HEPATOCELLULAR NEOPLASMS IN CAPTIVE FENNEC FOXES ( VULPES ZERDA)

Hepatocellular carcinomas (HCC) are the most common primary hepatic neoplasm of dogs and occur at a high prevalence in captive fennec foxes ( Vulpes zerda). Of 54 captive fennec fox submissions to Northwest ZooPath, 15 (28%) foxes were diagnosed with HCC. This group consisted of nine males, four females, and two foxes of unspecified gender. Affected foxes ranged in age from 8 to 13 yr (mean 10.3 yr). Clinical signs included weight loss/inappetence ( n = 2), lethargy/weakness/ataxia ( n = 3), and seizures-shaking/tremors ( n = 4). Hematologic abnormalities included elevated liver enzymes ( n = 5), hypoglycemia ( n = 3), anemia ( n = 2), and elevated renal analytes ( n = 2). In eight cases, a palpable or visible hepatic mass was identified. The gross morphologic patterns had been recorded or photodocumented for 13 HCC; these were reclassified according to the human World Health Organization (WHO) classification of hepatic neoplasms as massive ( n = 8), nodular ( n = 4), and diffuse ( n = 1). The histomorphologic pattern according to the WHO classification of hepatic neoplasms was determined for all 15 HCC with the majority of HCC ( n = 12) being classified as mixed and two HCC as trabecular and one as compact. Trabecular ( n = 11), pseudoacinar ( n = 7), compact ( n = 6), and scirrhous ( n = 1) patterns were observed in the 12 mixed HCC. All HCC were well-differentiated, but seven cases had moderate anisokaryosis. In seven HCC, a significant portion of neoplastic cells were identified as clear cells and six cases had a pelioid pattern. Necrosis was detected in six HCC, affecting between 5-40% of the neoplastic cells. As no metastases were noted at time of diagnosis, based on morphologic similarities to canine HCC, complete surgical removal of the affected liver lobe is suspected to be associated with a favorable prognosis.