Anatomy of a Canine Heart Vs. a Human Heart

By Catherine Troiano

When comparing your heart to that of your canine companion, his heart is similar to yours in form and identical in function. There are differences, however, when it comes to the rates at which these two hearts beat, and the commonly diagnosed cardiac diseases of humans and dogs.

Similar Structures

The canine heart and the human heart each have four chambers. The upper chambers are the right and left atria, and the lower chambers are the right and left ventricles. Leading into the right atrium are the two largest veins in the body, the venae cavea. Leading out of the right ventricle is the pulmonary artery, and the pulmonary veins lead blood into the left atrium.

The largest artery in the body, the aorta, directs blood out of the left ventricle. A series of valves keeps the blood flowing in a uniform and orderly direction to carry out the function of blood circulation.

Among the subtle structural differences between a human heart and a canine heart is the number of pulmonary veins. The human heart has four to five pulmonary veins. A canine heart can have anywhere from four to eight. Other differences include the positioning of venae cavea and slight differences in the sizes and shapes of the atrial appendages.

Same Physiological Function

Both the canine heart and the human heart carry out the same function of pumping oxygenated blood to the rest of the body to nourish cells and promote their functions. The heart, the arteries and the veins make up the closed circulatory system that dogs and humans possess. In a closed circulatory system, blood travels through a loop. Blood enters the right atrium of the heart through the two venae cavea. From there, the blood enters the right ventricle and is pumped through the pulmonary artery to the lungs, where the blood absorbs oxygen and releases carbon dioxide. The oxygenated blood then enters the heart's left atrium via the pulmonary veins. The blood then fills the left ventricle, from where it is pumped out through the aorta to distribute throughout the rest of the body.

Differences In Heart Rate

One of the notable differences between a canine heart and that of his human family member lies in the rates at which the two hearts beat. At rest, a human heart's normal pulse rate ranges from 60 to 100 beats per minute. An adult dog's resting heart rate ranges between 60 to 160 beats per minute. Larger breeds will have heart rates that fall on the lower end of this range, while toy breeds and young puppies exhibit the highest rates.

Differences In Cardiac Diseases

Although heart disease is a leading cause of death in humans, the same cannot be said of dogs. Humans and dogs both can develop cardiac problems, however. While humans must be concerned about coronary artery disease, this condition does not tend to afflict dogs. Instead, dogs can develop other cardiac problems that can all result in congestive heart failure/understanding-heart-failure.pdf?sfvrsn=0). Three of such canine conditions are:

  • Mitral valve disease, a condition in which a valve thickens and fails to close securely, allowing blood to back up into the atrium of the heart.
  • Dilated cardiomyopathy, which is a weakening of the heart muscle.
  • Pericardial effusion, a condition in which fluid accumulates within the pericardial sac that surrounds the heart.