Cardiac Conditions
(5min read)
A heart murmur is an abnormal sound that a veterinarian hears when listening to the heart through a stethoscope. It can be an indication of heart disease, so other diagnostic tests are needed to investigate further. To diagnose the cause of a murmur, your veterinarian may recommend tests such as blood tests, chest radiographs (x-rays), and echocardiograms (ultrasound of the heart).
What is a Heart Murmur?
When listening to a pet’s heart through a stethoscope, a veterinarian normally hears two sounds, a “lub” and a “dub”, which are the sounds of the heart valves closing as blood circulates through the heart. An additional “whooshing” sound, known as a heart murmur, is usually associated with a disturbance of the smooth blood flow through the heart.
Veterinarians rank the intensity or loudness of a heart murmur in grades from one to six, with one being barely audible and six being the loudest. A heart murmur is not always a cause for concern, but it may be an indication of a heart problem. Depending on your pet’s condition, the veterinarian may want to perform additional diagnostic tests to determine the cause of the murmur.
What causes a heart murmur?
Heart murmurs are caused by any number of conditions that can create turbulence in the flow of blood through the heart. In dogs, common causes for heart murmurs include:
- Heart valve deficiencies or blockages
- Defects in the heart walls
- Dilated cardiomyopathy (weakening of the heart muscle walls)
- Heartworm disease
- Endocarditis (infection of heart valves)
- Tumors
In cats, common causes for heart murmurs include:
- Hyperthyroidism (an excess of thyroid hormone)
- High blood pressure
- Hypertrophic cardiomyopathy (thickening of the heart muscle walls)
- Heart valve deficiencies or blockages
- Defects in the heart walls
- Blood clots within the heart
- Heartworm disease (rare)
- Anemia
- Severe dehydration
What are the signs of a heart condition in your dog?
Not all dogs with a heart condition show outward signs. However, if you have been told that your dog has a heart murmur, you should watch for signs such as:
Coughing
Difficult or rapid breathing
Congestion or “noisy” breathing
Exercise intolerance
Weakness or lethargy (tiredness)
Fainting episodes
Gray or blue gums
Abdominal distention (pot-belly)
Collapse
These signs could indicate heart failure and if your dog shows any of these signs, a consult with your veterinarian is required immediately
What are the signs of a heart condition in your cat?
Not all cats with a heart condition show outward signs. However, if you have been told that your cat has a heart murmur, you should watch for signs such as:
- Difficult or rapid breathing
- Congestion or “noisy” breathing
- Loss of appetite
- Unexplained weight loss
- Weakness or lethargy (tiredness)
- Collapse
If your cat shows signs of open-mouth breathing or panting, grey or blue gums or tongue, or leg paralysis, seek veterinary help immediately!
What diagnostics test would my veterinarian make?
To determine the cause of a heart murmur, your veterinarian may recommend a number of tests, such as:
Blood tests, including heartworm tests
Chest radiographs (x-rays) to assess the heart, blood vessels, and lungs
An electrocardiogram (ECG)
An echocardiogram (an ultrasound exam to evaluate heart structure and function)
Blood pressure tests
How are heart murmurs treated?
Treatment depends on the cause of the heart murmur and your pet’s condition. Some dogs do not require any treatment initially and in this case your veterinarian will closely monitor the heart murmur and your pet’s condition. If your pet is showing clinical signs of heart disease (coughing, exercise intolerance, breathing issues, or pot belly) medication will be needed to help make your dog more comfortable and improve your pet’s longevity.
In some cases, such as when heart murmurs are caused by hyperthyroidism or dehydration, treatment of those conditions may resolve the heart murmur completely. However, if the murmur is caused by a congenital condition, your veterinarian may recommend surgery. In other cases, the heart murmur may remain, but medications can help make your cat more comfortable and improve your pet’s longevity.
Cardiomyopathy in your cat and how it's treated
Cardiomyopathy is the most common cause of heart murmur’s in cats. It is a disease affecting the heart muscle. There are several main forms of the disease – hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), arrhythmogenic right ventricular cardiomyopathy (ARVC), and dilated cardiomyopathy (DCM). HCM is the most common form encountered in cats, with the other forms being far less common. HCM is often identified in middle-aged cats and is more common in male cats than females. Cardiomyopathy can be associated with signs of heart failure and abnormal heart rhythms.
If your veterinarian is able to identify an underlying cause of the problem and this can be treated then your cat may make a full recovery. Cats with an overactive thyroid often have HCM but this will resolve if the thyroid problem is treated. In most cases, no underlying disease is discovered (or if it is there is no treatment). If the heart disease is recognized early enough long-term medication and other measures can slow the disease down but they will not stop it completely.
Long-term treatment for heart failure includes controlling exercise and administering oral diuretics to reduce fluid build-up in the lungs. In DCM the main problem is that the heart muscle is not contracting properly so drugs can be given to increase the strength of contractions. If abnormal heart rhythms are present drugs can be given to correct these.
Cats with cardiomyopathy are prone to blood clots and may need to be placed on medication to prevent this occurring. Clopidogrel is one medication that reduces the risk of blood clots forming, your veterinarian will discuss with you if your cat would benefit from this medication.
What medications can be used?
There are several different medications that may be used in dog’s with heart murmurs and cardiac disease. The most common medications are:
Pimobendan (Cardisure, Vetmedin) – the most commonly used medication. Pimobendan helps improve the function of the heart by improving the contraction of the heart muscle and dilating blood vessels to reduce the workload of the heart. Pimobendan is used in dogs with clinical signs of heart disease and has also been shown to improve longevity in dog’s with heart murmurs but without signs of heart failure.
Diuretics (e.g. Frusemide) – are used in dogs with signs of heart failure (coughing, breathing issues, pot belly) to help get rid of the excess fluid build up in the lungs or abdomen.
ACE Inhibitor (Fortekor, VetAce) – used in combination with other medications to help reduce the workload on the heart.
What ongoing treatment is needed?
6 monthly consultations with your Veterinarian are recommended to monitor your dog’s heart murmur. However, if your dog has signs of heart failure more frequent check-ups will likely be required. After the initial diagnostic tests your Veterinarian will advise when repeat testing is required depending on the degree of heart disease, in general this will involve:
Repeat cardiac ultrasound – every 6-12 months
Blood test Monitoring – every 6-12 months (especially if on medications)
Repeat Chest x-rays – every 6-12 months
Blood Pressure check – 6 monthly
If your pet is on medications they will need a consultation with the Veterinarian every 6 months to be able to continue to dispense medications. If you have any concerns or notice any changes in your pet’s condition please contact your Veterinarian immediately to make a recheck appointment.
