As little is known about the efficacy of cytotoxic and small molecule inhibitors in canine lung cancer, the purpose of this study was to characterize the activity of currently used chemotherapeutic agents and the small molecule inhibitors, torceranib phosphate, crizotinib and STA-1474 and the effects of HSP90 inhibition on the mRNA expression of relevant kinases and HSP90 client proteins in two canine lung cancer cell lines. This evidence concerns the gene HSP90AA1 and lung carcinoma.