Dec. 29.2021 | Updated: January 4, 2022

What Is a Heart Murmur in Dogs: Its Types, Stages, Signs, Reasons & Treatment

heart murmur in older dogs

You don’t need to have a special medical background to notice dangerous symptoms in your pet. It is quite realistic to assume heart murmur in dogs and most of the time the owners are right. However, do not panic right away, because there are different types of these noises and some of them are really dangerous, while others require minimal effort to heal. Let’s find out everything about this so that you can react in time.

What Is a Heart Murmur in Dogs?

A dog’s heart pumps blood through its body. When this blood flow is disrupted, an audible noise called a murmur occurs, which can be distinguished from a normal heartbeat with a stethoscope. The veterinarian breaks down noise into several categories.

Types and Grades of Heart Murmurs in Dogs

There are three types of murmurs:

  • Systolic occurs when the heart muscle contracts;
  • Diastolic is when the heart muscle relaxes between beats;
  • Constant occurs during your dog’s normal heartbeat cycle.

Knowing canine heart murmur grades and types can help to start proper treatment. The intensity of it is assessed on a 6-point grade (from 1 to 6):

  • 1 – very soft localized noise, detected after a few minutes of listening;
  • 2 – soft noise, small area of ​​localization, detected immediately;
  • 3 – the noise of moderate-intensity, detected immediately;
  • 4 – a moderate/loud murmur is usually auscultated on both sides of the chest. There is no precocial vibration;
  • 5 – loud noise, vibration, large listening area;
  • 6 – a very loud noise, detected immediately when the stethoscope is brought to the chest.

What Causes Heart Murmur in Dogs?

A canine heart murmur can occur for several reasons. Further diagnostics are usually required to find the real cause, especially of a higher grade murmur.

  • Some heart murmurs are caused by structural heart problems. Let us remind you that the dog’s heart has four chambers: the right atrium, the right ventricle, the left atrium, and the left ventricle. In a normally functioning heart, oxygen-depleted blood from the veins enters the right atrium and is pumped into the right ventricle. The blood passes through the pulmonary artery, is saturated with oxygen, and enters the left ventricle. Oxygenated blood is pumped through the left atrium and then out into the body through the arteries. Valves between each chamber and blood vessels keep the blood flowing in the right direction. Structural problems, such as leaking valves or holes in the heart chamber, can cause impaired blood flow. This creates turbulence that can be heard as a heart murmur. Some structural abnormalities are present at birth, while others can develop later in life. Below are some of the more well-known abnormalities in the structure of the heart:
    • Mitral valve disease;
    • Tricuspid valve disease;
  • Certain problems in the body can affect blood flow through the heart, even if the heart itself is functioning normally
    • Anemia;
    • Hyperthyroidism;
    • Infections.
  • Physiological heart murmurs are benign, meaning they are not caused by a disease process. These noises are usually mild to moderate (grade I-II). If your veterinarian detects mild to severe heart murmur in dogs, and the absence of other signs, your veterinarian may want to simply check your dog periodically to monitor the murmur rather than immediately recommending further diagnosis.

Symptoms of Heart Murmur in Dogs

Pets can show signs of heart murmur in dogs or other signs of illness.

  • Cough;
  • Lethargy;
  • Exercise intolerance;
  • Weakness;
  • Shortness of breath or difficulty breathing
  • Pale gums;
  • Bloating (bloating);
  • Collapse episodes.

If you notice one or more of these or other signs, be sure to seek advice from your veterinarian. Examination and further diagnostic tests may be required.

How to Treat Heart Murmur in Dogs?

canine heart murmur

Since a heart murmur is not a disease in itself, but a symptom of a potential medical condition, treatment will depend on the underlying cause. Therefore, the first step is to diagnose the cause of the murmur. After receiving a detailed medical history from you regarding your dog, your veterinarian would conduct a thorough physical examination of your pet. Several diagnostic tests are needed to assess heart function and overall health. For heart murmur in older dogs, your veterinarian would recommend a biochemistry, complete blood count, and urinalysis to assess organ health and cell count. Chest x-rays (X-rays) are required to look at the size of the heart and details of the heart and lungs. Specialized heart tests may be needed to better examine the heart. Your chief veterinarian may refer you to your veterinary cardiologist for this examination. An electrocardiogram (EKG or EKG) measures the electrical activity of the heart. This is displayed as signals that can be analyzed for deviations. An echocardiogram is an ultrasound scan of the heart that shows the heartbeat as well as blood flow through the heart. The sonography can measure the chambers and valves of the heart and look for pathological patterns of blood flow. Once the diagnosis is made, let’s find out dog heart murmur treatment recommendations. Some heart abnormalities require surgery. Other conditions can be treated with medication. Dogs would need regular follow-up visits to the veterinarian and/or cardiologist to monitor response to treatment and monitor disease progression. Be sure to follow your veterinarian’s recommendations for treatment and follow-up.

How Does a Heart Murmur Affect a Dog?

Heart murmur stages in dogs may be too serious, but they are not a reason to panic all day. Many causes are treatable and, in some cases, can be corrected on their own. However, in more severe cases, especially in older dogs, the prognosis may be more guarded, but remember that hearing a heart murmur is the first step towards resolving the disease. There are many possible reasons, and the distinction between types and grades can be confusing, especially if you do not have a medical background. If you have other questions about your dog’s heart murmur, check them with your veterinarian.

FAQ: Heart Murmur

heart murmur stages in dogs

Find answers to other frequently asked questions below that we haven’t discussed yet.

Are Heart Murmurs Common in Dogs?

Puppies, especially of large breeds, very often have innocent heart murmurs during their rapid growth. Murmurs may first appear at 6-8 weeks of age, and puppies with innocent heart murmurs may suffer around 4-5 months.

What Does a Heart Murmur Sound Like in a Dog?

When your veterinarian listens to your dog’s heart, they hear the typical heartbeat sound. These sounds represent the closing of the heart valves. When you hear a heart murmur, it means that your veterinarian may hear “whooshing”.

How Serious Is a Heart Murmur in a Dog?

It depends on the type and stage. For example, at stages 1 and 2 it is not dangerous, but higher – there may be consequences.

Can a Dog’s Heart Murmur Go Away?

Many causes of heart murmur are treatable and, in some cases, can be corrected on their own. However, in more severe cases, especially in older dogs, the prognosis may be more guarded, but remember that hearing a heart murmur is the first step towards resolving the disease. So heart murmur in dogs is characterized by sound, by which you can recognize its type and stage. And after diagnosis, prescribe treatment. Doesn’t sound so easy, does it? Keep in mind, however, that not starting treatment on time can trigger several associated health problems. Therefore, be more attentive to your pet and do not forget about regular visits to the veterinarian. It can help to prevent some health issues!

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