Canine Cardiac and Heart-Base Tumors: When a Mass Affects Circulation

Weakness, exercise intolerance, fainting or collapse, rapid or labored breathing, cough, reduced appetite, abdominal swelling, pale gums, or an abnormal rhythm may occur. Some masses are found incidentally.

Lesions may involve the right atrium, heart base, pericardium, valves, myocardium, or adjacent mediastinum. Location often guides the differential and whether a procedure is feasible.

Emergency stabilization may precede diagnosis. Echocardiography is central for a heart mass or pericardial effusion; chest imaging, CT, ECG, bloodwork, fluid analysis, or selected tissue sampling may add information. Fluid cytology can be nondiagnostic.

Collapse, fainting, labored breathing, very pale or blue gums, a distended abdomen with weakness, or inability to settle is an emergency. Transport instructions should come from an emergency clinic when possible.

Pericardial drainage may be lifesaving but does not treat the underlying tumor. Surgery, pericardiectomy, radiation, systemic therapy, monitoring, or palliative care may be discussed according to location, diagnosis, recurrence of fluid, and patient stability.

When the clinic recommends it, record sleeping respiratory rate, episodes of weakness or collapse, appetite, gum color, abdominal size, activity tolerance, and medication effects. Do not exercise a dog with unexplained fainting.