Canine Pacemakers
Today is a big day here at Sheltie Nation HQ. Toby, our 8 year old Sheltie is heading to Massachusetts Veterinary Referral Hospital for surgery. Not just any surgery either. Barring any last minute treatment decisions by the doctors, he is getting a pacemaker later this afternoon! If you have a moment to spare, he could use a little prayer for a successful outcome today. (And I could use some prayer to help me stop from worrying myself silly!)
How we got to today’s events has been a long road. Toby has always had a laid back, calm demeanor. We never thought much of it and chocked it up to just his personality. A few years ago his regular vet altered us to his slower than average heart rate, but said otherwise he was healthy and he was acting normal. “He just has a slow ticker,” she said.
However, things began to change last year. Toby developed a persistent cough. Medication and an inhaler (yes, they do make a dog inhaler!) have only given him moderate relief. We finally had his lungs scoped but the results were inconclusive. At that point the specialist referred us to another specialist. This time a cardiologist.
After an EKG and an ultrasound, it was discovered that Toby has what they call “sick sinus syndrome”. In a nutshell, the 2 part message from his brain that tells the heart to pull in and push out the blood are not getting through consistently. This makes his heart have to work harder and grow larger to push out the double amount of blood from the missed signal. They suspect the cough could be from the enlargement pushing on his throat.
Most dogs get pacemakers because their heart rates are too slow. Symptoms of a slow heart rate show up as a dog not being able to exercise like it did in the past. It may just move more slowly and tire more quickly, or it may have fainting episodes. Thank goodness Toby isn’t fainting, but he is experiencing some of the other symptoms.
The cardiologist explained that the options Toby is facing are limited. We could do nothing and watch him decline until his heart fails, or we could have the pacemaker put in and he’d at least have a chance for a long, more fulfilling life. In fact, barring other health issues, a dog with a pacemaker will have a normal life span for its breed and size. Needless to say, learning about canine pacemakers has been an eye opening experience!
The majority of pacemakers are inserted in back of the neck on the side where the external jugular vein is. The surgeon creates a pocket under the muscle, into which the pacemaker is tucked, then sutured. A lead runs from the device down to the heart’s right ventricle where electrical impulses then stimulate it to contract, or beat, somewhere between 80 and 150 times per minute. Most of the time, once healed, the pacemaker cannot be felt by someone petting the dog.
Apparently a few thousand dogs have gotten the lifesaving implants over the past two decades. The numbers have risen from 100 to 200 implants a year in the 1990s to the current 300 to 500 a year. Some breeds are more susceptible to heart problems, and other dogs just develop issues as they age. A slow or irregular heartbeat is not caused by anything an owner does or doesn’t do. It’s something going on at the cellular level in the heart and there is a disruption in the electrical activity in some way.
A canine pacemaker has yet to be developed, so veterinary cardiologists rely on human devices that have sat too long on manufacturers’ shelves to be put into people. Many pacemakers – and the all-important leads – go through a clearinghouse, Companion Animal Pacemaker Registry and Repository, or CanPacers. It was founded in 1991 by David Sisson, D.V.M., an Oregon State University College of Veterinary Medicine professor of cardiovascular medicine. Guidant, Medtronic and St. Jude Medical make major donations of pacemakers to the clearinghouse. Prior to the formation of CanPacers, devices were donated by human patients for use in dogs after the people died. Today, nearly all pacemakers used in dogs and other animals such as cats and horses are donated by CanPacers.
Toby will be kept overnight and if all goes well he should be able to come home tomorrow afternoon. I’ll keep everyone posted on his progress. If any of you have had experiences with a canine pacemaker, we would love to hear from you too!
