Veterinary anesthesia is the same as human anesthesia, and is designed to minimize pain and shock to animal patients. A veterinarian will recommend anesthesia for surgeries and medical procedures which the animal is unlikely to tolerate without sedation, and will undertake many of the same safety measures used for anesthesia in humans. Just like with human anesthesia, there are several different types of veterinary anesthesia including general, local, and conscious sedation, and the veterinarian will decide on the right one for your pet.
The first step in veterinary anesthesia is drawing blood to look for underlying medical conditions which may pose a problem while the animal is under anesthesia. While some veterinary offices offer this as an option, rather than a requirement, all pet owners should ask for blood testing to ensure that their animals are healthy. Some serious conditions do not manifest directly, and would not be noticed unless the animal was tested. While the animal's blood is drawn, it will also be weighed, so that the veterinarian knows how much anesthetic to use.
When you take an animal in for a procedure which requires anesthesia, you are asked not to offer the pet food or water for a set period of time before the procedure. While under the anesthetic, the muscles of the throat relax, and the animal may regurgitate substances which it has consumed. If aspirated into the lungs, this could be fatal. When you drop the animal off, the staff will ask when the pet has last eaten, and will take note of this on the pet's chart.
Induction of anesthesia in animals starts with an injection of a mild tranquilizer or pre-anesthetic. The tranquilizer does not cause the animal to become unconscious, but relaxes it so that it can be handled by veterinary staff. The staff starts by shaving one of the animal's legs to insert an intravenous catheter. The catheter will be used to provide drugs to the animal during the anesthetized procedure, and can also provide instant access to the vein in case of emergency. The animal's eyes are also lubricated so that they do not dry out during the surgery, and then a veterinary technician inserts an endotracheal tube into the throat of the pet. The tube is used to deliver a mixture of oxygen and anesthesia drugs. Leads are also attached to the animal's chest so that the heart, lungs, blood pressure, and general health can be monitored during the procedure.
The next stage in the process varies depending on the type of anesthetic being used. In most cases, a quick acting anesthetic is injected through the catheter to induce anesthesia, which is maintained with a mixture of anesthetic gases breathed through the endotracheal tube. In other cases, anesthesia is induced through the endotracheal tube directly. Common gases used for veterinary anesthesia include isoflurane, halothane, and desflurane. As the pet exhales, the gas is vented outside the surgical clinic to prevent human exposure.
During the procedure, a veterinary technician monitors the animal's vital signs, and alerts the surgeon to any problems which may manifest. When the procedure is finished, the anesthesia is turned off, allowing the animal to wake up naturally. A medication for pain management is also administered to minimize post-operative pain. In some cases, an injected agent to reverse the anesthetic may be used. Most animals will be slightly unsteady for several hours after anesthesia, and vomiting and other signs of discomfort may appear. For this reason, animals are commonly monitored in the veterinary clinic until they wake up fully, and are not sent home until the veterinarian approves it.