Staying in Pace with Pacemakers

What would you do if your pet's heart suddenly stopped working properly? February is the month of National Heart Awareness and Valentine's Day. February should also be a reminder for pet owners to educate themselves on their pet's heart health. The best place to start is your veterinarian.

If your pet has an irregular heartbeat or low heart rate it should be evaluated by your veterinarian and may indicate the need for a pacemaker.

"Pet owners are often amazed that their pets can live for years and feel much better than they have in a long time after receiving a pacemaker," says Dr. Ashley Saunders, assistant professor at the Texas A&M College of Veterinary Medicine & Biomedical Sciences (CVM).  "Even younger working dogs that assist in border patrol and drug sniffing are able to perform their duties the same way a normal dog would after receiving a pacemaker."

Dogs with low heart rates tend to move slower and are likely to tire more quickly, because blood is not being efficiently pumped to the rest of the body. They may experience symptoms such as fatigue, fainting, weakness, coughing, and a swollen abdomen. 

"Canine heart rates usually range from 80 to 150 beats per minute, but when rates drop below 80, pacemakers may be suggested to provide the users with 'artificial cardiac pacing' thereby raising and stabilizing their heart rates," Saunders explains.

Veterinary cardiologists performing pacemaker surgery generally set the pace of the heart at a rate specific to each patient allowing continuous stimulation for every heartbeat.  The two-hour surgical procedure is often done in one of two ways: transvenous (through the neck) or epicardial (through the abdomen). 

"The most common method used in veterinary medicine is transvenous," Saunders said.  "This procedure allows us to create about a three-inch incision in the neck exposing the vessel and allowing the pulse generator or battery enough room to comfortably reside." 

Before the pulse generator is introduced, a pacing lead is inserted into the vessel and passed through the tricuspid valve and into the right ventricle where it successfully transmits an electrical charge from the pulse generator to the heart.    

Saunders says surgical patients are usually kept overnight for observation and brought in for a one-month check-up following the procedure and then evaluated every six months. Pet owners are advised to keep their animals calm for two to four weeks after surgery so they can properly heal. 

Pet owners are also advised to use a harness instead of a collar if the pulse generator is placed inside the neck. 

"A lead can be pulled out of place if the animal is too rambunctious during the two-to-four-week healing period," Saunders said. "If this happens the heart rate may return to its originally slow rate. Once you pace a dog's heart, it often becomes dependent on the pacemaker."

This dependency is less of a problem for pets after recovery because the body forms a type of cast around the pacemaker keeping it in place. After recovery, pacemakers have a long life and function like a wristwatch battery. 

"If the pacemaker begins to show signs of wear, it will not stop automatically," Saunders adds.  "It will first slow down, dropping the heart rate. That's why the check-ups are so important. Canine matters of the heart are best solved by those who love it most - its owners and its veterinarian," Saunders believes.

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Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. Stories can be viewed on the Web at /pet-talk.

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*Above Photo: Dr. Saunders is checking a pacemaker, Middle Photo: pacemaker next to a quarter, Bottom Photo: X-ray photo of a pacemaker.