What are the largest risk factors for anesthesia? You are about to put your favorite 14 year old cat, Rotten Tooth, under anesthesia for a dental procedure. You are concerned about the risks of anesthesia and you ask your veterinarian for assurance that Rotten Tooth will come home and not die while undergoing the extractions and cleaning.
She tells you:
Weight is a major factor in anesthetic risk. The increased weight changes the metabolism of some medications, and makes the heart and organs work harder to accomplish the same thing. Many veterinarians do not take into account the lean body mass in calculating dosages and can over-anesthetize your overweight pet inadvertently, making recovery long and difficult. But in my opinion, weight is not the ‘largest’ factor.
Organ function is crucial in metabolizing the medications. Most meds are excreted via the liver or kidneys, and impaired function can cause your pet’s body to retain the medications and thus not wake up. Pre- anesthetic blood work in absolutely necessary to be aware of these issues and for the veterinarian to design an anesthesia protocol specific for your pet, or even evaluate the risk ratio of continuing with the proposed dental (or other surgery). From a medical standpoint, this information is some of most important values in evaluating risk to your pet, and I would hope that all modern veterinarians understand and are requiring blood work prior to anesthesia. I implore you to never ‘opt out’ of doing this blood work, even for spay and neuters, as it is always crucial for safe anesthesia.
Yet there is still another factor that is as important as body condition and organ function. Stress is an enormous, largely ignored, risk factor to anesthesia.
So, is your pet stressed when getting anesthetized? OF COURSE!! Especially if you have chased your cat in the wee hours of the morning, stuffed him into a carrier, hauled him in your car while he yowled and got tossed around despite your careful driving in morning rush hour traffic, then arrived in a busy veterinary hospital with five other traumatized pets all getting admitted for the day. Next he gets pulled out of his carrier, weighed and stuffed into a hospital crate that smells of disinfectant and looks like- well, a hospital. He is pulled out again and had his blood drawn (hopefully), a catheter placed (HOPEFULLY!), and then given pre-anesthetic injections. The actual procedure is not too scary because he is asleep, but as he awakes to bright lights and unfamiliar sounds, he desperately looks for a comforting face and a soothing voice- you- but you are nowhere to be found.
Do you think he is stressed? Poor Rotten Tooth is having a rotten day. So why is stress bad for him? Obviously we want him happy, but is stress really all that important to anesthesia?
It increases the cardiac rate, placing more requirements on the body and a higher demand of the heart, which can lead to cardiac arrest.
It changes the anesthetic requirements, making medication dosages variable, potentially causing the medications to be overdosed, causing coma or death.
It causes respiratory changes, which hinders oxygenation to the brain, which is essential to life.
It causes a variety of increases in catecholamines, endorphins and neurotransmitters that will change the pet’s response to meds, its brain waves, heart rate and metabolic rate- all of which are necessary for appropriate handling of anesthesia.
It can cause nausea and vomiting, creating an increased risk of aspiration pneumonia.
Does that mean Rotten Tooth’s owner should by-pass the entire thing and let him suffer with a horribly abscessed tooth? Absolutely not. The tooth causes horrific pain, stress and ultimately sepsis and heart disease.
Second option: Reduce stress.
Now that your stressed out by reading all this, lets focus on HOW to reduce stress… can anyone offer ideas? Let’s run a week discussion group on methods to reduce stress in your pet prior to, during and after an anesthetic procedure. I have my ideas, but I’d love to hear yours!