Induction of Hepatocellular Carcinoma in Conventional Domestic Swine Using N-Diethylnitrosamine and Phenobarbital

Abstract

Purpose: Large animal models are still used in many studies because of their likeness to humans. It has not been documented that regular-sized conventional farm-breed pigs, generally bred for meat production, can be used to generate hepatocellular carcinoma (HCC) animal models. The goal of this study was to investigate how N-diethylnitrosamine (DENA) and phenobarbital (PB) together can generate HCC in ordinary farmed pigs.
Materials and Methods: Conventional domestic swine (Sus scrofa domesticus) were used. DENA 15 mg/kg was intraperitoneally injected weekly for 12 weeks, while PB tablets (4 mg/kg) were also administered through food for 16 weeks. Blood testing and ultrasonography evaluation were performed to monitor the progress. Subsequently, computed tomography was conducted in cases with suspected nodules, followed by histopathological examination to confirm the diagnosis.
Results: Ten swine (seven males, three females; age: 2 months; weight: 9– 15 kg) were included in the study and followed up for 25 months; nine were experimental, and one was control for ethical considerations. The maximum weight of animals during this study reached 162– 228 kg. The weight gain seen in the intervention swine was predominantly lower than that documented in the control. The laboratory analysis revealed no notable abnormalities in liver function markers but did demonstrate statistically significant changes in urea (p = 0.028) and creatinine (p = 0.003) levels. Ultrasonography and computed tomography showed multiple liver nodules with characteristics resembling HCC. Serial imaging screening and more extended observations revealed that all animals eventually developed tumors. Histopathological confirmation at 15– 22 weeks post-induction revealed that all intervened swine developed multiple nodules of well-differentiated HCC and some with hepatic angiosarcoma.
Conclusion: This study successfully generated HCC in conventional domestic swine with a DENA and PB combination. This investigation required at least 15 months to develop tumors. This model will be beneficial for future investigations of HCC in large animals.

Keywords: carcinogenesis, large animal model, hepatocellular carcinoma, domestic swine, DENA induction