By Dr. Karen Shaw Becker
There are many medical procedures that have crossed over from human to veterinary medicine, and one of them involves a lifesaving device I'm sure you've heard of — the pacemaker.
Cardiologists have been implanting pacemakers in humans for over 50 years. The first dog to receive one was a 10-year-old Basenji with recurrent congestive heart failure.1 The pacemaker was implanted in 1967, after having been removed from a human patient who passed away six months after receiving the device.
The Basenji underwent an electrocardiogram (EKG) every six months and the pacemaker functioned normally for five years and four months, at which time the dog developed an irregular heart rhythm and began fainting. Since he was still in good condition at 15 1/2 years, the pacemaker was replaced. The dog lived another six months, and was euthanized when an (unrelated) abdominal mass was discovered.
Pacemakers are placed to save the lives of dogs with life-threatening arrhythmias (abnormal heart rhythms), as well as dogs whose heart rate is too slow to allow them to exercise and live an otherwise normal life.
How Pacemakers Work in Dogs
There are actually two parts to a pacemaker. One is the device itself, which is a tiny generator with a lithium battery and a computer chip that is programmed to meet each dog's individual needs. The other part is the leads or wires that run from the generator through the veins in the neck to the inside of the heart, where they are attached.
When the dog's heart rate slows to a point below the programmed range, which is generally between 80 and 120 beats per minute, the pacemaker is activated and stimulates contractions of the heart until the rhythm is reset and remains consistent.
Dogs receiving a pacemaker are placed under anesthesia for the implantation. The veterinary cardiologist makes a small incision in the neck and feeds the leads through the external jugular vein, and the generator is placed in the skin. The vet then uses fluoroscopy to look at the leads going into the heart to insure they're attached correctly.
The procedure is minimally invasive, and while the devices are the same ones used for humans, the surgery itself is much less costly — typically between $3,500 and $4,000, according to veterinary cardiologist Dr. Ryan Fries at the University of Illinois Veterinary Teaching Hospital in Urbana.2
However, according to Embrace Pet Insurance, the cost of diagnosis and pacemaker placement can range from $5,000 to $15,000,3 so if your dog needs a pacemaker, make sure you have a good understanding of the costs involved. Dogs are typically required to rest for about a month after pacemaker placement, and it's extremely important to immediately switch from a collar to a harness to insure there's no pressure on the neck.
If your dog has a pacemaker, she'll need to be seen every six months, ideally with alternating visits between her regular vet and her veterinary cardiologist. Adjusting the settings on the pacemaker is simple and noninvasive, and involves simply placing a magnet on the skin over the device.
"Pacemakers may offer the only treatment option that allows a dog to return to a normal life," says Fries. "We even put them in working animals that return to their jobs. They are more common than you would think. There are no outward signs to tell the difference between a dog with or without one!"
3 Canine Heart Conditions That Can Be Treated With a Pacemaker
1. Sick Sinus Syndrome (SSS)
There are certain breeds with a genetic predisposition to heart abnormalities such as sick sinus syndrome, a condition in which the sinus node in the heart doesn't work as it should, resulting in long pauses between heartbeats. In dogs with SSS, the sinus node doesn't consistently discharge an electrical impulse to trigger the heart to contract.
The result is a long pause between heartbeats, or put another way, the heart literally stops beating. If the heart stops for over eight seconds, the dog will pass out. Sometimes an electrical impulse from another part of the heart will trigger a beat to prevent complete arrest.
These rescue beats tend to be very rapid. In most cases, the sinus node will at some point begin doing its job again, providing periods of a normal heart rate of 60 to 100 beats per minute, interspersed with pauses.
Some dogs with SSS have a consistent, abnormally slow heartbeat (sinus bradycardia) as the result of a low firing rate from the sinus node. Even during exercise or when excited, the dog's heart rate will be under 40 beats per minute. Other dogs with the condition will have episodes of rapid heartbeat (excessive tachycardia), plus long pauses.
The condition is primarily seen in middle-aged or older female Dachshunds, Cocker Spaniels, West Highland White Terriers, Pugs and especially, Miniature Schnauzers.
2. Atrial Standstill
English Springer Spaniels are predisposed to another type of heart problem called atrial standstill, a rare heart rhythm disturbance that is typically confirmed by an EKG. The test identifies missing P-waves, which are a measure of electrical activity in the atria or top two chambers of the heart, and may also show a slow heart rate with either regular or irregular rhythm.4 Atrial standstill can be temporary, persistent or terminal due to complications such as heart failure.
3. Advanced Atrioventricular (AV) Block
Advanced AV block is a condition in which the electrical impulse that triggers contractions of the atrium does not transfer appropriately to the ventricle.
The heart contains a sinoatrial node (SA), which controls the heart rate. This electrical system generates impulses or waves that are transmitted through the AV node to the ventricles, which stimulates the muscles of the heart to contract and push blood through the interior arteries and throughout the body.
An advanced AV block (also called a complete or third-degree block) means the electrical impulses transmitted by the SA node are blocked at the AV node, which causes heart rate abnormalities. Cocker Spaniels, Doberman Pinschers and Pugs are predisposed to the condition, which is seen more often in older dogs.5
Additional Options for Dogs With Heart Arrhythmias
There are medications conventional veterinarians often use to try to maintain a normal heart rate in dogs. These are called vagolytic drugs such as theophylline, terbutaline and propantheline bromide. Beyond their common side effects, these drugs aren't consistently successful and carry a significant risk of worsening the extremes of a too-fast or too-slow heart rate, so I don't recommend them.
Even though arrhythmias begin as an electrical problem in the heart, many dogs end up with heart failure as a result. That's why I recommend discussing heart supportive nutraceuticals such as ubiquinol, krill oil, acetyl-l-carnitine, taurine, Hawthorne extract and D-ribose, as well as a homeopathic or TCM (Traditional Chinese Medicine) work up, with a holistic or integrative veterinarian.
These adjunctive therapies may help nourish and support overall heart health, reducing the likelihood of congestive heart failure over time. Interestingly, acupuncture (yes, there's a heart meridian!) may also benefit these patients.