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Heart murmurs in dogs can be concerning for pet owners, as they may indicate underlying health issues. In this informative article, we will explore the symptoms and signs of heart murmurs in dogs, discuss their causes, and provide insights into the diagnosis and treatment options available.
Understanding these crucial aspects will help you confidently navigate your dog's health and well-being.
What is a Heart Murmur in Dogs?
A heart murmur is an abnormal sound caused by blood flowing back into the heart through leaky valves. When a veterinarian listens to your dog's heart, they hear two parts of the heartbeat: the opening and closing of the valves. If there's a backflow of blood due to leaky or damaged valves, a different sound called a heart murmur is detected.
Heart murmurs can be identified early in life during puppy wellness checks or later in life as your dog ages.
Breeds commonly affected by heart murmurs include Cavalier King Charles Spaniels, Chihuahuas, Dachshunds, Dobermans, and Boxers.
What Causes Heart Murmurs in Dogs?
Your vet might be able to hear a heart murmur for many reasons. Here are some of the most common causes:
Physiological or ‘Puppy Murmur’
A puppy's blood's thickness or viscosity differs from an adult dog's. This, combined with the fact that the heart is growing rapidly, can lead to turbulent blood flow and a murmur. Puppy murmurs are usually quiet and disappear by six months of age.
These physiological murmurs are innocent puppy murmurs and will not make your puppy unwell. Following up with your veterinarian as your puppy grows up is important to ensure the murmur goes away.
Leaky Heart Valves
Two sets of atrioventricular valves lie between the atria and the ventricles. They prevent blood from flowing back up into the atrium when the ventricle contracts. If they don’t form a good seal, blood leaks through the gaps. This jet stream of blood causes the murmuring sound.
An example of this is Mitral Valve Disease (MVD), which is common in small breed dogs and particularly prominent in Cavalier King Charles Spaniels.
Birth Defects
If the heart and surrounding blood vessels don’t develop properly before birth, this can lead to a heart murmur. These congenital abnormalities could lead to extra blood vessels, a hole in the heart, or a narrowing of a blood vessel. Patent Ductus Arteriosus (PDA) is an example of an additional blood vessel. The ductus arteriosus is a vessel that bypasses the lungs when a puppy is in the womb. When the puppy is born, the vessel should close. However, occasionally it doesn’t.
Another example of a congenital condition is Pulmonic Stenosis, where the pulmonic valve forms a partial obstruction so that the blood cannot easily leave the heart to go to the lungs. These conditions can be severe, and without prompt treatment, can be life-threatening.
Changes in the Size of the Heart
If the heart becomes enlarged, the blood flow becomes more turbulent and less smooth. This can lead to murmurs, although it doesn’t always. Dilated Cardiomyopathy (DCM) in dogs causes heart enlargement and thinning of the muscular walls. This condition is common in Dobermans and Cocker Spaniels, among other breeds, and sadly can be fatal.
It’s important to remember that DCM doesn’t always cause a heart murmur, so predisposed dog breeds should be screened for the condition.
Signs & Symptoms of Heart Murmurs in Dogs
Heart murmurs can be a sign of an underlying condition, such as heart valve disease, congenital heart defects, or dilated cardiomyopathy. Identifying the symptoms of heart murmurs is crucial to the early detection and treatment of any potential cardiac issues.
When the heart murmur is severe, common signs we see in dogs include:
- Abnormal or racing heartbeat
- Difficulty breathing or shortness of breath
- Excessive panting, even when resting
- Coughing, especially at night or after exercise
- Fatigue or weakness
- Fainting or collapsing
- Exercise intolerance
- Blue or gray tinge to the gums (emergency)
- Lack of appetite
- Severe water retention
Should My Pet Be Seen by a Veterinarian?
1. Have you noticed changes in your pet’s appetite?
2. Does your pet have diarrhea or loose stools?
3. Have you noticed changes in your pet’s thirst/water consumption?
4. Is your pet having accidents in the house?
5. Is your pet pacing and unable to settle?
6. Is your pet panting more than usual?
7. Is your pet whining or vocalizing more than usual?
8. Is your pet shaking more than usual?
9. Is your pet hiding or avoiding physical contact more than usual?
10. Is your pet more lethargic and sleeping more than usual?
11. Are you concerned about changes in your pet’s behavior?
12. Is your pet scratching their ears?
13. Is your pet licking their paws more than usual?
14. Does your pet have a rash?
15. Is your pet moving more slowly than usual or having a harder time getting up or down?
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Should My Pet Be Seen by a Veterinarian?
1. Have you noticed changes in your pet’s appetite?
2. Does your pet have diarrhea or loose stools?
3. Have you noticed changes in your pet’s thirst/water consumption?
4. Is your pet having accidents in the house?
5. Is your pet pacing and unable to settle?
6. Is your pet panting more than usual?
7. Is your pet whining or vocalizing more than usual?
8. Is your pet shaking more than usual?
9. Is your pet hiding or avoiding physical contact more than usual?
10. Is your pet more lethargic and sleeping more than usual?
11. Are you concerned about changes in your pet’s behavior?
12. Is your pet scratching their ears?
13. Is your pet licking their paws more than usual?
14. Does your pet have a rash?
15. Is your pet moving more slowly than usual or having a harder time getting up or down?
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Heart Murmur Grades in Dogs
Here's a breakdown, on a scale of one to six, of the different grades indicating the severity of the heart murmur condition in dogs:
Grade 1
Murmurs at this stage are characterized by being very mild, often barely audible. These murmurs are generally considered benign and may not raise significant concern. They typically do not require immediate treatment.
