Saturday, February 11, 2012

What Do You Need To Know About Anesthesia?

Reviewed by John A. Bukowski, DVM, MPH, Ph.D. and Susan E. Aiello, DVM, ELS

When your dog needs to be anesthetized for a medical procedure, it’s normal to be nervous. In addition to concerns about the procedure itself, pet owners usually have many questions about anesthesia: What kind of anesthesia will be used? What are the side effects? How is it administered? Will my pet feel any pain at all? Can the procedure be done with a local anesthetic or does my pet have to be ‘put under’? How will my pet be monitored during the procedure? What are the risks?

The basics: anesthesia/analgesia/sedation
  • Anesthesia means the loss of sensation or awareness of pain.
  • General anesthesia is anesthesia accompanied by loss of consciousness.
  • Local anesthesia is a loss of sensation or awareness of pain in a particular part or region of the body. When local anesthesia is administered, the animal remains conscious, though it may be given sedation.
  • Analgesia is the loss or reduction of the sense of pain without loss of consciousness. Aspirin and acetaminophen are examples of analgesics.
  • Sedation is a state of reduced anxiety, stress, or excitement brought about by the administration of a sedative agent or drug. Sedation is often used before a general anesthetic is administered in order to calm a pet.
When is anesthesia used?
Veterinarians use anesthesia in two broad cases:
  • When a procedure involves pain that is more than quick, minor discomfort, e.g., surgery -- whether planned or emergency -- and dental procedures, such as cleanings and extractions.
  • During procedures -- even painless ones -- that require the pet to remain motionless. Unfortunately, you can’t tell your pet to “keep still” and expect it to obey.
Common non-surgical procedures requiring the use of anesthesia include the following:
  • Imaging studies, such as X-rays, CT scans, and MRI. (Sometimes sedation alone -- without general anesthesia -- may be sufficient to calm the patient and keep it still.)
  • Endoscopy
  • Radiation treatments for cancer
Preparation for surgery

Unless your pet is having an emergency procedure, your veterinarian will conduct a thorough examination before the day of surgery. Depending on the age of the animal, its medical history, and its general state of health, other tests such as X-rays, ECG, cardiac ultrasound, and blood work may be performed. The results of that examination and any necessary tests may affect the veterinarian’s choice of anesthetic agent, as well as alerting her/him to any potential risks of surgery.

General anesthesia: what actually happens?

Before general anesthesia is administered, the patient is usually premedicated with a sedative so that it feels calm and relaxed. Use of a sedative in an excited or frightened animal may allow for less general anesthesia to be used and will usually make recovery from anesthesia a smoother process.

In most cases, an analgesic is also administered along with the sedation. This reduces post-operative pain and makes recovery less traumatic.


The process of producing unconsciousness through general anesthesia is called “induction.” Induction is usually brought about by the use of a short-acting intravenous (IV) anesthetic agent. After induction has been achieved and the animal is unconscious, a soft plastic tube (endotracheal tube) is inserted into the windpipe (trachea) and is connected to a machine containing anesthetic gases and oxygen.

Although pet owners are often uncomfortable with the thought of a tube being inserted into their pet’s trachea, it is important to remember that the pet is completely unconscious when this is done. In addition, having the tube in place is a key safety measure because it enables the surgical team to provide breathing assistance to the patient if that should become necessary during surgery.

The endotracheal tube also protects the patient from accidentally inhaling stomach contents into the airways during the procedure.

During the procedure

If your pet has received general anesthesia, its vital functions, including heart rate and respiratory rate, are carefully monitored throughout the duration of the surgical procedure. This close monitoring enables the surgeon to intervene quickly if there are any complications.

The general anesthetic drug is continuously administered during the procedure in an amount necessary to maintain the desired “depth” of anesthesia. The correct depth depends on the surgery being performed and the patient’s particular response to the anesthetic being used.

The surgical team will evaluate such indicators as reflexes, muscle tone, and changes in vital signs during surgery and increase or decrease the dose of anesthesia as necessary in order to maintain the correct depth of anesthesia.

What are the risks?

Although no medical procedure or drug is without risk, modern methods of veterinary anesthesia are highly sophisticated and generally safe.

We sought the opinion of an expert in the field: Diane Wilson, DVM, MS, MRCVS, ACVA (Diplomate), a board-certified veterinary anesthesiologist with Med-Vet, a veterinary emergency practice in Worthington, OH. Wilson said: “The risks of anesthesia are much less than they used to be. There are more and more board-certified veterinary anesthesiologists and veterinary technicians with specialized training in administering anesthesia. In addition, new, safer anesthetic gases are in use, and our ability to monitor patients during surgery is much improved.”

Questions to ask

Modern methods of veterinary anesthesia make surgery of all kinds safer for our pets than ever before.

If your pet will be undergoing surgery or some other procedure requiring the administration of anesthesia, don’t hesitate to discuss your concerns with your veterinarian. In addition to any questions you may have, here are some others you might want to ask:
  • Who will be administering the anesthesia and monitoring my pet during the procedure?
  • How long will my pet have to remain in the hospital after surgery?
  • Does this veterinary facility has qualified overnight monitoring of post-surgical patients?
  • What will be done to keep my pet comfortable and free of pain in the post-surgical period? 
Your veterinarian will be happy to address these and any other concerns you may have. While the risks of anesthesia can’t be eliminated, you should not allow your concern over those risks to dissuade you from obtaining needed treatment for your pet.


  1. GREAT information (as always) Jana! Thank you for this article

    I think too many pet parents avoid necessary procedures (ie., dentals) because of a fear of anesthetic. Twenty years ago I could understand their concern but these days most hospitals follow strict anesthetic protocols before, during and after surgery. These protocols help drastically minimize the risks associated with anesthetic. Pet parents should check that their clinics perform blood work prior to anesthesia and use IV fluids during the procedure to maintain hydration and blood pressure.

    1. Knowledge, usually, helps to mitigate fear. Anesthesia protocol has certainly improved. I don't rush into procedures that require anesthesia but when they're needed they need to get done, right? I also like to combine things where possible.