What Are Pet Blood Tests For?

You’ve probably noticed how much we like blood tests. Every year when your dog or cat has their annual checkup or when your pet needs an anaesthetic we ask you if you want blood testing.

Is this just over-servicing or are there good reasons to check?

In the end it’s up to you to decide. Once you read Trixie’s story you may see it from our point of view.

Why Do We Do Blood Tests?

trixie at vet

Two years ago when Trixie was ten years old, she came for her annual checkup. She seemed completely healthy but when we asked her owner if she also wanted us to take blood she said yes. Here’s why:

  • The older you are the more can go wrong
  • Dogs age seven times faster than humans; each annual checkup spans seven of our years
  • Dogs can’t complain about feeling sick
  • Good haemoglobin, kidney & liver values are vital for anaesthetics
  • And what most pet owners say: we’d do it for ourselves

What Do Blood Tests Look At?

Trixie’s physical exam was 100% normal but we didn’t stop there. Our nurses do a great job of holding dogs or cats for blood testing, and so the sample was taken without distress to dog or owner.

Although we have our own in-house blood analytical machine for emergency and pre anaesthetic screening, we always send non urgent samples to an external laboratory.

dog blood test

Here are Trixie’s results. I’ve labelled each set of values so you can see what is included in a standard blood test. As you can see, there are a lot of readings taken from a tiny amount of blood.

We can get all of this from 1.5mL of blood. If you look at the second test you’ll see there’s even more. Sometimes I stop to remember how amazing this is.

As you can see, each value is reported with the normal range for that parameter. As you can also see, there are some abnormalities.

The job of the vet is to sort the wheat from the chaff. There are always spurious or irrelevant abnormalities. In this case, though, you can see that no-one would look at those liver enzymes and think they are OK.

Next problem:

What Happens With Abnormal Blood Results?

The first thing you need to know is that we will always call you to discuss blood results, whether they are normal or not. If you don’t hear from us within two days, check that we’ve got your best phone number, because you can bet we’ve tried.

Most of the time, abnormal results don’t give us a diagnosis. We find that something isn’t working properly or that an organ is in trouble. We still need to find out why.

Typical blood test
Trixie’s second blood test results

Most abnormal results will result in us asking for further specific testing. In Trixie’s case, we started with a second blood test for Cushings Syndrome (which was negative), and then recommended an ultrasound examination.

The ultrasound showed a large mass in the liver, but indicated that there was still time to remove it. She had routine surgery to remove the mass inside its liver lobe.

Recently I saw her again and did her annual checkup. That’s her above looking fantastic. No surprises that her owner asked for another blood test. This one is a good example of the minor variations we can safely disregard.

Should My Dog Or Cat Have Blood Tests?

I like to think of blood testing as a fishing trip. You don’t know what you’re going to catch, and often you come back with nothing to show for the effort and cost (around $120 for Trixie’s for example). Read here how often pet blood tests are abnormal.

It’s a gamble being played with very high stakes. If Trixie didn’t have her routine blood test we would never have found the tumour in time, and she would not be alive and happy today.

Common and important findings include kidney disease, liver disease, chronic pancreatitis and hormonal diseases like overactive or underactive thyroid, diabetes or cushing’s syndrome. All of these can be managed if we discover them in time. Many of them also affect how your pet copes with an anaesthetic.

Most of the time, blood testing will not be this dramatic, but we regularly see stories like Trixie’s. In the end, we will never tell you you should get blood testing done. It’s always your choice and we respect that. But I’ll bet there aren’t many vets who don’t do it for their own animals.

By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!

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