Anesthesia and Your Pet

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Golden Retriever under general
anesthesia for teeth cleaning,
blood pressure monitor and
electrocardiogram in background

Your dog is injured, the veterinarian informs you that he or she must be put under anesthesia to care for the problem. You are concerned, confused and worried. What goes on before, during and after the anesthesia procedure?

There are two main reasons an animal is placed under anesthesia: to keep them immobile and free of pain. It is not right to perform uncomfortable procedures on animals without controlling discomfort. Anesthesia (which means "without feeling") allows the doctor to do what needs to be done in the shortest period of time without discomfort or injury to the patient.

How is anesthesia delivered? As in people, there are different ways to give the anesthesia from intravenous or intramuscular sedation to general anesthesia.

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Blood pressure monitored
at 1 minute intervals during
general anesthesia

Each has it's advantages and disadvantages. Intravenous anesthesia results in a fast induction (time from administration to the time the animal is asleep) but does not last long. Some intravenous anesthetics take longer to exit the body because they require metabolism by the liver and kidney first. Sedatives are often given through the vein or muscle. In many cases sedation is sufficient to provide pain relief and motion control for short periods of time without having to use general anesthesia.

Longer procedures (greater than fifteen minutes) usually require general inhalant (gas) anesthesia. The gas is breathed in through a tube placed in the windpipe attached to an anesthetic machine which mixes the vaporized anesthetic with oxygen. The degree of anesthesia (light, medium, heavy) is controlled by the percent of gas mixture. General anesthesia is delivered through the lungs and not intravenously. After the procedure is finished your dog or cat simply breathes off the medication and recovers quickly.

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The veterinarian considers many factors such as age, procedure performed, and pre-existing conditions in order to choose the best anesthesia for the patient.

Isoflurane is one of the newest and safest type of inhalation anesthetics used in small animal practice. In most cases a preanesthetic injection is given to sedate the patient, then the gas is administered with a mask over the muzzle. Once the pet is sleeping, an endotracheal tube is placed, and the gas anesthesia is ready to be delivered. Many patients control their own level of anesthesia. When they are not deep enough they will breath harder, inhaling more anesthetic and going back to sleep. When the patient is at the correct level, the respiration will decrease and breath less gas.

Safety is the veterinarian's most important concern. Prior to anesthetic delivery the animal is examined, with particular attention given to heart and lung sounds. Diagnostic (preoperative stool, urine and blood, as well as EKG and X-rays in some patients) testing of organ function is often performed to confirm the patient can safely be anesthetized. The veterinarian should be made aware of any pre-existing medical conditions or medications your animal is taking.

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Pulse oximeter used
to monitor depth of

The patient under anesthesia is constantly monitored. Observing the color of the gums and the number of respirations per minute are helpful. Veterinarians now use electrocardiograms, respiratory monitors with alarms, and pulse oximeters (which measures the amount of oxygen inside the patient as well as the heart rate), end tital CO2, and constant blood pressure monitors. These instruments add another level of safety to the procedure.


End Tidal CO2

Anesthesia is an important part of modern veterinary practice and should not be taken lightly. If your pet needs anesthesia, many times there is no alternative. Feel free to discuss your concerns with your veterinarian and make sure he or she is using the most modern equipment and monitoring devices. Your best friend will thank you.


This page last updated on October 31, 2000
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Jan Bellows, DVM
All Pets Dental Clinic
17100 Royal Palm Blvd.
Weston, FL 33326
(954) 349-5800