Grade 2
Murmurs of this grade are softer than average and are still categorized as relatively harmless. Immediate treatment might not be necessary, and close monitoring could suffice in most cases.
Grade 3
At this level, heart murmurs become moderate and are more distinctly audible with the assistance of a stethoscope. While they indicate a more noticeable abnormality, not all Grade 3 murmurs require immediate intervention. However, further evaluation is recommended to determine the appropriate course of action.
Grade 4
Progressing further, murmurs become moderate to loud. This is often a sign of a significant abnormality in the heart's function. Veterinary intervention and treatment are typically advised to address the underlying issue and prevent potential complications.
Grade 5
Murmurs at this stage are very loud and can even be heard without the aid of a stethoscope. These murmurs warrant urgent attention from a veterinarian for accurate diagnosis and timely treatment. The heightened intensity suggests a more critical heart concern.
Grade 6
In the most severe grade, Grade 6 murmurs are extremely loud and can be heard even without a stethoscope. This indicates a critical condition that demands immediate medical intervention. Emergency veterinary care is essential to address the severe impact on the dog's cardiovascular health.
How Are Heart Murmurs Diagnosed in Dogs?
Heart murmurs in dogs are first picked up when your veterinarian listens to your dog’s chest with a stethoscope. A heart murmur is then graded on a scale of one to six, one being very mild and six being very severe.
Low-grade heart murmurs may be monitored by your veterinarian with regular checkups every three to six months. The veterinarian will listen to the heart again at this point, and if the heart murmur worsens, then diagnostic tests may be advised.
Diagnostic tests to learn more about your dog’s heart murmurs often start with echocardiography, a heart ultrasound. This is best done by a board-certified veterinary cardiologist if one is available in your area. The cardiologist will take measurements of the heart and look at the flow of blood through the heart. These measurements tell us how advanced your dog’s heart disease is. Medication can be prescribed to help support the heart based on these findings.
Chest X-rays may be taken alongside the echocardiography exam. This helps the veterinarian to see signs of congestive heart failure, such as fluid accumulation in the lungs or enlargement of your dog's heart.
Further tests that may be run include electrocardiograms (ECG) which measure the heart's electrical activity, and blood tests to look for other medical conditions that can be treated to help the heart's overall health.
Treatment for Heart Murmur in Dogs
The treatment for some grades of heart murmurs may be to monitor them if your dog is showing no obvious signs of illness associated with the heart murmur.
If your puppy has a congenital heart abnormality, such as a PDA, veterinary surgery may be needed to fix the problem.
Dogs with heart murmurs related to congestive heart failure need medications to support the heart. These medications help the heart to pump blood around the body and reduce fluid build-up in the lungs. This allows your dog’s overall quality of life. Medications will need to be given daily, and often the doses of medications will need to be increased as your dog’s condition gets more advanced.
Conclusion
A heart murmur can go undetected for many years and cause your dog no issues. With high numbers of dogs suffering from heart disease at some point in their life, it’s worth keeping an eye out for heart disease early on.
Regular vet check-ups, including diagnostic tests like ECG exams, can lead to timely treatments that slow the disease's progression and enhance your dog's quality of life. Ensuring your dog's optimal weight and fitness is also crucial for heart health.
For a comprehensive diagnosis, treatment, or advice on maintaining heart health, book a visit with our BetterVet veterinarians today.
Frequently Asked Questions
Is a heart murmur painful?
A heart murmur in itself is not painful, but the effects of having a severe heart murmur such as pulmonary edema (fluid on the lungs) can be stressful, which is a similar sensation to pain.
When should I worry about my dog having a heart murmur?
A heart murmur doesn’t mean that your dog has heart failure, nor does it mean that they’ll develop heart failure soon. What’s most important is that it is monitored closely by your vet and that you know what symptoms to watch out for.
What are the remedies for dog heart murmurs?
While there is no cure for a heart murmur in dogs, treatment can help manage the symptoms. Depending on the severity, remedies may include a change in diet, exercise restrictions, and medication to manage the underlying condition causing the murmur.
Can my dog still exercise regularly with a heart murmur?
The severity of the heart murmur dictates how much exercise is okay for your dog. For low-grade heart murmurs, exercise can continue as normal. For high-grade heart murmurs and dogs with congestive heart failure, gentle short walks only are advised.
Can a dog live with a heart murmur for a long time?
Dogs' heart murmur prognosis varies. Birth defects may turn fatal, while stable adult murmurs can last years before heart failure. Medications can manage conditions like MVD, providing months to years of companionship.
Can a dog's heart murmur go away?
Yes, some puppy heart murmurs can go away as they grow, but structural murmurs may not resolve on their own.
What can I do at home to help my dog with a heart murmur?
The best thing you can do for your dog at home is to keep its body weight within a normal range. Extra weight carried by your dog puts extra pressure on their joints, heart, and overall health. Talk to your veterinarian about a weight loss diet if you think your dog is overweight.
