Animals & Anesthesia – By: Dr. Kristen Kline
Animals & Anesthesia – By: Dr. Kristen KlineDate: August 1, 2014
Veterinarians are often confronted with pet owners who decline to have important surgical procedures performed on their pet due to fear of anesthesia. This article will hopefully serve to allay some of those fears and provide a detailed explanation of what an average anesthetic veterinary procedure entails.
Prior to scheduling an anesthetic procedure, your veterinarian will review your pet’s previous medical history and perform a pre-anesthetic physical examination to identify any potential anesthetic risk factors. Often pre-operative blood screens, x-rays, or electrocardiograms are recommended to ensure the pet’s essential body systems – heart, lung, liver and kidneys – are functioning properly.
Once a pet is cleared for anesthesia you will be advised to withhold food and water from your pet for several hours prior to anesthesia. This helps minimize the risk of vomiting or regurgitation during anesthesia which could result in aspiration of food material into the lungs. Pre-anesthetic mediations are usually administered to relax and calm the pet before surgery, and also provide benefit post-operatively allowing for a smoother recovery from anesthesia. Commonly used pre-anesthetic medications include diazepam (Valium) which relieves anxiety, and opioids such as butorphanol or hydromorphone that relieve pain and provide sedation as well. An intravenous (IV) catheter is then placed into a vein usually in the front or hind leg to allow easy administration of anesthetic drugs and intra-operative fluids. Administration of intravenous fluids during anesthesia helps maintain hydration and adequate blood pressure.
At this point the pet is ready for induction of anesthesia. Animals that have any respiratory ailments or abnormalities are often administered oxygen for a few minutes before anesthetic induction to help make sure they do not suffer from low oxygen at any time. Short-acting anesthetic drugs such as propofol or ketamine are administered intravenously to permit placement of an endotracheal (ET) tube into the windpipe, which then delivers oxygen and anesthetic gas to the lungs. The most commonly used anesthetic gasses in veterinary medicine are isoflurane and sevoflurane. Once the ET tube is in place the veterinarian is able to control the pet’s breathing and assist with breathing if necessary. The tube also helps protect the airway from aspiration of stomach material during anesthesia.
Veterinarians use a variety of equipment to monitor pets while they are anesthetized. Pulse oximetry gives information about the pet’s blood oxygen level and heart rate. Blood pressure measurement, electrocardiogram, and carbon dioxide exhalation are other important parameters that can be monitored as well. A skilled veterinary nurse who monitors pulse quality, heart rate, anesthetic depth, and amount of anesthetic gas delivered is the most invaluable key to safe anesthesia.
As the surgical procedure winds down, the anesthetic gas level is gradually reduced so the pet is able to wake smoothly. Small procedures such as nail trims and ear cleaning are often performed during this time before the pet is fully awake. Once the pet is able to swallow and sit up on its own the endotracheal tube is removed.
Veterinarians strive to make every anesthetic procedure as safe as possible for your pet. If you ever have questions or fears about any anesthetic procedure please take the time to ask your veterinarian so they can explain it to you and help you make an informed decision.