Anesthetics: What Are They and How Do They Help Your Pet

6 min read

By T. J. Dunn, Jr., DVM

The perfect anesthetic eliminates all awareness of pain or discomfort and is 100 percent safe. The patient is unaware of its administration and it has effects other than blocking pain perception so it allows the patient to be fully conscious and communicative. It can be given as often as needed since it is not eliminated by nor stresses internal organs.

Unfortunately, the perfect anesthetic doesn’t exist. We can be thankful, though, that a variety of highly effective and safe anesthetics have been developed and are in common use today.

The veterinarian’s goal when administering injectable and inhaled anesthetic agents is to eliminate the dog’s awareness of pain or discomfort so that needed procedures can be accurately accomplished with minimal stress to the patient. The need to have an immobile patient during a surgical procedure is obvious.

In addition, some diagnostic procedures such as radiography and CT scans or those requiring physical manipulation or restraint rely on anesthesia for proper accuracy and data gathering. Without a fully relaxed, pain-free and immobile patient many vital diagnostic and surgical procedures would never be done.

Although the perfect anesthetic described above is a fantasy, those that are currently available to veterinarians are truly revolutionary compared to what was used in "standard anesthetic protocol" just a few decades ago.

For example, intravenous anesthetics based upon phenobarbital used to be commonly employed to render an animal unconscious during surgical or diagnostic procedures. The amount needed to induce a surgical level of anesthesia would persist for over an hour before the patient would even begin to recover even if the procedure only lasted five minutes!

And for longer procedures, repeated administrations of intravenous anesthetic would result in many patients still showing effects of the anesthetic many hours and even days after the event. Cardiac suppression, low blood pressure, tissue levels of oxygen and carbon dioxide often bordered on dangerous levels, and liver function was adversely impacted. The early days of inhalant gas anesthesia using ether and other agents had potentially harmful effects on the human veterinary staff if they inadvertently inhaled escaped gasses in the surgery room air.

With modern injectable and gas anesthetic agents and with advanced anesthetic delivery machines and methods, veterinary anesthesia closely parallels the safety level that is expected and achieved in human medicine.

Modern Anethesia Safety Issues

Veterinarian Will Novak has advanced training and certification in veterinary anesthesiology and is a board certified specialist with the American Board of Veterinary Practitioners. He shared with us his insight into modern anesthesia safety issues.

"The most significant change in the last ten years is doctors providing pre-operative blood tests so that they can determine the pet’s health status prior to general anesthesia," he explained. "The second biggest change is the monitoring of the patient with such instruments as a pulse oximeter which checks the patient’s heart rate and blood oxygen levels. The use of ECG's to check heart parameters also adds a level of monitoring security."

The successful outcome of any anesthetic-requiring procedure is only in part tied to the actual anesthetic. Careful patient evaluation, as Novak states, prior to the procedure is imperative! A conscientious physical examination, thorough medical record review, blood and urine testing, and clear communication and agreement between the doctor and client regarding the pros and cons of performing the procedure are absolutely necessary for consistent success. The doctor must “know the patient”; the dog owner must know the risk-versus-benefit parameters of the procedure. The doctor-client-patient relationship should be based upon objective testing before the procedure is done; only then can realistic subjective assessment of the expected benefits be performed.

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