The two types of tachycardia that do present problems and that are caused by pathological factors are atrial tachycardia and ventricular tachycardia.
Atrial tachycardia is almost always caused by either cardiac disease or conditions that have affected the dog’s body to such an extent that the heart stops functioning normally along with the rest of the other organs.
Ventricular tachycardia can have one or several different causes, such as the following:
- Pulmonary conditions
- Birth defects
- Gastrointestinal conditions
- Medication overdose
- Low blood pressure
- Abnormal serum levels of potassium or calcium
- Splenic disease
A rapid heart rate, complete with all of the complications that it can cause, is a risk that tends to affect certain dog categories more than others – pregnant dogs, those that have primary heart disease, or those undergoing treatment for thyroid conditions have a much higher likelihood of experiencing the worst symptoms of tachycardia.
When ventricular tachycardia happens, time is of the essence. The ventricles are in charge of pumping the blood from the heart to all of the other organs, so when they start malfunctioning, the dog could lose their life in a short amount of time.
Some dogs are more likely to have ventricular tachycardia simply because they are born this way – Boxers are a good example of a breed that’s more predisposed to it.
What symptoms does tachycardia cause?
Regardless of the exact type that a dog might be experiencing (particularly if they have ventricular tachycardia), the clinical signs that can be noticed are typical for an acute malfunction of the heart.
Consequently, pets can experience the following:
- Intolerance to any form of exercise, including climbing the stairs or jumping on the couch
- Shortness of breath
- Pale mucous membranes
- A weak pulse
- Sudden collapse
Some dogs can simply die after beginning to experience the symptoms of ventricular tachycardia without their pet owners even having the time to take them to the veterinary clinic. If you know that your dog has a heart condition and you start noticing some of the previously mentioned symptoms, take them to the animal hospital right away.
How is a rapid heart rate diagnosed?
While there are a variety of tests that can be performed when you get to the vet, in both atrial and ventricular tachycardia, the only diagnostic method that can lead to an accurate and clear diagnosis is an electrocardiogram (an ECG).
If the heart rate is not ventricular and seems to have an unapparent cause, the vet will perform a number of effort tests, along with a chemical blood profile, urinalysis, a complete blood count, and a wide range of other tests that could lead to a different diagnosis.
Since a rapid heart rate can also be caused by pulmonary conditions, it is of utmost importance for the vet to rule out any lung disease, including cancer.
In some situations, a Halter monitor might be able to provide valuable information as to how the dog’s heart functions over a period of 24 hours – especially in cases where the tachycardia is not life-threatening. Any medication that is administered for the symptom itself can lead to changes in the way the heart functions, so using a Halter monitor could be worthless as the results might be inaccurate, especially after treatment is initiated.
How is tachycardia treated?
Until a diagnosis is confirmed, tachycardia can only be seen as a symptom instead of a disease, which means that the dog can only receive symptomatic therapy so that their condition is stabilized and they don’t risk losing their life.
After the cause of the clinical picture is discovered, the vet could administer a number of medications that solve both the primary issue that has led to the rapid heart rate and the clinical sign itself.
Antiarrhythmic therapy does exist, and in veterinary medicine, the two most common medications that are used for this purpose are sotalol and lidocaine. Procainamide is also utilized to treat ventricular tachycardia, along with two other conditions, atrial fibrillation, and ventricular premature complexes.
Atenolol and amiodarone are also commonly utilized for treating tachycardia, with the second one being more popular in Europe than in North America at this time. A combination of mexiletine and atenolol or sotalol seems to be quite effective in reducing the intensity of the symptoms of ventricular tachycardia.
In supraventricular tachycardia that causes the dog to experience a heart rate higher than 240 beats per minute, drugs such as dobutamine or diltiazem can prove to be more or less effective.
Recovery and prevention of rapid heart rate in dogs
Continuous monitoring can be quite helpful when it comes to dogs that have been treated for tachycardia. There are also a number of lifestyle changes that pet owners have to ensure to prevent the symptom (or condition) from recurring, such as limiting the amount of strenuous exercise that the dog gets, helping them lose weight and more.
Keeping your dog’s arrhythmia in check at home can be done with the prescription medication that your vet has recommended. In general, dogs with heart conditions or whose cardiac muscle has been affected (whether more or less) need to be kept under strict observation. Consequently, you may need to take your pet to the vet once a month after treatment and once every 2-3 months until their condition improves.
Some heart complications may never be prevented, especially if they are caused by birth defects or even electrolyte imbalances. The majority of pet diets these days are somewhat balanced in this respect, but every dog’s body is different, so they can develop cardiac symptoms for a wide range of reasons.