Pet Columns, Office of Public Engagement, College of Veterinary Medicine at the University of Illinois at Urbana-Champaign

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Tests Help Ensure Pet's Safety During Surgery

Pet Column for the week of November 4, 2002

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Jennifer Stone
Information Specialist

Neutering or spaying a pet seems like such a routine event that people often forget that any surgery involves a certain amount of risk. The goal of the veterinarian is to reduce the risk as much as possible to ensure that the pet wakes up from surgery healthy, happy, and ready to go home. This is why a pre-anesthetic blood screening before any surgery is essential.

Dr. Rhonda Schulman, a veterinarian at the University of Illinois Veterinary Teaching Hospital in Urbana, says pre-anesthetic blood screening before any surgery is important. "While most healthy animals are at minimal risk for complications during an elective surgery such as a neuter or spay, there is always the chance that an animal might have an underlying problem that might not manifest itself until the animal is put under anesthesia. Surgery is not a good time to discover that there is a problem."

Many veterinarians may recommend that a minimum blood work database be run before surgery to check for abnormalities in kidney and liver function. Many drugs used for anesthesia are metabolized by the liver and excreted by the kidneys into the urine.
If one of these organs is not working properly, the animal may not wake up for a long time after surgery because its body cannot get rid of the drug. If the kidneys are not working, then the drug may stay in the bloodstream because it is not being excreted into the urine. If the liver is not working properly, the drug may not be broken down and may continue to affect the animal long after surgery is over.

"This is just one example of a complication that could arise during surgery if there were some unknown underlying problem," says Dr. Schulman. "Checking for these problems in advance can help to avoid major complications during surgery."

Often, when abnormalities are found on the pre-anesthetic blood screening, the surgery is still performed as planned, but certain changes may be made to ensure the safety of the animal under anesthesia. "Most often, the changes that are made to the surgery are changes in the selection of the drugs," says Dr. Schulman. "For instance, if an animal has renal (kidney) dysfunction, we might choose a drug that is not excreted by the kidneys."

Sick animals require a more thorough pre-anesthetic evaluation than do healthy ones. "In the case of animals that have pre-existing conditions, we will do more thorough diagnostic testing to make sure that the anesthesia does not exacerbate the condition or cause some other crisis during the surgery," says Dr. Schulman. "This way we can tailor the anesthesia to the special needs of the patient.

"If your pet is having an elective surgery such as a spay or neuter and your veterinarian gives you the option of doing some pre-anesthetic bloodwork, it is always best to go ahead and do it," says Dr. Schulman. "The odds of something happening during surgery may be small, but if there is an underlying problem and something goes wrong during surgery the results could be catastrophic for your pet.

It is worth a few extra dollars to achieve a little peace of mind."
If you have any questions regarding pre-anesthetic testing, please contact your local veterinarian.