Cardiac or heart disease can take many forms, and have many causes (etiologies).
Congenital is when a problem is present at birth, usually as a result of an anatomical anomaly. Examples are patent ductus arteriosus which occurs when there is a shunt around the major arteries that supply the heart that does not close at birth. This is usually detected by a veterinarian at the pet’s first visit and is manifested by a very loud and pronounced murmur. Treatment is the surgical ligation of the shunt, reestablishing proper blood flow dynamics to the heart.
The other congenital anomalies are septal defects of the heart. The septum is the wall that separates the 4 chambers of the heart. If a hole is present between the chambers, blood leaks through and causes the other chambers of the heart to enlarge due to an increased blood volume. Eventually heart failure occurs. The murmurs present in these cases are not as pronounced as the patent ductus arteriosus. Surgical correction is much more difficult because it involves in open heart surgery versus ligating vessels outside the heart.
Valvular defects can be congenital or acquired. Acquired cases usually occur in older patients, usually smaller breeds. Predisposing factors include chronic dental disease that seeds the valves with bacteria setting up placque deposits, not allowing the valves to close properly, causing an audible murmur, and eventually causing other chambers of the heart to enlarge.
Cardiomyopathies are syndromes where the the heart muscle is affected and the heart gets larger. Certain breeds are predisposed, ie Doberman Pinschers, Boxers, and Great Danes.
Heartworm disease can cause permanent damage to the heart. The severity of the infection and length of time with the disease before treatment, will contribute to the severity of damage to the heart.
Diagnosis is usually made during a routine physical exam. Ideally the pet is not showing any clinical signs and a murmur is detected. As heart disease progresses, the pet owner may notice coughing, especially at night and early morning. Exercise intolerance, weight loss, lethargy, and bloating may be seen as the disease progresses into heart failure. We are very aggressive in promoting diagnostic tests when a cardiac abnormality is detected. We can do chest radiographs, electro cardiograms, blood pressures, and ideally, we refer to a cardiologist for an echocardiogram.
Cardiac disease, as in most disease processes, responds best when diagnosed early. There are many drugs available that help manage and slow down the progression of the disease. We do not ascribe to the commonly held suggestion that “ just watch him/her. If he/she starts coughing, or has exercise intolerance, we will pursue it further.” What you are then telling a client is we will wait until their pet is in congestive heart failure before we treat. If we had received the same suggestion from one of our physicians, I am sure most of us would seek a second opinion. Pets can lead long and productive lives with heart disease if they are diagnosed early and monitored routinely.