One of the most common causes of morbidity and mortality in bottlenose dolphins is pulmonary disease. When pulmonary disease is suspected, ultrasound examination has been used in an attempt to determine severity of disease. However pulmonary ultrasound has serious limitations, and unless pleural effusion or peripheral pulmonary lesions are present, significant disease can go undetected. Traditional thoracic radiographs have also presented numerous challenges, and obtaining a valuable set of images in a timely manner has proven to be frustrating for many marine mammal veterinarians. The introduction of digital radiography has dramatically changed our ability to obtain a rapid, accurate assessment of pulmonary health in bottlenose dolphins.
In 2005, we began a population survey of Navy animals to develop baseline thoracic digital radiographs on individual animals and search for signs of underlying pulmonary disease. In addition, we have examined known cases of pulmonary disease and used radiographs to determine severity and response to therapy. We have also used digital radiography to rule-in or rule-out pulmonary involvement in animals with nonspecific clinical signs. For these radiographic procedures, animals were transported a short distance to our veterinary clinic. Digital radiographs were obtained with an Eklin Medical Imaging EDR5 RapidStudy® Portable Digital Radiography System (Santa Clara, CA) and either an Acoma Mobile X-Ray System MBA-200 (Wheeling, IL) or a Poskom Diagnostic X-ray Unit PXP-40HF (Goyang, Korea). The Eklin system incorporated a large format Canon® 14" x 17" direct capture digital x-ray sensor panel. Digital radiography produced high-quality images in seconds that could be viewed immediately and then stored and managed as Diagnostic Imaging and Communications in Medicine (DICOM) images on a Picture and Archiving Communication System (PACS). DICOM images were then viewed with EFilm Workstation 2.0.1 software (Milwaukee, WI), evaluated by the clinical team, and then shared electronically with an Army veterinary radiologist for formal interpretation. The PACS system facilitated management of all DICOM images generated by our facility, including CT, MRI, and nuclear medicine images.
Three case examples demonstrated the usefulness of DR for our program. The first case was an adult female bottlenose dolphin with chronic fungal pneumonia that became dyspneic when removed from the water. Digital radiographs were ideal for minimizing time out of the water and obtaining high-quality images during treatment. The second case was a young (~ 4 month old) female bottlenose dolphin that had been treated for low-grade pneumonia. DR was used to assess her response to treatment. Due to this animal's young age, we opted not to transport her to the clinic but instead performed the radiographs on the floating walkway next to her ocean enclosure. Special precautions were taken when operating X-ray equipment adjacent to seawater. The third case was an adult male bottlenose dolphin with no outward clinical signs. DR was performed as part of his annual health exam and showed no evidence of underlying pulmonary disease. Based on its usefulness, DR has been incorporated into our routine approach to both diagnostic workups and our preventive medicine program.
Dr. Dold's present address is SeaWorld Orlando, 7007 SeaWorld Drive, Orlando, FL 32821. The authors thank the Navy Marine Mammal Program training, veterinary technician, and management staff for supporting these efforts, specifically Veronica Cendejas and SGT Eric Alford.