Heart murmur occurs when extra heart vibrations are produced, which lead to abnormal heart sounds. It is often a symptom that your dog may have underlying heart disease. Read on to know more about heart murmur in dogs, its symptoms, and treatment.
Types of Heart Murmurs in Dogs
Heart murmur comes in three types, namely diastolic, systolic, and continuous. The classification is made according to the timing of the murmur. By knowing what type of murmur your dog’s heart has, the vet will have an idea of what caused this condition.
- Diastolic
It occurs when the heart relaxes in between beats.
- DSystolic
It happens every time the heart contracts.
- DContinuous
It is the constant murmur in your dog’s regular heartbeat cycle.
Heart Murmur Grades in Dogs
Another thing that helps the vet in pinpointing the root cause of heart murmur is its configuration. It is also known as qualities and they have four main types, which are:
- Crescendo-decrescendo murmur
The heartbeat tends to go louder and turns quieter. It is linked to heart problems like aortic stenosis and pulmonic stenosis.
- Decrescendo murmur
It begins with strong heartbeats and then they dwindle. This is a common occurrence in dogs with a ventricular septal defect or aortic valve sufficiency.
- Machinery quality
It is also known as a continuous murmur. Dogs suffering from a congenital defect called patent ductus arteriosus (PDA) are prone to experiencing this.
The loudness of the murmur indicates the amount of turbulence happening in your dog’s heart. But it isn’t always precisely linked with how severe the condition is.
Heart Murmur Grades
Grading is done to assess the intensity of your dog’s heart murmur. It may range from grade I to grade VI. The vet will be using a stethoscope to help him hear the heart murmurs and determine its intensity.
- Grade I
This is a light heart murmur that often goes undetected. Grade I murmur is the least serious condition.
- Grade II
It is closely similar to grade I murmur. However, it is more detectable.
- Grade III
A heart murmur with this grade has a high chance of being caused by a serious health problem.
- Grade IV
It is quite loud that it can be heard on both sides of the chest.
- Grade V
The noise of the heart murmur can be easily heard through the stethoscope. It can even be felt by placing a hand on your dog’s chest.
- Grade VI
This is the most severe of all the heart murmurs. It very strong and its vibrations can be felt on the chest wall.
What is an innocent or physiologic heart murmur?
It is a mild heart murmur that usually happens to younger puppies especially if they are large breeds. In the grading scale, it may rank around grade I or II. Typically, this type of heart murmur has no adverse impact on the dogs’ health.
An innocent heart murmur may first appear when they’re around six to eight weeks old. In general, it disappears when they reach between four and five years of age.
Are heart murmurs hereditary in dogs?
A heart murmur can be a hereditary condition in dogs. Many factors can cause this, such as heart defect in family history, age, and breed predisposition. It is observed that middle-aged and older large breed dogs are highly vulnerable to heart murmurs. Below are dog breeds that are prone to developing this condition:
- Boxer
- Cocker spaniel
- Dalmatian
- Dobermann pinscher
- Great Dane
- Irish wolfhound
- Newfoundland
- Portuguese water dog
- Saint Bernard
Is heart murmur fatal in dogs?
It depends on how severe the disease is that caused the heart murmur. In many cases, this ailment is often very treatable. However, if you have an older dog with a heart murmur, be more cautious as most often his condition is quite fragile.
Keep in mind that any dog with a heart murmur needs to get diagnosed and receive proper treatment. A heart murmur caused by pathological heart disease commonly leads to congestive heart failure. If left without medical care, it can prove to be fatal.
What are the causes of heart murmurs in dogs?
Every time there is a change in the flow of blood through the heart, a murmur occurs. There are many causes as to why it happens, including:
1. Due to regurgitation
The four heart valves only allow blood to flow in one direction. When any of these valves become defective and cannot stop backflow, the blood goes through the gaps in the valve with every heartbeat. This results in a heart murmur, which sounds like gushing or squirting.
Diseases that can cause this:
- Myxomatous mitral valve degeneration (MMVD): Defective mitral valve or the tricuspid valve.
- Infective endocarditis: Heart valves are impaired by an infection.
2. Due to narrowed valves
Heart murmur also happens when the valves are abnormally narrowed. This pinches the pump of blood, which leads to an irregular squirt of flow.
Diseases that can cause this:
- Pulmonic stenosis: Injury to the pulmonary valve.
- Subaortic stenosis: Injury to the aortic valve.
3. Due to holes in the heart
The blood flow goes through the holes, thus resulting in a heart murmur.
Diseases that can cause this:
- Ventricular septal defect: This happens when there’s a hole between the left ventricle and right ventricle. It causes the blood to be pushed through that opening when both ventricles pump.
- Patent ductus arteriosus (PDA): There is a hole between the aorta and the pulmonary artery. This causes the blood to flow through the hole.
4. Due to an illness
The thinning of blood can cause heart murmur as it hastens the speed of blood flow. It commonly happens to dogs with anaemia and other sicknesses such as fever.
Heart Murmur in Dogs: Symptoms and Treatment
Symptoms of Heart Murmur in Dogs
Here are the most common signs of a heart murmur in dogs that you need to watch out for:
- Appetite loss
- Weight loss
- Pale gums
- Collapse
- Breathing difficulties
- Exercise intolerance
- Coughing
Diagnosing Heart Murmur in Dogs
The vet will start by using a stethoscope to determine the type and grade of your dog’s murmur. They may also perform additional tests to check if the condition is caused by an underlying health condition. Here are some exams your dog may be required to take:
- Blood test
- Doppler
- Echocardiogram
- Electrocardiogram
- Radiograph
- Ultrasound
How to treat heart murmur in dogs
The treatment for heart murmur in dogs depends on the underlying cause of the condition. If your dog has an innocent heart murmur, he doesn’t require treatment. However, he should be closely monitored to ensure that no heart disease symptoms will arise.
If the diagnosis shows that the heart murmur is caused by another health problem, the treatment will be designed to get rid of this illness. The vet may include a combination of supportive care, special diets, and medication.
Dogs with congenital heart defects such as pulmonic stenosis and patent ductus arteriosus may require surgery.
