abstract

Respiratory disease is one of the most common causes of morbidity observed in cetaceans under human care. Presentations may appear as would be expected for an infectious bronchitis/bronchiolitis or chronic obstructive pulmonary disease, and clinical signs may range from simple anorexia and mild chuffing to severe dyspnea. Occasionally, more chronic cases may be completely asymptomatic. Tests utilized in the diagnosis of upper and lower airway disease often include complete blood count, serum chemistries, cytology, culture and sensitivity, thoracic radiographs and ultrasound examination, and bronchoscopy. Results obtained from these different modalities have directed the administration of oral and parenteral antimicrobials, as well as the use of oral corticosteroids. Oral bronchodilators have been prescribed infrequently. However, the incomplete resolution of clinical signs, either due to improper dosage or failure to deliver medications directly to the source of pathology, as well as the potential for negative systemic side effects, have prompted the need to develop a more effective and efficient means of nebulization therapy for dolphins with respiratory disease.

There are not any "off-the-shelf" dolphin inhalers currently available, nor are there other veterinary products that would allow us to accomplish the goal of providing nebulized drug to a dolphin patient. Previously described nebulized drug delivery systems have been built from plastic bottles and other containers that could accommodate a large bolus of nebulized drug.¹ These systems were frequently large and awkward, and while potentially effective, required the help of multiple support staff to hold both the animal and the inhaler system throughout the procedure.

There were intrinsic and extrinsic challenges to overcome in the development of a useful nebulized drug delivery system. Those intrinsic to the patient included the unique cetacean respiratory anatomy and mechanics, and the animal's behavioral tendency to resist breathing through a covered blowhole or against any form of resistance. Extrinsic challenges included producing and containing a large volume of nebulized drug that would not be displaced upon exhalation, and building a system that under ideal conditions could be used by one person working with the patient.

With these challenges in mind, we came up with a novel design for a low profile, light-weight, hand-held, nebulized drug delivery system. The system is low resistance, with segregated exhalation and inhalation chambers, so it can handle the large-volume, rapid air exchange generated when a dolphin ventilates. The system is built around new, commercially available, compact nebulizer technology². These nebulizers are battery powered and can generate large volumes of nebulized drug in a short period of time. The system can be applied to critically ill patients that are supported or restrained, but is small and light enough to be used "pool-side", with animals breathing through it under behavioral control. The system is molded from clear plastic and new units can be made quickly as new cases develop.

So far we have used the system in the management of two cases over the past year. We have determined that the system delivers vaporized drug into the airways by endoscopically observing the trachea and mainstem bronchi during its use. However, more work needs to be done to determine appropriate case definitions and effective drug and treatment protocols to realize the system's full potential as a therapeutic tool. The Dolphin Inhaler is available for interested clinicians or institutions, and can be obtained through Taylor's Pharmacy in Winter Park, Florida.

References

1.  Whitaker BR, Hadfield CA, Clayton LA, Neiffer D, Stamper A. 2005. Mycobacterium abscessus infection in an Atlantic bottlenose dolphin (Tursiops truncatus). Proceedings, 36th International Association for Aquatic Animal Medicine Conference, 49-51.

2.  Omron MicroAir Electronic Nebulizer with V.M.T. (NE-U22V). http://www.omronhealthcare.com/