Problems of the Heart: An Overview into Canine Heart Disease

Dog owners know only so well that dogs have the purest of hearts – and that is why it is such a tragic irony to have to fear your pooch from getting ill from disorders associated with the cardiovascular system.

There are several types of heart diseases, and while some heart problems come from a young age, many arise as your dog ages as the heart muscle loses tone or the valves weaken. Such diseases impair heart function which is to pump oxygenated blood throughout the body and receive deoxygenated blood to deliver it to the lungs for oxygenation. Clinical signs associated with heart disease may also arise, making daily living harder or more uncomfortable for your canine companion.

The good news is that most canine heart diseases are avoidable and preventable with proper nutrition, weight management, and optimal physical activity. In this overview we will talk about the common types of heart diseases in dogs, how they happen, and what loving dog owners can do to address or prevent them.

Congenital Disease

Congenital heart diseases are abnormalities that are present with the pup at birth and may be caused by a combination of various risk factors associated to heredity, environment, toxins, and nutrition and medications of the mother.

Although rare, there are many types of congenital heart disease among dogs, and most are associated with anatomical defects. Examples are patent ductus arteriosus, persistent right aortic arch, ventricular or atrial septal defect, pulmonic or aortic stenosis, and tetralogy of Fallot.

It’s all a mouthful of highfalutin medical terms, but at the end of the day they all mean an abnormality in the heart that prevents it from pumping blood properly to the poor pup.

Congenital heart diseases can be diagnosed by a veterinarian from physical examination of your pup and using diagnostic tools such as electrocardiography and ultrasonography of the heart or echocardiogram.

Pups with congenital heart defects most likely need to undergo surgery, or there is a high chance, sadly, that they won’t live very long. Because there is some genetic predilection to it, dog owners are advised not to breed dogs come from breeding lines with known congenital heart problems.

Myocardial Disease

The myocardium is the cardiac muscle, or the smooth muscle that makes up the walls of the heart. This type of muscle tissue is only found in the heart and it holds a very special function – it is what keeps the heart pumping blood throughout the body 24/7.

As your dog grows older, the heart muscle may not be as strong as it was before. The muscle may thin out and may become too weak to handle the blood pressure. As a result, the heart ventricles widen, causing an enlarged heart.

This condition is known as dilated cardiomyopathy or DCM. It more commonly affects male dogs of large breeds such as Great Danes, Boxers, Doberman Pinschers, Saint Bernards, and Irish Wolfhounds. Sadly, Doberman Pinschers are found to survive the disease shorter than other breeds.

DCM is diagnosed by doing an echocardiogram, and as treatment your vet will typically prescribe several medicines aimed at improving the regulation of blood pressure, helping the heart with its pumping, and dilating blood vessels to help compensate for the weaker heart pumping.

Another myocardial disease is hypertrophic cardiomyopathy or HCM. It is less common in dogs and cases are more observed in cats. As opposed to the heart muscle thinning out in DCM, in HCM the myocardium has thickened, causing the heart chamber to narrow.

This leads to decreased blood flow, compromising heart function and elevating heart rate. While some dogs (and mostly cats) that get HCM do not show clinical signs, some others can have difficulty breathing, weakness, and even fainting episodes.

Similar to DCM, the veterinarian can also confirm HCM through tests like echocardiogram, auscultation for heart murmurs, x-ray, and electrocardiography.


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Valvular Disease

The canine heart has four valves, and all are important in ensuring that blood flows in the heart in one direction and back flow does not occur. Unfortunately, and similar to the myocardium, as dogs age and the heart valves continue to do their work, heart valves can get worn out, especially the mitral valve in the left side of the heart where the blood pressure is stronger.

As the mitral valve does not close properly, blood traveling to the left ventricle leaks back into the left atrium, creating a mitral regurgitation.

Over time, fluid accumulates in the atrium, causing the heart to enlarge. The buildup of fluid and pressure can eventually cause the lungs to also accumulate with fluid, which can be very dangerous.

While myocardial disease predominantly affects larger breeds, degenerative valvular disease (DVD), on the other hand, is more common in small breeds of dogs. As the disease is a progressive condition that develops over time, dogs don’t typically show symptoms until the fluid buildup occurs and affects the lungs.

At the clinic, the veterinarian will run a series of tests to determine the presence of DVD. They will also auscultate your dog’s heart to check if they hear heart murmurs, which is a common sign of valvular abnormalities. The disease is irreversible, and so your vet will prescribe medications to help with the problems caused by DVD, such as diuretics to decrease the fluid buildup in the body, vasodilators to help lower blood pressure, and positive inotropes to strengthen the pumping of the heart.

The earlier it is diagnosed, the more chances for your dog to live a longer, more comfortable life.

Parasitic Disease

Heartworm disease is a serious and fatal parasitic disease in dogs caused by the helminth Dirofilaria immitis.

Canine heartworm disease is present throughout the United States and the rest of the world, and it is more prevalent in areas where there is a high population of mosquitoes, as they serve as the intermediate host that spreads the parasite by feeding on the blood of dogs.

Although the disease is treatable, treatment approaches can be difficult, expensive, and may have side effects especially when the condition has advanced.

The good news, however, is that preventive medications are available to help protect your dog against heartworm. Heartworm preventives are safe and inexpensive, and you can easily discuss options with your vet. After all, prevention, whenever available, is a small price to pay for the health and safety of your pooch.

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