Structure and Function of the Cardiovascular System in Dogs

Below is information about the structure and function of the canine heart and blood vessel system. We will tell you about the general structure of the cardiovascular system, how it works in dogs, common diseases, and common diagnostic tests performed in dogs to evaluate the heart and blood vessels.

What Is the Cardiovascular System?

The cardiovascular system (or circulatory system) is the system responsible for circulating blood throughout the dog’s body. It consists of the heart and blood vessels, namely arteries, veins and capillaries.

Where Is the Cardiovascular System Located in Dogs?

The heart is located in the chest between the right and left lungs and is contained in a very thin sac called the pericardial sac. The heart extends approximately from the 3rd to the 6th rib of the dog.

Blood vessels form a conduit system throughout the body and carry blood to all organs, tissues and cells.

What Is the General Structure of the Cardiovascular System?

The heart is the central organ that contracts rhythmically to pump blood continuously through the blood vessels. The heart consists of four chambers:

Arteries are strong, muscular blood vessels that carry oxygen-rich blood from the heart to various parts of the body. The wall of an artery consists of an outer coat (tunica adventitia), a middle coat (tunica media), and an inner coat (tunica intima). Small blood vessels that branch off the arteries are called arterioles.

Veins are thin blood vessels that carry blood from various parts of the body or organs back towards the heart. Like arteries, veins have three coats, but the coats are not as thick. Because of their thin walls, veins are very compliant, and their volume and size vary with blood pressure. Veins also contain valves, which allow blood flow in only one direction, towards the heart. The valves stop blood from flowing backward towards the organs. Small blood vessels that lead from the capillaries to the larger veins are called venules.

Capillaries are the smallest of all blood vessels. Capillaries are so small, that in many instances only a few red blood cells can pass through the center of the capillary at a time. Capillaries usually lie between the arterioles and venules. Capillary walls act as a membrane that allows various substances to travel between the blood and the tissues. These substances include oxygen, carbon dioxide, water, electrolytes (e.g. sodium, potassium), nutrients, and minerals. The capillaries are the site of the greatest exchange of material between the blood and the tissues of the body.

What Are the Functions of the Canine Cardiovascular System?

The circulatory system transports to the tissues and organs of the body the oxygen, nutritive substances, immune substances, hormones and chemicals necessary for normal function and activities. It also carries away waste products and carbon dioxide, helps to regulate body temperature, and helps to maintain normal water and electrolyte balance.

What Are the Common Diseases of the Cardiovascular System in Dogs?

What Types of Diagnostic Tests Are Used to Evaluate the Cardiovascular System?