Use of Serial Percutaneous Ethanol Injections and Partial Hepatectomy for the Successful Management of a Hepatocellular Carcinoma in an Asian Small-Clawed Otter (Amblonyx cinereusa)
A 10-yr-old, 3.6-kg sexually intact female Asian small-clawed otter was observed to have abdominal distention. Upon further examination under general anesthesia, a large 6x8x8 cm centralized mass associated with the liver and ascites were identified with abdominal ultrasound. A liver biopsy confirmed hepatic neoplasia. Contrast-enhanced magnetic resonance imaging (MRI) using gadoversetamide (OptiMARK, Tyco Healthcare/Mallinckrodt, St. Louis, MO, USA) at 0.14 mmol/kg was performed to delineate the margins of the tumor. During exploratory surgery, the mass was considered inoperable. Therefore, palliative treatments for hepatic neoplasia were investigated, such as radio-frequency ablation (RFA), chemoembolization, and chemical ablation.5,6
In humans, percutaneous ethanol injection (PEI) is a safe and reliable method for reducing and eliminating focal hepatic tumors, while preserving surrounding hepatic tissue.1,4 Ethyl alcohol causes necrosis of hepatocytes, thereby reducing the size of a hepatocellular mass.3 Ethanol is dosed by calculated tumor volume (HxWxDx0.52) to a maximum of 20 ml.
Five serial PEI treatments using ultrasound guidance were performed on the otter under general anesthesia. Post-procedural monitoring included standard CBC, serum chemistries, serum ethanol, and bile acids. Mild ethanol toxicity consisting of dysrhythmias and hypothermia were observed during two treatments.2 A follow-up contrast-enhanced MRI was performed to evaluate therapeutic effect. With adequate tumor necrosis, a partial hepatectomy was successfully performed by a liver-transplant specialist from University of California San Diego Medical Center. The otter showed post-procedural dermal pigmentation change, but continues to show no tumor recurrence and remains in good health.
The SeaWorld veterinarians would like to thank the animal training staff for their care and assistance with Ethel during these procedures.
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