Potential of Fenbendazole in Canine Cancer: Pet Owner Experiences

Benzimidazole drugs such as fenbendazole (FBZ) exhibit anti-cancer effects on various cancer cell lines in vitro, but the benefit in companion animals diagnosed with cancer has yet to be established. Despite a lack of clinical evidence, in recent years anecdotal reports of owners using FBZ as part of their pet’s cancer treatment have increased. The objective of this study was to provide descriptive data on FBZ administration behaviors and the perceived effect of FBZ treatment on quality of life (QOL) and survival outcome for dogs with cancer. The study survey was voluntarily completed by 87 owners who were invited to participate through an online social media platform. Variables evaluated included demographics, cancer type, recommended and pursued treatments, FBZ usage, perceived effects on QOL, and survival outcome. Osteosarcoma, lymphoma, and mast cell tumor were the most common cancer types reported. FBZ was well tolerated in the study population, with GI signs (10.3%) being the most common side effect reported by owners. When FBZ was administered (alone or with standard-of-care cancer treatments), 41.4% of owners reported their dogs experienced longer survival times (ST) than the estimated prognosis. Owners also perceived improved QOL in their dogs while using FBZ. Perceived improvements in QOL and survival outcomes for dogs given FBZ underscores the need for an organized, systemic evaluation of FBZ as an adjuvant cancer treatment in veterinary medicine.