Heart Murmurs in Dogs Explained

You hear stories about dogs with big hearts, lovely kind natures and a loyalty to their owners which is second to none. However, a dogs' heart is one of their vital organs and it needs to be kept in tip top condition at all times. Some breeds are prone to suffering from heart conditions and others are born with a heart murmur or other heart problem which is called congenital because the condition is inherited from on or other of the parents.

Congenital murmurs usually first appear when a puppy is still growing in their mother's uterus or very soon after they are born. The condition is as a result of defects in their development. However, most heart murmurs in dogs are what is known as “acquired”, that's to say the condition develops later in their lives. Congenital heart murmurs need to be taken very seriously as they can cause dogs to suffer some very severe symptoms which includes sudden death, a condition caused by aortic stenosis.

The Heart Works as a Pump

The heart is the body's pump and its role is to continuously push blood around the body in all living creatures. There are two sides to a heart, namely the right and the left side. It's the left side that receives oxygenated blood from a dog's lungs and then pumps it out to the body and brain. De-oxygenated blood goes into the right side of the heart and is then pumped into the lungs to be oxygenated.

The right side of the heart is considered as being the low pressure side of things due to the fact the blood entering into it only needs to be pumped a short distance until it arrives back in the heart. The left hand side however, has a much bigger task and is thought of as the high pressure side, which means the left side is always stronger and bigger than the right.

Within the heart, there are four chambers called the left and right atria and the left and right ventricles. Each atrium has valves separating them, with the ventricles having them at each exit point that leads to the lungs. These valves play a crucial role in preventing blood from flowing back to the heart in the wrong direction each time that it pumps any blood through it.

The Sound of a Normal Heartbeat

If you listen to your dogs' heartbeat, you will hear a nice rhythmic “lub-dub” as the valves open and close with each heartbeat. But when the heart is diseased this smooth flow is interrupted and disturbed making it sound more turbulent, often you can barely hear a heartbeat at all. Instead the sound is more a “whoosh-whoosh” noise. Vets listen to a dogs' heart in different places because a murmur can vary depending on just what type of heart disease is causing the condition.

Acquired Heart Disorders Explained

It is more common for a dog to suffer from an acquired heart disorder which can often be as a result of a chronic disease that affected the heart's valves. However, the condition could also be a result of a diseased heart muscle with some dogs suffering from both conditions at the same time. The most common being a thickening of the valves called Endocardiosis. The condition may start early in a dogs' life with just mild signs being present. However, the condition gets progressively worse as dogs get older. The changes may be slow which often means the heart is able to cope with the changes by compensating for them.

Why Dogs Suffer From Heart Disorders

Nobody actually knows why changes in a dog's heart valves happen, but small dogs appear to be more predisposed to suffering from the condition than larger canines. It's the left side of a dogs' heart which is usually damaged but with this said, any of the hearts' valves can be affected.

Another reason a dog may suffer valve problems can be put down to when blood borne infections settle in the lining of the heart causing it to become inflamed. The infection could be a result of another septic infection found somewhere else on their bodies and if it reaches the heart, it usually affects the left side causing a murmur.

What Causes Heart Murmurs in Dogs

When it comes to heart murmurs, there are many reasons why a dog may suffer from the condition. It could be a congenital disorder commonly seen in certain breeds, or it could be acquired later on in a dogs' life. Occasionally the symptoms develop so slowly they go unnoticed. However, if any symptoms are present there are several signs to look out which are listed below:

Left Side Valve Failure

If the valves on the left side fail, vets will grade this in stages with the first being a heart murmur in its mildest form and where symptoms may not be quite so evident. However, dogs will show signs which include:

• A dog may experience breathing difficulties when exercised
• Coughing
• Not wanting to be exercised

As the condition gets worse dogs are at risk of sudden death, but with this said the rate a which the condition gets more serious can be very slow, taking years for the disease to become apparent, and even the more severe symptoms may go unnoticed.

Right Side Valve Failure

If it is the right side of the heart that's affected, it would mean that there's an accumulation of fluids in the dogs' abdomen which gives them a pot-bellied appearance. If the spleen and liver are enlarged, the pressure on the diaphragm caused by the extra fluid may cause a dog to be breathless all of the time.

Conclusion

If you are concerned about your dog and are aware the breed may be predisposed to any sort of heart condition, you should discuss any symptoms with your vet as soon as you notice them. The vet will be able to advise you and do certain tests to ensure your dogs' heart is okay and in good condition or whether there is a heart murmur that needs investigating, Regular health checks are always a good idea as dogs get older because if they do have an acquired heart condition, the vet will be able to pick up on it straight away and then recommend the best treatment.