of the anatomic site at which lesions occur. This allows precise identification and monitoring of respiratory lesions and accurate communications between veterinarians.

The goal of this research was to adapt the dog and horse nomenclature system devised by Amis, McKiernanl and Sweenys to the harbor porpoise (Phocoena phocoena). Silastic and air dried models of the bronchial tree were made to illustrate the anatomy, devise the nomenclature and describe the most appropriate bronchoscopes.

Five harbor porpoise lungs were removed from their carcasses. The endobronchial anatomy was observed and filmed through a 9.5mm GIF-100 Olympus video Gastroscope inserted at the larynx. From 4 inflated, air-dried lung specimens, a flexible plastic mold of the bronchial airways was made. The permanent mold was made using Dow Corning Silastic E with 40% radio-opaque barium. A dorsoventral radiograph was taken of the lung containing the Silastic E/barium mold. The lung tissue surrounding the cast was dissolved by placing the lung in Clorox and measurements (position, length and diameter) of the plastic cast were taken with a 6-dial. caliper. The branching patterns of lobar and segmental bronchi were identified through combined use of videoendoscopy, radiographs, and study of Silastic molds. Following identification of bronchial anatomy in these specimens, the Amis and McKiernan nomenclature was adapted to the harbor porpoise lung in the same way Sweenys adapted this nomenclature to the horse.

In the nomenclature system developed by Amis and McKiernan for the canine, the lobar bronchi are named according to the order of their emergence from the primary bronchi. Additionally, the side of the primary bronchus from which the lobar bronchi originate is incorporated into the nomenclature. The harbor porpoise lung has 3 major primary bronchi while the domestic dog has two. The porpoise possesses a right tracheal bronchus and the right and left primary bronchus are common to both species. The nomenclature of Amis and McKiernan was readily applied to the porpoise lung. In 4 of the 5 lungs studied, the lobar bronchi originated from the principal bronchi in the same order and in the same approximate anatomic location. Both wild cetaceans and those in captivity will benefit from the development of lung models and standardized bronchoscopic techniques for research and description of respiratory disease. Since most bronchoscopy of cetaceans is performed with little or no anesthesia, the duration of the examination must be minimized. Plastic casts of porpoise lungs allow the bronchoscopist to study and anticipate bronchoscopic findings, facilitating efficient exams. Development of a standardized nomenclature for cetaceans will promote consistency in the description of respiratory illness, fulfilling the need for standardized reproducible criteria for diagnosis and treatments.

Acknowledgements

This work was supported by a fellowship from the Geraldine R. Dodge Foundation, Frontiers for Veterinary Medicine. The authors would like to thank the New England Aquarium for providing us with the Harbor Porpoises, Dr. Larry Kleine, Dr. David Sherman, Mrs. Sheila Moffat, Dr. Richard M. Jakowski, Ms. Gillian Sanders, Mr. Bob Brown, Mr. Brian Delgiudice, Dr. Tecumseh Fitch, Mr. Evan Mead and Tufts University Wildlife Clinic for their expertise and assistance during the course of this project. This presentation was supported by Abbott Diagnostic Laboratory Animal Health Division and Waltham USA Pet Foods.

References

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2.  Dunn JL. Bacterial and mycotic diseases of cetaceans and pinnipeds. In Marine Mammal Medicine, Dierauf, L., Ed. CRC Press, Boca Raton, Florida, 1990, pp.73-87

3.  Jeraj KP, Sweeney JC. Blowhole cytology to diagnose early respiratory tract disease in bottlenose dolphins. International Association of Aquatic Animal Medicine (IAAAM) Proceedings, 27th Annual Conference, Tennessee. 1996:27:112

4.  Reidarson TH, McBain J, Harrell JH. The use of bronchoscopy and fungal serology to diagnose Aspergillus fumigatus lung infection in bottlenose dolphin (Tursiops truncatus). International Association of Aquatic Animal Medicine (IAAAM) Proceedings, 27th Annual Conference, Tennessee. 1996:27:34

5.  Sweeny CR, Weiher J, Baez JL, Lindborg SR. Bronchoscopy of the horse. Am J Vet Res 1992:53:10:19531956