Should My Pet Have Blood Work?

Blood testing in dogs and cats isn’t simply a case of ‘more is better’. It can be lifesaving but it can also occasionally bring harm. The decision to do it is by no means as black and white as it seems.

I’m going to use the evidence and my experience to help you decide if blood tests are a good idea for your pet. I’ll start by answering the question: when are blood tests useful? Then I’ll discuss the downsides.

How Often Are Blood Tests Abnormal?

The odds are low but definitely not zero. Three recent studies have looked at how often significant abnormalities are found in apparently healthy dogs and cats:

  • 20 out of 1293 young dogs (1.5%).
  • 3 in 100 middle-aged and old cats (3%)*
  • 11 in 406 dogs aged 6 to 9 (2.7%)**
  • 5 in 130 cats aged 6 to 9 (3.8%)**

From this, I roughly estimate that 1 in 70 young animals, and 1 in 25 in middle age, will benefit from blood testing. Tests will be even more useful for:

It’s up to each owner to decide if risks like these can be accepted. Personally, I choose to test my pets from 7 years of age, but I applaud puppy owners who want testing done before desexing. This can act both as a useful check for some congenital diseases and a baseline set of values for future tests.

The most common abnormalities we find are kidney or liver disease. Just like my dog Tinker, they can be treated if found early and modified anaesthetics can still be given safely.

How Much Does Blood Work Cost?

Prices will vary between clinics but these are typical fees in 2019:

  1. Mini-test (up to 7 years old): $87
  2. Full test (over 7 years old): $120

What Are The Negatives Of Blood Work?

Now for the downside. Apart from cost, there are two important reasons why blood testing needs consideration:

Stress & Anxiety

Stress and anxiety need to be recognised with any veterinary procedure. I painfully recall a case where a very educated owner wanted her tiny puppy to have a special blood test. I should have gently explained why it wasn’t a good idea. Instead the poor thing had a terrible experience that could have been avoided. How?

Easy. If I had waited until the day of the anaesthetic I could have taken it with no extra stress. We draw the blood directly from the intravenous line we place before surgery.

Most of the time, dogs and cats tolerate blood testing well, and we encourage you to stay with your pet to offer support. Occasionally the negatives of stress outweigh the positive benefits of testing.  You can usually trust us to advise you on this.

False Positives

Every pet owner needs to know that tests are never 100% reliable. For any single test, there’s a 5% chance of it looking abnormal when it’s actually OK. Once you test 20 values, that number jumps to 64%. The reasons for this have to do with the natural variation that occurs in nature.

When I review any pet’s blood test results, there is almost always something that looks wrong. My job is to separate the wheat from the chaff. Most of the time it’s easy, but every now and again a ‘false positive’ will require extra tests to identify.

It’s not devastating to get this wrong as long as we don’t assume anything without proof. However, it’s always a time of worry for owners while we sort it out.

Is Blood Testing Necessary?

There isn’t one right answer. Each pet owner will have a different attitude to the risks of not testing, the costs and the downsides. Each pet will have a different risk profile depending on their age, breed, tolerance of handling and how much we can learn by other means. In the end, it comes down to a personal choice.

We’ll always be there to guide you and do whatever you ask. Or instead, you can always ask the magic question: “What would you do if it was your pet?”

Have something to add? Comments are welcome below and will appear within 24 hours of lodging.
By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on email and Twitter. The information provided here is not intended to be used as a substitute for going to the vet and is not guaranteed to be accurate. If your pet is unwell, please seek veterinary attention.

*This study also found FIV in 14% and one urinary infection
**This study (in my opinion) over-diagnosed significant problems so these numbers are adjusted by me. I’m happy to discuss my reasoning.

Further Reading

For an in-depth look at everything we check please visit our page on what we test blood for in dogs & cats.

Paepe, D., Verjans, G., Duchateau, L., Piron, K., Ghys, L., & Daminet, S. (2013). Routine health screening: findings in apparently healthy middle-aged and old cats. Journal of feline medicine and surgery, 15(1), 8-19.

Alef, M., Von Praun, F., & Oechtering, G. (2008). Is routine pre‐anaesthetic haematological and biochemical screening justified in dogs?. Veterinary anaesthesia and analgesia, 35(2), 132-140.

Dell’Osa, D., & Jaensch, S. (2016). Prevalence of clinicopathological changes in healthy middle‐aged dogs and cats presenting to veterinary practices for routine procedures. Australian veterinary journal, 94(9), 317-323.

Andrew

7 Replies to “Should My Pet Have Blood Work?”

  1. My dog had surgery last week at the vet.I didn’t give any consent or permission for them to take blood samples. When I went to pick my dog up,they demanded I need to pay the $98 for it,as they did it anyway.I ticked the no box,but the vet changed it to the yes box.

    1. Hi Alison. I’m sorry to hear that – there’s not much you can do if that’s the case. Obviously there’s been a breach of trust and you will be seeking services elsewhere. It would seem unnecessary to do, but you could always photograph a form after you’ve signed it in the future.

  2. My dog is a 13 year old yellow lab who has been epileptic most of his life. His vet would like to do a blood test to check his levels and see if his dose is correct. The last time his meds were reduced he seized so I have no intention of reducing his meds due to his age. And the the fear he could seize and die. His vet has told me that they won’t give him is script for his meds if I don’t allow the blood test. It sounds like extortion to me. What do you think?If I get the meds directly from the vet they charge me $68 if I get a prescription and get them from the pet chemist it’s only $17.99 exactly the same brand, dose and quantity. I get that it’s a business but the price difference can’t be justified.

    1. Hi Lorraine. Phenobarbitone levels are only a guideline, and if the drug is tolerated then it’s not unheard-of to be outside the recommended range. That is the big question: is the drug tolerated? I would consider the blood test to be more useful on this basis as liver damage occurs with phenobarbitone use even after a long trouble-free period. However, in my clinic I am quite happy to discuss the pros and cons of blood tests and let an owner decide. Therefore, you are likely to find other vets who feel the same way about informed consent. Regarding pricing, I am guessing that the $68 covers more than just a prescription – probably a visit for you as well- but if it doesn’t, once again it’s a free-market and you may find another vet doesn’t charge the same. And of course, there are the online pharmacies- I know that plenty of vets don’t like working with them, but plenty of others do.

      1. Thank you for the reply. I still feel that if Bear had a blood test and the results show he has liver damage the vet has said and I quote “ because of his age there is really not much we can do for him” what is the point . He is happy relatively healthy for his age and I take him to the vet a least twice a year for checkups so for the vet to say no blood test no prescription is extortion. And by the way I pay $68 for the tablet plus $70 for the consult. Am I being ripped off. One again thanks for you reply.

      2. Hi Lorraine. Your thinking is the same as mine in that there is no value in a test if its result could not change anything. In this case however, a test showing problems would allow you to use another seizure medication. Of course, these are more expensive so you may say “I wouldn’t use anything but phenobarbitone regardless“ and in that case it’s possible the test result would be meaningless. Not all vets will agree with this approach.
        As for vet pricing, you can see a long article with my views here.

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