Understanding 'adverse anesthetic events' in pets (Part 2: Twelve steps to avoid them)

Patty Khuly, DVM
November 17, 2008
Share this:

It’s well known that precautions can be taken to mitigate the potential havoc anesthesia can wreak on any given patient, human or animal. In human medicine, safety measures are governed by scrupulous standards, which are the result of meticulous research.

The veterinary profession has learned a great deal from its human counterpart, given that science in the realm of animal-specific anesthesia has never been as well-funded as on the human side. Yet anesthesia in some ways is little different in animal patients than it is in humans.

That’s why so it’s no shock to learn that much of what we know about veterinary anesthesia comes from human models (as is the case in so many other areas of vet medicine). It’s not a perfect route to a complete understanding of what animals need…but it helps.

In particular, the care human medical practitioners take to prevent “adverse anesthetic events” (discussed in yesterday’s post) is analogous to the approach we take to our veterinary patients. Here’s the run-down on how vets play “follow-the leader” when it comes to caring for animals under anesthesia:

1-Physical examination

We veterinarians screen our patients to ensure they’re healthy, taking into consideration that non-routine procedures on less robust patients must be moderated to their specific challenges. Physical examination is the most basic (and in many ways the most important) method of screening patients.

2-Basic labwork

CBCs, chemistry panels and urinalyses, in particular, provide the foundation for assessing our patients’ degree of risk. Here we’re trying to assess a pet’s hydration status, electrolyte balance, basic liver and kidney function, red and white blood cell counts, platelet levels, etc. so that these can be addressed before administering drugs that might challenge a pet suffering any deficiencies in this area.

3-Additional testing

Any significant findings in the above two screening approaches may find us refusing to anesthetize a pet. It’s up to additional testing to better determine the real risks involved. Anvanced labwork, X-rays, ultrasounds and EKGs or full cardiac workups are common follow-ups. CT scans, specialist consults and MRIs may also play a role for the luckier, well-heeled pets whose owners can afford to spring for investigation into specific problem areas pre-procedurally.

4-Intravenous catheterization

No, not every vet will require every patient to sport an IV catheter throughout a procedure. But you should now that it’s always safest. In fact, it’s one of the easiest ways to make your pet safer during any given procedure, no matter how routine. If you have the extra $15-$30 to spend, you’ll definitely want to request one.


Fluids can make a huge difference to many pets—especially during longer procedures or when using drugs that may cause drops in blood pressure (a great many of the drugs we use for anesthesia). Again, always safest…with very few exceptions.

6-Warmth and temperature monitoring

Some of our anesthetic monitoring equipment comes supplied with a rectal probe to continuously monitor our patients’ temperature. I’m a big fan of this feature. It’s easy to ignore temperature changes. And drops in temperature during anesthesia can be precipitous. Hot air/hot water pads (or simple, low-tech hot water bottles) can be invaluable, especially for our smaller patients whose temp drops are most likely.

7-Pulse oximetry

This is a fundamental tool, one for which no procedure is too routine to forgo. It’s a blood oxygen monitor and it’s applied to an extremity or tongue to measure the percentage of blood, a value which appears on the monitor’s screen.

8-Heart rate monitoring

This bit of equipment is usually built into the same monitor that reads the oxygen concentration. It beeps reassuringly throughout the procedure while registering the number of beats per minute on a screen.

9-Continuous EKG monitoring

This is another basic tool which may or may not be part of the pulse oximeter and heart rate monitoring equipment. And it’s simple. Just clip the lines onto a pet and watch the screen. It, too, records the heart rate and any vet can see at a glance when scary electronic changes are happening to the heart. This makes it much easier to tailor our drug administration in the event of a cardiac arrest.

10-Blood pressure monitoring

Many hospitals also have this capacity built into the EKG and pulse oximetry system. It can be essential to know exactly where your BP is at during surgery, though it’s a shockingly underused tool in vet medicine relative to the human side of things.

11-Judicious, individualized drug usage

Though you can easily request all of the above from the average vet’s facility, the choice of anesthetic drugs is a far more personal one than most of us want to admit. Most vets stick to drugs they’re comfortable using. That’s because we get used to the kinds of reactions and complications we see with the cocktails we’re familiar with. Ask us to use a drug we’re not experienced or comfortable with and the risks can climb—not exactly the goal you had in mind.

Ideally, you’ll trust your vet on this. If you have profound reservations about certain drugs, however, you’ll want to find a vet who does not use them or can easily shift course to another protocol that he/she deems perfectly acceptable.

Sorry if this section is somewhat lacking, but I’ll plan on writing a longer post on all the anesthetic drugs we tend to use (just as I did for euthanasia a couple months back).


Again, here’s another area where you’ll just have to be comfortable with your vet’s level of experience. Presumably, you’re not even considering an anesthetic procedure at a practice whose vets seem to lack the kind of experience and/or training you require for your pets, right?

But don’t assume that more years in practice equals greater competence in a crisis. Sometimes it’s young vets with a healthier dose of fear at the ready who make for the best practitioners in the case of an adverse anesthetic event.