Dog Discoveries

I am Your Dog’s Heart


With Valentine’s Day around the corner, we dedicated this Dog Discovery to the dog’s heart. We often take this organ for granted, but this amazing powerhouse does a remarkable amount of work to keep your dog and his body in good working order. We are talking about one of most miraculous “machines” that’s capable of working non-stop, ticking relentlessly for many years of the dog’s life. While a dog’s heart is built in a similar fashion to the human heart, heart disease affects dogs differently than in people. Let’s take a look at what your dog’s heart has to say.

dog heart diseaseLet Me Introduce Myself!

Hello, it’s your dog’s heart talking! Just like the human heart, I am not very impressive looking. People like to imagine me as a Valentine’s day heart, but I am instead just an egg-shaped muscle of an unappealing red/brownish color that’s housed within the thorax.

More than criticizing my looks though, people should look at me for what I accomplish on a daily basis with no down times. What can I say? I am a workaholic “at heart.”  You think I am exaggerating? Here are some impressive dog heart facts about what I do every single day.

  • On an average day, I pump about 4,000 liters of your dog’s blood.
  • At rest, I beat between 70 to 120 times a minute. That’s more frequent than the human heart which beats an average of 70 to 80 times a minute.
  • I beat roughly 144,000 times per day.
  • I work all day and all night and only rest in those brief split second between beats.

I Transport Bloodheart anatomy

As you may know, I am responsible for moving blood through your dog’s blood vessels. To do so, I am equipped with four chambers, two upper ones known as the left and right atria and two lower ones, known as the right and left ventricles. Here’s a quick review of what I do.

When my right atrium receives blood that’s low in oxygen but high in carbon dioxide (a waste product) from the body, it’s pumped into the right ventricle and then into the pulmonary artery so that the lungs can replenish the blood with oxygen. This oxygen-rich blood then travels through the pulmonary vein and goes back to the heart by entering the left atrium.

Here the blood is then pumped into the left ventricle which forcibly pumps the blood through the entire body through the aorta. This cycle keeps repeating over and over for the rest of your dog’s life.

stethWhen Things Go Wrong

You may be familiar with clogged arteries which are a common cause of heart attacks in humans, but when it comes to dogs, arteriosclerosis and heart attacks are actually quite rare. That doesn’t mean that dogs are free from heart disease though.

A common form of heart disease seen in dogs is heart failure. This happens when my valves or muscles give out and no longer work as they should. When this happens, one side of me may be overloaded with work and I cannot keep up, so I might have to give up and eventually fail.

I don’t fail out of the blue though, it’s usually a process taking months or years. I may give signs of trouble by making affected dogs cough when they’re exercised or excited or right after sleeping.

Affected dogs may appear to get tired more easily and may even faint. These symptoms are proof that I am no longer providing adequate circulation (oxygen for the tissues) to meet the needs of the dog’s body.

Luckily, most vets will notice problems especially if I let out a “murmur” that they’ll hear with the stethoscope. Next, x-rays will show if I am getting too worked out. If I appear enlarged, that’s a sign that I am doing too much. Medications can help me pump more efficiently and help dogs remove excess fluid from the lungs.

The vet may recommend a diet low in sodium so to decrease the buildup of fluids. Hopefully, your dog won’t ever go through all of this, but it’s good to keep this in mind so to recognize early signs of trouble especially as your dog ages.

Two conditions in particular are known for making me fail, degenerative valvular disease (DVD) when my valves fail to seal properly (a condition common in small dog breeds) and dilated cardiomyopathy (DCM), when my heart muscles weaken, (a condition common in large and giant breeds).

About 10 percent of all dogs seen in primary care veterinary practices have some form of heart disease. This percentage continues to grow as dogs get older. Up to 75 percent of senior dogs experience some form of heart disease. ~Drake Center for Veterinary Care

puppy murmursA Word About Murmurs

I  am known to make a typical “lub-dub, lub-dub” sound that your vet is familiar with. The “lub” sound means that the valves controlling the flow of blood from the upper chambers to the lower chambers close, while the “dub” sound means that the valves controlling blood going out of the heart close.

However, at times, when your vet listens to me with a stethoscope, he may hear an extra noise that sort of sounds like water flowing through a hose. What’s that? It’s a murmur. Not always this is a bad thing. It just means that the blood makes a whooshing noise as it flows through me.

Heart murmurs are quite common in puppies. According to VCA Animal Hospital, they’re often found in young, large breed puppies as early as 6 to 8 weeks of age, but they usually go away by time these pups reach 4-5 months of age. These murmurs are usually benign. Only in some cases they’re a sign of a structural problem.


  • Healthy Hearts for Dogs, Heart Facts, retrieved from the web on February 8th, 2016
  • Merck Veterinary Manual: Resting Heart Rates, retrieved from the web on February 8th, 2016
  • Pet Education: Heart Failure (Mitral Valve Insufficiency) in the Dog, by Race Foster, retrieved from the web on February 8th, 2016
  • Heartworm Society: Prevention, Diagnosis, and Management of Heartworm  Infection in Dogs, retrieved from the web on February 8th, 2016
  • Veterinary Team DVM360: How periodontal disease can affect pets’ organs, by Mary L. Berg, BS, RVT, RLATG, VTS (dentistry), retrieved from the web on February 8th, 2016
  • Your Dog’s Heart: Heart Health Tips, retrieved from the web on February 8th, 2016

Photo credits:

Diagram of the human heart, Wikipedia, CC BY-SA 3.0

Adrienne Farricelli
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