In both human and veterinary oncology patients, it is well-established that antineoplastic medications, especially those given intravenously, can be found at temporarily high concentrations in the bodily excretions of patients after treatment (urine, saliva, feces). However, only recently have tears been evaluated as a bodily fluid that could excrete potentially dangerous levels of chemotherapeutic medications. There have been limited reports of antineoplastic drug-related ocular toxicity in veterinary patients and none in which tear concentrations were assessed. The purpose of this study is to investigate the tear concentrations and associated ocular side effects of antineoplastic drugs in cancer-bearing dogs without any pre-existing eye disease.