Heart Murmurs

In the month that celebrates love (Valentine’s Day), I thought we would talk about HEARTS! Just like with humans, there are several diseases and illnesses that can affect the heart. This week’s blog will discuss heart murmurs. A heart murmur is an abnormal swishing noise in the heart. During exams, your vet will use a stethoscope to listen to your pet’s heart and lungs. During this part of the evaluation, if the vet hears anything unusual, they will assess which area of the heart is affected the timing of which the murmur is heard and give it a grade on a scale of 1-6. Unless you are a cardiologist or have had several experiences with heart murmurs, the diagnosis can be very concerning. By knowing some of the terminology that is used, it can help ease some of the concern.


The first group of words describes the location in which the murmur is heard the loudest. Dogs and cats have a very similar vascular system to humans. There are four chambers of their heart (left and right atrium and ventricle). It can refer to either the valve of the heart or the location in relation to chest structures. They are:


  • Aortic – left side of the heart.
  • Mitral – left side of the heart.
  • Tricuspid – between the right atrium and the right ventricle.
  • Pulmonic – the upper right side.


The cardiac cycle is the “lub-dub” sound the heart makes. Changes in this “lub-dub” pattern are considered a murmur. Depending on when the murmur is heard will give it another term. These terms and what they mean are:


  • Systole – the phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries.
  • Diastole – the phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood.
  • Continuous – the murmur happens during both the systolic and diastolic phase.


Heart murmurs use a grading scale from one to six – with six being the worst. While your dog or cat may seem fine on the outside, they can still have some complications on the inside. That is why it is of the utmost importance to have your pet receive their yearly wellness exam. All too often, vet hospitals hear “my animal isn’t that old” or “they seemed fine just a little bit ago…” and those lines of thought can be deadly for your pet. If a heart murmur is caught early and treated, murmurs can be managed long term.  Two of my cats were diagnosed with a grade 1 heart murmur when they were just a year old. Obviously, they were not that old and they did not show any signs of illness, and we were able to catch it during their yearly health exam. They are currently 5 1/2 and 3 years old.  The grading scale consists of:


  • Grade 1 – Murmur can only be heard in a quiet room after several minutes of listening.
  • Grade 2 – Murmur can be heard immediately but is very soft.
  • Grade 3 – Murmur has a low to moderate intensity.
  • Grade 4 – Murmur is loud by doesn’t have a palpable thrill.
  • Grade 5- Murmur is loud with a palpable thrill.
  • Grade 6- Murmur is loud and can possibly be felt through the chest.


Depending on the grade of heart murmur, the veterinarian could suggest blood work and / or X-rays to further evaluate the condition of your pet’s health. The X-rays can help the veterinarian determine the size of your pet’s heart. Veterinarians use what is called the Vertebral Heart Scale to assess the size of the heart. By using the Vertebral Heart Scale, vets can monitor the heart size throughout the rest of it’s life.


There are a few medications and supplements available to help maintain your pet’s heart health. They should only be used under a veterinarian’s directions – NEVER give your pet any of your own heart medications!!


In certain cases, your pet’s heart condition may be required to go to a specialist.


Show your pet some love by having their heart checked out today!


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