A 12 year-old female bottlenose dolphin (Tursiops truncatus) with a chronic history of regurgitation presented for subtle changes in behavior, including increased regurgitation and occasional disinterest in training sessions during the last trimester of pregnancy. Examination was unremarkable except that she had lost 5 kg from her previous weight. Diagnostics revealed leukopenia, increased erythrocyte sedimentation rate (ESR) and increased white blood cells on cytological examination of a gastric wash. The animal initially improved following treatment with cephalexin (30 mg/kg PO BID x 7 d) and ranitidine (2 mg/kg PO BID x 30 d).
One month after evaluation, the animal presented for partial anorexia, abnormal behavior, bloody discharge from her blow hole, vaginal discharge and abdominal crunching consistent with preterm labor. Examination revealed bloody discharge from the blow hole, vaginal discharge, and a non-viable fetus. White blood cell count showed a left shift with bands, and an azotemia was noted on the biochemical analysis. The retained fetus was removed via manual extraction after no progression of labor after 48 hrs and the dam was started on enrofloxacin (5 mg/kg PO BID x 10 d) and Clavamox (11 mg/kg PO BID X 10 d). The dam continued to show abnormal behavior including floating at the surface, partial anorexia, decreased activity and discharge from the blow hole. Ceftriaxone (20 mg/kg IM once followed by 4 days of SID intravenous administration) was started as the animal's condition began to decline. Based on culture and sensitivity results from the hemorrhagic blowhole discharge, oral azithromycin (3.5 mg/kg PO SID x 14 d) was initiated in conjunction with itraconazole (4.5 mg/kg PO SID x 21 d, then 2.5 mg/kg SID X 30 d), followed by oral cefpodoxime (5 mg/kg PO SID x 14 d) over several weeks.
The animal appeared to be steadily improving over 12 weeks until bloody discharge from her blowhole returned. Bronchoscopy revealed hemorrhagic discharge from the right main stem bronchus. A 6.5 x 5 cm fluid filled abscess in the right caudal ventral lung lobe was identified with subsequent ultrasound examination. The animal's condition declined following restraint and diagnostic procedures and she was started on ticarcillin (20 mg/kg IM once), given ceftriaxone (20 mg/kg IV SID x 4 d) and maintained on Clavamox (8.5 mg/kg PO x 10 d), after which she showed gradual improvement.
The animal underwent a series of three thoracic CT scans during the course of her illness. The initial scan (10 days after identifying the abscess via ultrasound) still showed a well delineated but smaller fluid filled abscess, surrounding consolidated lung and moderate pneumothorax (from the FNA of the abscess) in the right thorax. The second scan five weeks later showed that the pneumothorax had resolved and the abscess no longer contained fluid. The affected area was half the initial size (3 x 1 cm) and appeared localized and consolidated. The third CT scan was performed seven months after initial presentation and four months after the abscess was diagnosed (via ultrasound). There was still a small area of consolidation at the site of the previous abscess as well as adhesions between the lung and thoracic wall in that area. The extent of the affected area affected was decreased in size and considered minimal at this point. A fourth CT scan was performed opportunistically three years after her presentation to assess long term changes from this bout of respiratory illness. Minor residual scarring in the right ventral lung lobe was all that remained from the initial lesion.
Aggressive medical management and advanced diagnostics were instrumental in diagnosing and treating the pulmonary abscess and respiratory disease in this bottlenose dolphin. Computed tomography was extremely helpful in monitoring the animal's response to therapy and determining her prognosis, and should be considered as a useful diagnostic aid with other cases of respiratory disease in cetaceans.
The authors wish to thank the entire Veterinary Services and Seven Seas team at Brookfield Zoo for their assistance, expertise and time with this challenging case as well as Dr. Chris Dold from Sea World, Orlando for his assistance.