Pre-anesthetic blood testing: this is why your pet needs it.

( 5 mins read)

In a previous article, “The importance of blood work for your pet”, I discussed how routine blood work could be used to create wellness profiles and watch for trends in your pet.

I want to now turn to the importance of having blood work before any surgery your pet may be having. We call that pre-anesthetic blood work.

Veterinarians administer anesthetics for elective surgeries and non-elective surgeries. Elective surgeries are planned and often are done on pets with no apparent health problems. The classic example is your puppy or kitten coming in for a spay or neuter.

Emergency surgeries may need quick reaction time, but blood work before the surgery is still vital.

The main reason is to do pre-anesthetic bloodwork to ensure everything is all right with the animal before surgery. The results can be shocking! I've seen animals that look completely fine and show no signs of illness, but their blood work reveals something completely different.


I want to share an example of a situation early on in my career as a veterinarian which solidified how important pre-anesthetic blood work is. Now, I recommend it for every pet going under an anesthetic.

The story begins with a beautiful six-month-old male cat who came in to be neutered. Neutering a male cat is one of the most straightforward surgeries veterinarians perform. Those experienced at it can get it done in very little time, so it is not a considerable anesthetic risk. In this procedure, animals are not under the anesthetic for very long.

Nevertheless, all anesthetics carry a risk, and so does the surgery. You will definitely see what I mean in this example. The first thing we did was take blood from the cat, put him in the back of the clinic, and let him relax while we ran the blood results. This only took about an hour because we had an in-house blood machine. For those of you who listened to my first podcast where I talked about being an early adopter, I invested in an in-house blood machine for my practice because I knew that I could get blood results back faster than anything I could send out to the lab.

We got the blood results back, and I was in shock! This cat's platelet count was one, and the normal reference range is 100 to 500. I will say that I've never seen a platelet count that low. For those of you who are not familiar with what platelets do, they are involved in clotting our blood. Even a minor cut can turn into a significant bleeding episode without platelets. As my story continues, I will tell you that I didn't panic yet because I have seen low platelet counts in many situations when I’ve taken blood. Sometimes the blood accidentally clots within the tube. To explain, when we take blood to run platelets, we take it in a tube where the blood is not allowed to clot. When the blood accidentally clots, the platelets get used up, which gives you a low platelet count and an inaccurate reading.

So, we purposely put it in a tube that doesn't allow it to clot to measure the total number of platelets. Clear as mud? Don’t worry; I’ll get on with my story! When I saw the results from this little kitten, I was a little bit nervous. I needed to double-check the numbers. The first thing involved was taking a drop of the blood and putting it on a microscope slide to see if I could see any platelets.

If I could see them on the slide, I would probably attribute the low platelet count to a machine error. But when I looked at the slide under the microscope, I couldn't find a single platelet. I'm not going to lie; I was a little nervous at this point. My next move was to cancel the surgery and to take another blood sample and send it off to the lab, where we would get a result in 12 to 24 hours.

When they brought the cat back to the table to take some more blood, I noticed something shocking. There was a huge blood blister right where we had previously taken the blood. After we take blood from any pet, we usually put pressure on that area for a significant period so that they don't develop blood blisters. It's no different than when we go to the lab and have our blood taken, and the medical technician or nurse asks us to apply pressure to that area. So, finding a blood blister after taking blood is very uncommon in a normal pet.

It turns out this little cutie was far from normal! We got the blood results back the next day, and the platelet count was two. Although this is double, it sure was far from the norm, which, to remind you, is 100 to 500.

To make a long story short, this cat was born with a congenital disease where he couldn't make platelets. I chose this story to illustrate how important it was that we ran pre-anesthetic blood work. We were doing an elective surgery on a kitten that seemed very healthy but wasn’t.

If we had just done the surgery without knowing, he could have bled uncontrollably during the procedure and possibly died. It makes me shudder every time I think of this story.

Unfortunately, this cute little kitty didn't live past two years because he had other complications from his bleeding disorder later in life. This condition is extremely rare, and I've diagnosed it only once in my entire career.

While this might seem like an extreme case, I can cite many examples of times when I've delayed or even cancelled surgery because of abnormal results on a pre-anesthetic blood profile.


When I first started offering pre-anesthetic blood work to my clients, it was an option so they could choose whether to do it or not.

After a few more cases with atypical results, I solidified my conviction of how vital blood work is. I started to make pre-anesthetic testing mandatory. Many veterinarians today still offer pre-anesthetic blood testing as an option.

I encourage everyone to understand the risks when you have an elective or non-elective procedure done on your pet. Please consider how crucial pre-anesthetic blood testing is to help give your veterinarian all the information they need to perform the procedure.

It’s an excellent way to play a role in providing the best care you can for your pet.

Don’t forget to check the full podcast episode in which Dr. Mike provides detailed content about this subject by clicking here.


Dr. Mike

Veterinarian and Pet Wellness Advocate
Fear-Free Certified Elite Level practitioner.
His mission is to encourage pet owners to welcome the responsibility of providing their pets with the very best care possible.