By Alan Green and Samantha Nelson
Most of us are familiar with anesthesia either from personal experience or the experience of a friend or loved one. This month’s guest contributor, Dr. Samantha Nelson, is one of CVRCs board-certified surgical specialists. Dr. Nelson does an excellent job of explaining the important highlights of the anesthetic protocol and what you need to be aware of when faced with putting your pet under general anesthesia.
You’ve just been told by your veterinarian that your pet needs to have general anesthesia, or “be put under,” for a procedure. This is a scary prospect for most pet owners, but the good news is that anesthesia has advanced tremendously in the past 10-20 years and, as long as performed appropriately, is very safe. While severe complications are possible (e.g. cardiac arrest), they are very rare (a risk of death less than one in 1000).
General anesthesia uses a combination of drugs to induce a state of pain-free, motionless unconsciousness. Before inducing unconsciousness, it is important for your pet to be calm and stress-free, so a “premedication” is given. This is generally a combination of a narcotic pain medication and a sedative. Once pre-medicated, they are given an “induction agent” — a fast-acting injectable drug that induces unconsciousness and allows placement of the endotracheal (breathing) tube. Once the tube is placed, a mixture of 100 percent oxygen and the anesthetic gas is started. The anesthetic gas allows unconsciousness to be maintained as long as needed for the procedure. Once the anesthetic gas is turned off, your pet awakens within minutes. They are closely monitored during the recovery period. The breathing tube is left in place until they are breathing well and swallowing on their own.
During anesthesia, your pet’s vital signs are closely monitored. Monitoring is one of the most important components of anesthesia, allowing the anesthetist to catch an impending complication and make adjustments before a problem starts. Parameters to be monitored include heart and respiratory rate, EKG, blood pressure, blood oxygen and carbon dioxide levels and temperature. Additionally, an IV is placed to administer IV fluids to support circulation and for rapid administration of drugs (e.g. pain medications, but also resuscitation drugs if needed).
Risks of anesthesia vary from mild, common and treatable (e.g. low blood pressure) to — rarely — severe and life-threatening. While risk is minimal in healthy pets, there are situations where severe adverse events can occur (e.g. critically ill patients). Though age itself is not considered a disease or risk for anesthesia, older pets are more likely to have concurrent diseases that can increase anesthetic risk. Pre-existing organ dysfunction (e.g. liver, kidney, heart disease) can increase risk, even if not previously detected. Because of this, a complete history, physical exam and pre-anesthetic bloodwork are necessary. Additional testing (e.g. heart ultrasound) may be recommended prior to anesthesia if abnormalities are found.
You will be asked to fast your pet the night before anesthesia. An empty stomach significantly decreases the risk of aspiration pneumonia, which can occur when stomach contents reflux into the throat and are breathed into the lungs. The chance of this is very low with a breathing tube in place, but it can occur if small amounts leak around the tube, or during the induction or recovery period before/after the tube is in place. Severe allergic (anaphylactic) reactions to anesthetic agents are very rare, but do occur.
What can you, as a pet owner, do to minimize your pet’s anesthetic risk? A lot! First, inform your veterinarian about all prior and current illnesses, prior anesthetic events/surgery, especially if any complications occurred and all medications/supplements your pet is on or has recently taken. Keep your pet healthy and up-to-date on wellness care. Follow your veterinarian’s instructions for fasting and which medications to give or avoid. And finally, don’t hesitate to ask questions about the procedure, monitoring and what to expect after going home.
At CVRC, our specialists have all received advanced training in anesthesia, our technicians are highly skilled in monitoring and administering anesthesia and all pets undergoing anesthesia receive custom protocols, monitoring and care comparable to human hospitals.