The coughing older dog: lung or heart (Proceedings)
In geriatric dogs, heart and lung diseases are not uncommon with cough being the most common clinical sign. Differentiating between lung and heart as the cause of the cough is often not difficult, though in some cases both diseases are present. Using history, physical examination and radiography an accurate diagnosis can often be made. In some cases echo is needed as well, especially in breeds where interpretation can be a challenge (i.e. bulldogs).
History and Physical Examination
Multiple historical complaints can occur with heart disease, though almost invariably cough is the most common. Initially cough is caused by compression of the mainstem bronchi by the enlarging left atrium. As failure develops, edema will develop as well leading to cough. Other signs that are common with CHF include weakness, exercise intolerance, weight loss, dyspnea, cyanosis and syncope. With right sided heart failure ascites can develop as well.Since endocardiosis is the most common cause of heart failure in older dogs, a murmur should almost always be heard in geriatric patients with heart problems that are causing cough. If the heart is difficult to auscult disorders such as obesity, pleural effusion, pneumothorax and pericardial effusion need to be considered. Often dogs with CHF will have evidence of muscle mass loss, especially if the problem has been chronic.
Imaging studies are vital to definitively document heart failure in a dog with appropriate signs. Good quality radiographs are vital to achieve this goal. Both lateral and ventro-dorsal (or dorso-ventral) radiographs are needed to be able to assess all chambers of the heart accurately. Radiographs also allow identification of any pulmonary abnormalities that may be present (chronic lower airway disease, metastatic disease, etc.). In almost all cases, the left atrium has to be enlarged for a dog with heart disease to be coughing. In order to accurately assess the left atrium good radiographs are vital since such factors as obesity, rotation on the lateral image and an expiratory view will make the heart appear large and the lungs dense.
Ultrasound is not vital in most geriatric dogs with CHF. Usually the history, physical examination and radiographic findings are sufficient to establish this diagnosis. Ultrasound is very useful however in those cases where radiographic findings are equivocal, where endocarditis is suspected or in early cases of dilated cardiomyopathy.