Pets and anesthesia

Many veterinary procedures require your pet to be put under anesthesia so that it will not feel pain and will remain still. Like any medical procedure, anesthesia does have risks, but most healthy animals, including older pets, don’t have any issues and recover rather quickly.

How do I know if anesthesia is safe for my pet?

A thorough history of current and past medical problems can provide valuable information about your pet’s physical condition when planning an anesthetic procedure. Your veterinarian will also perform a physical examination and may recommend additional testing to ensure anesthesia is safe for your pet.

You should communicate any concerns about your pet’s health to your veterinarian prior to scheduling surgery. Any signs of exercise intolerance, weight loss, a recent change in urination or defecation, and mental alertness are particularly informative and may require further diagnostic workup.

A physical examination may reveal abnormalities of the heart or lungs that could require further evaluation with an electrocardiogram (ECG), chest X-ray, or heart ultrasound prior to performing general anesthesia.

Many anesthetic drugs affect blood flow to major organs and are inactivated by the liver, so your veterinarian may evaluate a blood sample for anemia and for kidney and liver function prior to deciding which anesthetic technique to use.

Can I give my pet food or water before anesthesia?

You should withhold all food from pets scheduled for elective surgery for at least 12 hours prior to arriving at your veterinarian’s clinic. The presence of food in a pet’s stomach will increase the likelihood of aspiration of food into the lungs should your pet vomit during induction of general anesthesia. Water is not usually withheld but check with your veterinarian.

How is my pet monitored while under anesthesia?

Close monitoring of vital signs such as blood pressure and heart and respiratory rates during anesthesia allows for early recognition and correction of problems.

An animal’s depth of anesthesia is determined by evaluating reflexes, muscle tone, and response of vital signs to surgical stimulation. If an animal is judged to be too light for the surgical procedure being performed, an increased amount of anesthetic is administered. Conversely, if the patient is judged to be in an excessively deep plane of anesthesia, the amount of anesthetic administered is decreased.

Is anesthesia dangerous for pets?

Some think of general anesthesia as a relaxing sleep, but it is probably more accurate to compare it to a period of very strenuous exercise. Just as young, healthy animals are more able to exercise vigorously, they can better tolerate the depression in heart function caused by general anesthesia because they have such great cardiovascular reserve. Older or debilitated animals have less cardiovascular reserve and may have less tolerance for general anesthesia. Older or debilitated animals often recover from general anesthesia and surgery more slowly than young patients.

How long will it take for my pet to recover from anesthesia?

After general anesthesia, animals are likely to be affected by the anesthetic drugs for several days. An animal may exhibit behavioral changes for a few days and act as if it does not recognize familiar surroundings, people, or other animals. Behavioral changes after general anesthesia are extremely common and usually resolve within a few days.

Do not leave young children unattended with an animal that has just recovered from general anesthesia no matter how trustworthy the animal normally is. There are reports of normally well-behaved dogs returning home after surgery and anesthesia and biting young children for no apparent reason.

A pet’s ability to control its body temperature may be affected during the recovery period. For the first few days after general anesthesia, it is recommended to keep your pet in a warm, though not overly hot room. Cold weather breeds such as malamutes and huskies tend to retain heat easily and a cooler environment may be more appropriate for these breeds.

Obese animals often have delayed recoveries. Most general anesthetics are very fat-soluble, so the greater the amount of body fat and the longer the animal is anesthetized, the greater amount of anesthetic agent that will be absorbed into body fat. Anesthetic taken up by body fat will leach back into an animal’s blood for days or even weeks after anesthesia. This low residual amount of anesthetic may continue to affect an animal’s behavior for several days.

This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your pet incurred by following these descriptions or procedures.