The doctors at Bothell Pet Hospital will often recommend a procedure that involves anesthesia. It may be a spay, a mass removal, dental evaluation/cleaning, or major surgery. These all require that the pet undergoes general anesthesia.
While there are potential risks, current advances in technology and knowledge enable us to provide a safer anesthetic experience. In this article, I hope to allay some of these fears.
General anesthesia is a complex endeavor. All the steps are directed towards safety, pain control, and minimization of complications. So let me take you through it step-by-step.
1. Physical Exam
First of all, a physical exam is performed to detect any abnormalities that may require us to make adjustments to our standard protocols.
2. Blood Tests
Next we evaluate bloodwork: this gives us an idea of how the body organs are functioning, and how they may process the drugs we administer. For example, in a cat with chronic kidney disease, we may deliver intravenous fluids before and after the procedure. Or if there is liver compromise, we will be careful with the use of drugs metabolized by that organ.
Once we are comfortable that our patient is okay to proceed, we typically give a premedication. Most commonly we use hydromorphone, a narcotic related to morphine. Its purpose is to provide analgesia, as well as to use lesser amounts of drugs intraoperatively. Additionally, we sometimes add in a sedative. We adapt our protocols to the individual.
4. Intravenous Catheter
Next, we place an intravenous catheter. For this we need to clip a small area over a vein, usually in a front leg, so the site can be sterilely prepped. The catheter allows to administer the next stage of anesthesia, enables us to run fluids throughout the procedure, and provides a means of immediate access for emergency drugs if needed.
5. Short-Acting Anesthetic + Tracheal Tube
The pet is then given a short-acting IV drug, which “puts them under.” We are then able to intubate, or place a flexible tube down into the trachea. The tube is connected to the anesthesia machine and isoflurane, an inhalant, and oxygen are delivered directly to the patient.
6. Monitoring Equipment
All patients are connected to a sophisticated machine that enables us to monitor multiple parameters throughout the procedure.
ECG leads are attached to the body, thus providing us with continuous tracings of the heart beat and rate.
A pulse oximeter clip is applied to the tongue—this device tells us if there is appropriate oxygenation of the blood.
A blood pressure cuff is used on one of the legs and gives intermittent readings.
As the pet exhales, a capnometer measures the amount of carbon dioxide in each breath.
A warm water heating pad is placed over the patient to maintain body temperature.
One of our technicians notes all of these vital signs, charting them in the pet’s record (shown below):
So what do all of these numbers and graphs do for us?
Well, they tell us how the body is reacting to the anesthesia and the medical procedure, which allows us to make appropriate adjustments. If the heart rate is slow, we may lower the amount of isoflurane or administer atropine to bring it back to normal. If the blood pressure is low, we can increase the amount of intravenous fluids. If the carbon dioxide is too high, we may use the anesthesia machine to give additional breaths to the patient.
Once the procedure is completed, the isoflurane is turned off and the pet is allowed to breathe pure oxygen for a while, then the tube is disconnected.
Gradually, the pet regains consciousness. After it is able to swallow, the endotracheal tube is removed. The recovery is closely monitored. We evaluate for pain, administering analgesics as indicted. We ensure that the body temperature quickly returns to normal. If the pet is acting overly anxious, we may give a drug to counteract that.
Older Dogs and Cats with Anesthesia
We often hear that advanced age of a pet causes additional worry for the owner. There is no such thing as being “too old,” we just need to find the appropriate combination of anesthetic agents. And of course, there are times when the risks of anesthesia do outweigh the benefits.
The bottom line is… if you are concerned about your pet undergoing anesthesia, just ask. We will be very honest with you and discuss any risks.
by Lesley Kovar, DVM