Dog Health Problems

A heart murmur in dogs sounds like a very frightening diagnosis but, in reality, they are not uncommon in large breed dogs, especially as dogs get older.  Murmurs can range from being barely heard with a stethoscope to being very loud and causing a vibration you can feel when you touch your dog’s chest.  A puppy with a heart murmur may never have any problems with it and it may go away. Here is some more information about heart murmurs.

Cause

Heart murmurs occur when the blood flow to the heart is disturbed. The blood flow can be disrupted enough to produce the sound associated with a heart murmur.  The blood flow can be disrupted in one of several ways:

• It can be disturbed when there is high blood flow through the heart’s valves, whether the valves are normal or not; the structures can vibrate from the high blood flow.

• There can be disturbances in the blood flow connected with some obstruction in the heart and with the blood that flows out around it.  Or, the blood can be disrupted by flowing forward through valves that are diseased or into a great vessel that is dilated.

• There can be a disruption in the blood flow that is connected to a flow that is regurgitant.  This can be due to a valve that is incompetent or not working properly, to a defect in the wall that separates the right and left sides of the heart or the septum, or to the patent ductus arteriosus.

There are several different kinds of heart murmurs and different diseases and conditions can lead to murmurs in each one.

If your dog has a

diastolic murmur

it could be caused by:

* Aortic and pulmonic valve endocarditis (inflammation of the inner layer of the heart)

* Mitral and tricuspid valve stenosis

Heart murmurs can be

To-and-Fro or continuous murmurs

.  These murmurs can be caused by:

* Aortic stenosis with aortic regurgitation

* Patent ductus arteriosus

* Ventricular septal defect with aortic regurgitation

And, if your dog has a

systolic murmur

the following conditions may have caused the problem:

* Anemia

* Aortic stenosis

* Atrial and ventricular septal defect

* Cardiomyopathy and aortic valve insufficiency

* Dynamic right ventricular outflow obstruction

* Dynamic subaortic stenosis

* Heartworms

* Hyperthyroidism

* Mitral and tricuspid valve dysplasia

* Mitral and tricuspid valve endocarditis (inflammation of the inner part of the heart)

* Mitral and tricuspid valve heart failure

* Pulmonic stenosis

* Systolic anterior mitral motion (SAM)

* Tetralogy of Fallot

Symptoms

The symptoms of a heart murmur can vary, depending on the kind of heart murmur your dog has and what caused the murmur.  Symptoms will also depend on how serious the murmur is and where it is located in the heart. If the murmur is a function of some defect in the heart’s structure your dog may show symptoms of congestive heart disease. These symptoms can include general weakness, coughing, and exercise intolerance.

There is a grading scale for heart murmurs so your vet can discuss with you how serious the murmur is.  Grades of heart murmurs range from Grade I which is almost inaudible to Grade VI which is very loud; your vet can hear it with the stethoscope when it barely touches the chest; it vibrates enough so you can feel it when you touch the dog’s chest.

Heart murmurs can also have different “configurations.”  This refers to the way the murmur behaves and often indicates the cause of the tumor.  A plateau murmur is uniformly loud and can be typical of a regurgitant murmur.  Murmurs that get louder and softer (crescendo-decrescendo) are indicative of ejection murmurs and associated with turbulent forward flow.  Murmurs that start out loud and become softer (decrescendo) can indicate a diastolic murmur.

Diagnosis

Your vet will need to diagnose your dog’s heart murmur.  It may require a complete blood count, x-rays, an echocardiogram, and other tests to identify what kind of heart murmur your dog has.

Treatment

Most dogs are treated as outpatients.  You can take your dog to the vet for treatment and then take him home.  He won’t have to stay overnight. Your vet will need to find the best treatment for your dog depending on the underlying cause of the heart murmur.  If your dog is experiencing congestive heart failure, your vet will need to take some emergency measures.  Otherwise, heart murmurs are treated at home.

If you have a puppy with a a heart murmur that is rated as low grade, it is possible that it will heal itself in a few months and no further treatment will be necessary.  Even adult dogs that show some signs of having a heart murmur do not necessarily get any worse.  In many cases your vet will simply need to check on the murmur every few months to make sure it is not getting any worse.  Many dogs live long, healthy lives with a low grade heart murmur and it doesn’t affect their quality of life.

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