Diagnostic tests such as ECGs help us to monitor the function of the heart and diagnose any potential concerns or conditions. Here, our Fairhaven vets share some information about cat and dog ECGs, when they are needed, and what to expect during your pet's appointment.
What are dog and cat ECGs?
An ECG, or as it is sometimes called an EKG, stands for electrocardiogram. This diagnostic test is used to monitor the function of the heart. Little sensors are attached to the skin and they monitor electrical activity to give a representation of what the heart is doing. This gives us the ability to gather this information without the use of invasive procedures.
What does an ECG show us about our pet's heart health?
When your pet has an ECG it provides us with valuable insight into how well the heart is working. It gives the rate and the rhythm of the heartbeat along with an understanding of the electrical impulses that are going through each section of the heart.
A normal dog or cat ECG will consist of a pattern where it will be a small bump that rises that is called the P wave, then A large spike upward called the QRS complex, and then another small bump called the T wave.
The P wave represents the atria contracting. The QRS complex is where the ventricles depolarize (The large contraction of the heart that is the typical heartbeat). And The T wave in the ventricles is repolarizing.
Your vet will look at the overall shape of each wave and the distance or timing between them. Often the concerns are the information provided by the PR interval and the QRS complex interval. These tell how fast the heart is taking in blood and how fast it is pumping it.
The next major information is to look at the peaks of the QRS complex (the big spike) and measure the distance between them. If they are a constant distance between the spikes you have a regular heartbeat if they vary in the distance you have an irregular heartbeat.
Last but not least you can read how many QRS complexes there are and calculate how many there are over a time interval and you will have the heart rate.
Is it safe for my pet to receive an ECG?
Yes, dog (canine) and cat (feline) ECGs are an incredibly safe diagnostic method. ECG is a non-invasive diagnostic test that allows for passive measurement of the heart organ.
When are ECGs needed?
There are many different situations where an ECG can provide useful information. Some of the most common are:
Abnormal Cardiovascular Physical Exam
Cardiac murmurs, gallop sounds, and arrhythmias are some obvious physical exam abnormalities that are clear indications for an echocardiogram. This can often be an indication of diastolic dysfunction and an echocardiogram is always warranted when this occurs in dogs and cats. Arrhythmias can be caused by intracardiac or extracardiac disease. An echocardiogram helps rule out primary cardiomyopathy and/or infiltrative cardiac disease that may explain the arrhythmia. Your vet may also use the information gathered to determine the best course of action for the issue at hand.
Breed Screening
Unfortunately, certain breeds are more likely to develop heart conditions compared to others. In some cases, auscultation by a board-certified cardiologist is indicated to rule out the presence of a murmur. If a murmur is auscultated, then an echo is indicated for a complete evaluation. In some breeds, however, an echo is always indicated to screen for heart disease.
Thoracic Radiographic Changes
Cardiomegaly noted on radiographs can be due to cardiac enlargement, pericardial fat accumulation, and/or patient variability. An echocardiogram is the most specific tool for determining the size of each cardiac chamber and is a very useful tool in delineating a cause for radiographic cardiomegaly. The echocardiogram is highly specific and sensitive for congestive heart failure and pulmonary hypertension.
Feline Echocardiography
Cats can be particularly challenging cardiology patients because they can have severe cardiomyopathy despite the absence of physical exam abnormalities, radiographic changes, and/or clinical signs. An echocardiogram is often the only appropriate diagnostic test that is both specific and sensitive for heart disease in cats. Purebred cats are more likely to develop heart disease so a vet may request semi-regular echocardiography to monitor for signs. If this test results in suspected heart disease, an echocardiogram is recommended in these patients to confirm the presence of heart disease and determine the therapeutic needs of the patient.
Evaluation Before Your Pet's ECG
If your dog or cat is scheduled to have an ECG your vet will also book an examination. This exam will gauge whether or not your pet can safely undergo anesthesia. Anesthesia is necessary to ensure that they remain still so we can get an accurate reading. Before placing a dog or cat under anesthesia, it can be helpful to obtain a complete understanding of the patient’s cardiovascular status.
This appointment will also allow time for instructions to be given and for you to ask any questions about anesthesia. This will include not allowing your pet to eat before their appointment to avoid complications.
How much is an ECG for a dog or cat?
Several factors can influence the cost of your pet's ECG appointment. These include but are not limited to the location of the clinic, the veterinarian, the type of pet, and more. Speak with your vet about an estimate for the cost of your pet's diagnostic testing.
Note: The advice provided in this post is intended for informational purposes only and New England Animal Hospital does not offer diagnostics using an ECG at the time this post was written.