C2 and MDCK cells were cultured with recombinant human TRAIL. Apoptosis was assessed using a Caspase 3 and 7 chemiluminescence assay and flow cytometry following Annexin V:FITC labelling. Cell metabolism was assessed using a colorimetric MTT-based assay. C2 cells demonstrated greater sensitivity to TRAIL-induced apoptosis compared to MDCK cells by all assessment methods. The dog genome assembly was searched for orthologs of TRAIL and its receptors using published sequences from other species for reference. Although a canine ortholog for TRAIL was identified, only one TRAIL receptor ortholog (TNFRSF11B) could be found. C2, but not MDCK, cells expressed mRNA for TNFRSF11B, detected by RT-PCR. In other species, TNFRSF11B is a decoy receptor, as even though it has a death domain it is secreted due to its lack of a transmembrane domain. The effect of TRAIL on the C2 cell line suggests that this cytokine might be suitable for treatment of mast cell tumors in dogs.