OBJECTIVE To report the outcome of doxorubicin‐based chemotherapy as the sole treatment for dogs with echocardiographically identified right atrial masses and pericardial effusion. METHODS A retrospective study of case records of dogs with right atrial masses treated with doxorubicin. Dogs were excluded from the study if they had any type of surgery performed such as pericardiectomy or right atrial mass resection, or if their chemotherapy protocol did not include doxorubicin. The data collected included signalment, history, physical examination findings, diagnostic test results and long‐term survival. RESULTS Dogs with right atrial masses and pericardial effusion that received doxorubicin‐based chemotherapy alone had a median survival of 139 · 5 days (range 2 to 302 days). Chemotherapy side effects were frequent but mild. CLINICAL SIGNIFICANCE Doxorubicin‐based chemotherapy alone appears to be a viable treatment option for dogs with echocardiographically identified right atrial masses and pericardial effusion.

Acquired tricuspid valve stenosis (TVS) is a rare complication of endocardial pacing lead implantation in humans that has only been described once previously in the veterinary literature in a dog with excessive lead redundancy. A 12 yr old terrier presented with right-sided congestive heart failure 6 mo after implantation of a second ventricular endocardial pacing lead. The second lead was placed due to malfunction of the first lead, which demonstrated abnormally low impedance. Transthoracic echocardiography identified hyperechoic tissue associated with the pacing leads as they crossed the tricuspid valve annulus as well as a stenotic tricuspid inflow pattern via spectral Doppler interrogation. Medical management was ultimately unsuccessful and the dog was euthanized 6 wk after TVS was diagnosed. The authors report the first canine case of acquired TVS associated with two ventricular endocardial pacing leads.