BACKGROUND: Doxorubicin (DOX) can cause cumulative cardiotoxicity in dogs, but the incidence of clinical cardiotoxicity in dogs receiving DOX has not been determined. HYPOTHESIS/OBJECTIVES: To determine if the duration of DOX infusion influences the incidence of cardiotoxicity, to characterize the incidence of clinical cardiotoxicity in dogs during or after DOX chemotherapy, and to identify any risk factors associated with cardiotoxicity. ANIMALS: Four-hundred ninety-four dogs that received at least 1 dose of DOX for the treatment of cancer. METHODS: Retrospective study of dogs that received DOX from 2006 to 2015. RESULTS: Of 494 dogs, 20 (4.0%) developed clinical cardiotoxicity. The duration of DOX infusion was not significantly associated with clinical cardiotoxicity, whereas a higher cumulative dose of DOX, higher body weight, decreases in fractional shortening after 5 doses of DOX, and development of ventricular premature contractions were significantly associated with clinical cardiotoxicity. High-risk breeds for developing dilated cardiomyopathy had an incidence of 15.4%, whereas low-risk breeds had an incidence of 3.0%. CONCLUSIONS AND CLINICAL IMPORTANCE: Although the duration of DOX infusion did not influence the incidence of cardiotoxicity, premature contractions and decreases in fractional shortening should raise concern for the development of clinical cardiotoxicity. Overall, the incidence of clinical DOX-induced cardiotoxicity is low, but Boxers and other breeds at high risk for dilated cardiomyopathy may be at an increased risk.