Abstract

A 51-year-old female bottlenose dolphin presented with tremoring, partial inappetence and microcytic hypochromic anemia, followed by abnormal respiratory character, moderate neutrophilic leukocytosis, and mildly increased liver transaminases. Thoracic and abdominal 2D ultrasound examination revealed pleural and peritoneal effusion, severe alveolar-interstitial syndrome, and pulmonary consolidation with hepatization. Differential diagnoses included infection, neoplasia, and congestive heart failure. Treatment included, as needed, thoracocentesis, abdominocentesis, antimicrobial therapy, diuretics, electrolyte supplementation, gastrointestinal protectants, and fluid therapy. Diuretic therapy was adjusted, as needed, based on presence/absence of effusions and hydration status. All bacterial, fungal, protozoal and viral diagnostics were unremarkable and no evidence of neoplasia was found; therefore congestive heart failure became the presumptive diagnosis. Transthoracic echocardiography revealed marked left atrial and left ventricular dilation with reduced systolic motion, moderate right atrial dilation, and persistent premature closure of the aortic valve, signifying predominantly left-sided volume overload with systolic dysfunction of the left ventricle. The pulmonic valve and AV valves appeared normal. Follow-up echocardiography revealed progressive left ventricular dilation. Due to the animal's deteriorating condition, she was humanely euthanized. Post-mortem findings were consistent with dilated cardiomyopathy and congestive heart failure, characterized grossly by cardiomegaly and pale foci within the right ventricle, and histopathologically by significant cardiac fibrosis, myocyte degeneration, myocyte atrophy, minimal myocardial inflammation and hepatic congestion.

Acknowledgements

The authors thank Dr. Shawn Johnson, Dr. Stephanie Venn-Watson, Dr. Sam Ridgway, Veronica Cendejas, Sacha Stevenson, Risa Daniels, Kevin Carlin, and SSG Eric Alford for their technical support of this case. We also thank the training and management staff at the U.S. Navy Marine Mammal Program for their dedication and support.

* Presenting author