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Most veterinary hospitals now recommend pre-operative lab work for pets undergoing general anesthesia. It’s the standard of care these days, but veterinarians still get a fair amount of push-back from owners who don’t understand the importance of these tests.

The complaints I’ve heard the most frequently tend to fall into two categories:

1. "But Rascal is only 6 months old and has been healthy her whole life. Why should I have to pay an extra (insert dollar amount here) for testing that will surely be normal?"


2. "But Siegfried just had blood work, why do we have to run it again?"

I get it. I’m frugal and hate the thought of paying for something that isn’t really necessary, but pre-anesthetic lab work is really no place to scrimp.

Let’s look at a typical example that elicits the first argument — a young animal undergoing an elective procedure (e.g., a spay or neuter). Yes, the chance of a problem being detected on pre-operative screening is small, but not negligible. Here’s just one example I know of: a five month old dog scheduled for a neuter that was found to be in the early stages of renal failure and died a month later. What a tragedy for all involved had that dog undergone surgery.

In the case of a young pet, pre-anesthetic testing does not have to be involved or expensive. One of the most progressive clinics I’ve worked for was "okay" running only a packed cell volume (checking primarily for anemia and evaluating the color of the serum for diseases that affect the liver or red blood cells), total solids (looking mostly for infection or protein-losing diseases), and an AZO stick (a quick check of kidney function) in these individuals and proceeding if all was normal. I believe the fee for a PCV/TS/AZO was only $15, and this was in a part of the country with an exceptionally high cost of living. These simple tests require just a few drops of blood and would have picked up the kidney failure in the aforementioned dog.

For owners who chose more in depth testing, this clinic would run a complete blood count (CBC) and either six or twelve blood chemistry parameters with electrolyte levels to give us a better look into whether or not a pet could be suffering from anemia, dehydration, infection, parasitism, bone marrow dysfunction, liver disease, kidney disease, etc. Additional tests might also be recommended based on a pet’s breed and history.

The question of when "old" lab work is too outdated to be useful has to be answered on a case by case basis. My general rule of thumb is one month — as long as no relevant abnormalities were found on the previous tests, we’re dealing with a pet without a history of health problems, and the patient’s physical exam and history immediately prior to anesthesia are normal. Otherwise, I want the most up-to-date results possible. Many illnesses that veterinarians see on a day-to-day basis can go from undetectable to potentially deadly (particularly when combined with surgery and/or anesthesia) over the course of just a few weeks.

Pre-anesthetic screening is a life-saver. Don’t put your pet’s health at risk by opting-out.

Dr. Jennifer Coates

Image: Ivonne Wierink / via Shutterstock

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