Elisa M. Mazzaferro, MS, DVM, PhD

Depending on the primary cause and severity of the cardiac disease, clinical signs can vary from patient to patient and are by no means pathognomonic for cardiovascular disease. Clinical signs may include weakness and exercise intolerance, cough, lethargy, inappetence, vomiting, diarrhea, tachypnea, respiratory distress, syncope, or collapse. CHF is often presumptively diagnosed based on a patient's primary presenting complaints, signalment, a thorough history, and physical examination findings.

Important concepts to remember in managing any patient with CHF are to minimize patient stress and to do no harm. This discussion focuses on patients with CHF that present in cardiogenic shock and require emergency lifesaving treatment.

It's important to differentiate patients with cardiogenic shock from patients with hypovolemic shock because the treatment for cardiogenic shock (e.g. diuretics) can exacerbate hypovolemic shock. A careful physical examination is essential in diagnosing and treating a patient with CHF.^1-4 If the animal is in severe distress, it should be placed in an oxygen cage or receive flow-by oxygen supplementation. The restraint for physical examination and diagnostic testing can sometimes push the most stressed patients over the edge. So initially observe the patient from afar. What is the respiratory rate and effort? Is fluid coming from the nares or mouth? Does the abdomen look distended? Is the patient able to stand or is it weak?

Next, approach the patient, and perform a systematic examination from head to toe. Are the mucous membranes pale pink or do they appear cyanotic? Is the capillary refill time prolonged? Look carefully at the thoracic inlet and jugular groove. Is there jugular venous distention or a jugular pulse? Is the heart difficult to hear during auscultation and are the heart sounds muffled? Is a murmur or a dysrhythmia present? Simultaneously palpate the inguinal region for a femoral pulse. Are the pulses strong or weak? Are they synchronous or asynchronous with the heart rate? Are the pulses absent in a patient with acute onset of respiratory distress and hindlimb or forelimb paralysis? Auscultate all lung fields to detect pulmonary crackles or wheezes. Palpate the abdomen to identify hepatomegaly and a fluid wave. Also palpate the distal extremities. Are they warm, or do they feel cold because of poor peripheral circulation? Finally, perform a rectal examination to check for bloody feces.

Patients with fulminant pulmonary edema from left-sided CHF may have blood-tinged fluid coming from the nares and mouth and have concomitant pulmonary crackles and a rapid restrictive respiratory pattern. A cardiac murmur is often present in cases of severe mitral insufficiency, but in some patients, the heart may be difficult to hear beyond harsh pulmonary crackles. Cardiac dysrhythmias may or may not be present. Weak pulses, pale mucous membranes, depressed mentation, prolonged capillary refill time, and cool peripheral extremities may indicate low output cardiac failure. Pulses may be absent in patients with severe low output failure or arterial embolism. Jugular venous distention and jugular pulses may be visible in patients with right-sided heart failure. Heart sounds may be muffled to absent in patients with pleural or pericardial effusion. Hepatomegaly and a fluid wave may be present on abdominal palpation in cases of right-sided heart failure. On rectal examination, hematochezia may be present secondary to poor mesenteric perfusion and splanchnic congestion from poor cardiac output.

DIAGNOSTIC TESTS

Several diagnostic tests may be indicated when evaluating patients for CHF, including electrocardiography, radiography, echocardiography, blood pressure measurement, and oxygen saturation measurement.