Ask the Vet: Why Do Dogs With Heart Failure Cough?
Dr. Ivana Crnec
When dogs with failure cough, dog owners are often worried about it, and seek out information on how they can help their canine companions cough less and make them more comfortable. Is there a medication that can help control coughing in dogs with heart problems? Veterinarian Dr. Ivana Crnec clears up many doubts provides answers.
Heart Disease Versus Heart Failure in Dogs
The heart is a muscular, double-sided pump that beats with a marvelous efficiency. Sadly, a variety of conditions, both inherited and acquired, can affect the heart’s ability to perform its vital function.
With that being said, it should be noted that contrary to popular belief, the terms heart disease and heart failure cannot be used interchangeably. But what is the difference between heart disease and heart failure?
Simply put, a heart disease is any abnormal condition affecting the heart. A dog may have a heart disease, but show no signs of illness and never need medical treatment.
Sometimes though, the heart disease may lead to heart failure – a condition in which the heart cannot keep up with its workload of pumping blood to the lungs and around the rest of the body.
Heart failure always has noticeable effects, such as reduced tolerance of exercise, coughing, or even collapse.
Heart Failure in Dogs
Heart failure can occur due to a plethora of reasons. However, the most common underlying cause is chronic valve disease. In chronic valve disease, for unknown reasons, the flaps of the valves between the atria (upper heart chambers) and ventricles (lower heart chambers) can become thickened and distorted until their edges no longer meet when the valves shut.
A heart affected by such condition that reduces its pumping efficiency can usually compensate for months or even years. It usually does so by increasing in size. However, the compensation capacity is not unlimited.
Eventually, the underlying disease leads to congestive heart failure, in which blood becomes backed up in the veins. This buildup, in turn, forces fluid out of the circulation into the body tissues, in the lungs and elsewhere.
Based on the exact disease process, heart failure in dogs can affect the right side of the heart, the left side of the heart or both sides. The general weakness and respiratory signs occur as a consequence to:
Fluid retention – in this case, the failure is due to congestion and popularly known as backward failure
Pump failure – in this case, the failure is due to low cardiac output and popularly known as forward failure.
Signs of Heart Failure in Dogs
Coughing is not always linked with heart issues. In fact, more often than not, coughing is caused by a primary lung or airway disease.
When indicative of heart problems, coughing can often be caused by airway compression due to an enlarged heart. Ultimately, coughing can be linked with heart failure.
Generally speaking, the cough can be linked with heart failure if it is described as chronic, harsh and if it ends with a gag.
To determine the type of cough and its link with heart issues, it is advisable to consider the following questions:
How long have the respiratory signs, or more precisely speaking the cough been present? How are the dog’s activity level and appetite? What is the cough like (mild or harsh, acute or chronic, ending with or without a gag)?
Based on these answers, you vet should be able to determine whether your dog's cough is associated with heart failure.
"Coughing is frequently reported in dogs with cardiac disease. Enlargement of the left atrium can compress the mainstem bronchi and stimulate cough that is commonly observed in dogs with mitral valve disease. In dogs with congestive heart failure, edema fills the airways and pulmonary venous distention stimulates juxtapulmonary receptors. When the receptors are stimulated, reflex bronchoconstriction and increased mucus secretion occur, resulting in a cough."~Frontiers in Veterinary Science
At The Vet's Office
A vet diagnoses heart failure when the typical signs are present and are consistent with known heart disease. Commonly performed diagnostic procedures include chest and abdominal x-rays, ECG, and echocardiography.
Dogs with heart disease, but no signs of heart failure should be treated normally and given a full exercise routine. When the first signs of heart failure develop, dogs should be treated with a combination of ACE (angiotensin-converting enzyme) inhibitors and diuretics such as furosemide.
The ACE inhibitors widen the blood vessels thus reducing the workload on the heart. Diuretics are also known as water pills, because they make your dog urinate more, clears fluid congestion from the lungs and veins.
Other medications that act on the heart and circulation, such as digitalis, calcium channel blockers, beta blockers, and anti-arrhythmic drugs, may also be used in some cases. Nitroglycerine (a drug that widens blood vessels) may be recommended in some advanced cases.
Dietary treatment for heart failure remains controversial. Excess salt in the diet should be avoided but the benefit if low-salt diet is, as yet, not proven.
Essential fatty acid (EFA) supplements may be of value for some dogs with heart failure. Antioxidants, selenium and vitamin E may also be beneficial in certain cases. Routine, daily light exercise is beneficial as long as it does not cause the dog to cough, tire easily or breathing rapidly.
"Diuretics and vasodilators are indicated for a patient with congestive heart failure."~Frontiers in Veterinary Science, Coughing in Small Animal Patients