By John Andersen, DVM
Many of us pet owners have heard horror stories of healthy pets dying while under anesthesia for a routine procedure. Some-one brings a beloved pet in for a routine spay or dental cleaning, only to have their worse fears realized with a call from the vet delivering shocking news.
I am here to tell you that fortunately those days are for the most part GONE! That’s right, even for a 15-year-old dog, anesthesia done properly is very safe and is a minimal risk to your pet’s health.
So, what exactly are we talking about when we say “anesthesia”? General anesthesia is the process of giving injectable and or inhalant drugs to patients (human or animal) to render them unconscious and unable to feel any pain. In a typical small animal veterinary hospital, anesthesia is generally used for performing surgery and dental cleanings/extractions.
Long ago, this process was not well refined. The drugs that put people and animals asleep were sometimes too strong and led to complications such as cardiac arrest and death.
These days, anesthesia is a smooth process in trained hands. With the right combination of drugs, monitoring, and fluid and heat support, there is a minimal chance of problems occurring. In fact, in my more than 10 years of practicing veterinary medicine, I have never lost one single healthy patient unexpectedly to anesthesia. Not one. Yet I am still hyper-alert and nervous every time we put a client’s pet under anesthesia. I fully feel the pressure that we have been entrusted with this pet’s care and we do everything we can to ensure that no errors are made.
I have lost a few patients under anesthesia over the years, but these have all been fairly critical patients to begin with. All of them were urgent or emergency surgical cases such as removing a hemorrhaging spleen, bleeding cancers, or infected/septic organs. These animals were not good anesthetic candidates in the first place.
A detailed account of a typical anesthetic procedure should clear up the mystique of anesthesia a bit. As I love to talk about my own pets, we’ll take the story of our Labrador retriever, Boone, on the day he lost his manhood, I mean, was neutered.
Boone woke up that morning like any morning, incredibly eager to be fed breakfast. As is his routine, he bolted right to his food bowl, convulsing with excitement. But this morning, there would be no breakfast. It is important to have an empty stomach before undergoing anesthesia to minimize the risk of aspiration. This is when food/fluid from the stomach flows back out through a relaxed esophagus and down into the lungs. Boone knew then that it was going to be a bad day.
We made our way to the office. If he were a regular client, he would have been checked in by one of the nurses. This is your last gut check as a client, when you have to sign the anesthesia consent form that clearly states that unforeseen risks can occur, including death. Yikes! We, of course, reassure people that the risks are low and we are careful. And we realize that when we are handed that leash, we have been handed something very precious to that person and we take that responsibility personally. Some people are lighthearted and humorous about it while other people are literally in tears as they see their pet leave the room.
Boone’s next stop was the treatment area. He was starting to get really suspicious now as his dad started looking at him with weird things like stethoscopes and otoscopes. Then his temperature was taken. Yep, it was gonna be a bad day. After making sure his heart and lungs were fine and there were no other obvious concerns, we drew some blood to make sure his internal organs were ok. Most importantly, we wanted to make sure the liver and kidneys were functioning well to process the anesthesia. Boone got put in a run with a blanket and pat on the head and had to wait around for a bit.
His labwork looked great, so we got Boone out and gave him his premedication—an injection of a sedative. This has a few purposes. First, it allows us to get an IV catheter into him without him resisting and fighting us. Some dogs would much rather bite us than allow us to poke them with an IV. Second, it allows us to use less gas anesthetics, which makes the anesthesia safer. Boone felt a pinch in his rear leg and wondered what just happened. In a few minutes, he started to feel good—reeeal good. Soon he forgot what he was thinking about.
We got Boone up on a treatment table and our veterinary technicians (the nurses of the vet field, highly skilled and trained) got an IV in his leg and we started IV fluids. IV fluids are probably one of the most important parts of anesthesia. They help to keep blood pressure from dropping, which can cause significant problems. Next, one of our technicians gave him the “induction” agent, an IV injection of another type of sedative that rendered him completely unconscious (but still breathing) for several minutes. The nurses then skillfully inserted an endotracheal tube. This is a breathing tube that goes down into the windpipe (trachea) and to which we attach the anesthesia machine.
With Boone fully out and “tubed up,” he was moved into the operating room. There was a flurry of activity as his breathing tube was hooked up to the anesthetic machine and all of the monitoring equipment was attached to him. The anesthesia machine delivers a mixture of pure oxygen and isofluorane, the gas anesthetic. This gas is what kept him under anesthesia for as long as the procedure took. There was a rubber bag on the machine that we used to give him breaths regularly as needed.
Although Boone was unconscious, we were very aware of his body. He was hooked up to an electrocardiogram (EKG), which showed us real-time electrical impulses of his heart rate and rhythm. He had a pulseoximeter on his tongue that measured the oxygen saturation of his tissues. We also measured the amount of carbon dioxide in his exhaled air to make sure he was ventilating enough, keeping CO2 from building up in his bloodstream. And he had a temperature probe down his esophagus to let us know if his temperature dropped. And last but not least, he had a veterinary technician with a brain, eyes, ears, and a stethoscope to process all of that information and make any adjustments necessary to ensure that his anesthesia was safe and boring. Oh, and of course me, doing surgery with part of my brain and helping to watch anesthesia with the remainder.
Boone’s neuter was quick and easy. He was given some injectable pain meds to help when he woke up, as well as some local anesthetic at the surgical site to numb things up for a while. Then it was time to wake up. We simply turned off the isofluorane gas and kept him breathing pure oxygen for a while. It took about 10 to 15 minutes for him to start to stir and attempt to swallow. We unhooked all of the monitoring equipment and when he seemed able to swallow, we pulled the breathing tube out.
Most dogs have a little freak-out moment at this point. They can’t really comprehend what in the world is going on as they regain consciousness in a cage with people wearing masks looking at them! Hoowwwllll!! There was a brief struggle as we calmed Boone down and finally he sighed and laid his head down and started to snore. He was awake, but very groggy. He stayed until it was time to go home, gradually waking up some more as the day moved on.
At the end of the day we took his IV out and hooked up his leash. His first steps out of the cage were wobbly and goofy, but he quickly caught on and in no time was dragging me down the hallway, reminding me that he still hadn’t had his breakfast.