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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

The Oncologist’s Perspective on Chemotherapy and Low White Blood Cell Counts: Part 2

Updated: May 3rd, 2019


There are specific tests oncologists use for white blood cell counts before, during and after chemotherapy. Find out what tests your dog has to have to stay healthy during treatment.

As discussed in Part 1 of this series, chemotherapy can really affect (destroy) white blood cells, particularly the infection-fighters called neutrophils. Let’s look more closely at what tests oncologists use for white blood cell counts.

Why So Many Tests??

Oncologists monitor the white blood cell count closely and often!  Remember, this is important because this is one of the main ways we decide the dose to use in our next treatment.

Neutrophils, the white blood cell we are really concerned about, only lives 18 to 24 hours in the bloodstream. That means that yesterday’s test is no longer accurate. And a complete blood count (CBC) from a few days ago or last week is truly not helpful. The neutrophil count changes daily. We simply have to keep running those tests.

Test White Blood Counts Before Chemo …

The white blood cell count needs to be checked the day of chemotherapy treatment with a CBC, which is a very routine test. The veterinary tech will take some blood from your dog, and it will be analyzed by special equipment. Most hospitals have the ability to run this test right away, so most oncologists run it while you and your dog wait.

… And Test White Blood Counts After Chemo

Similarly, I recommend checking what is called a nadir CBC after chemotherapy treatment. Nadir is a fancy word that simply means “lowest.”

The chemo agents don’t necessarily destroy white blood cells immediately on contact. It can take a while. For most chemotherapy drugs, it takes about seven days to see just how low the white blood cells get. We call this day the “nadir.”

That’s why I have my patients come in on the 7th day after chemo, to make sure the WBC is not too low.

For drugs that have different nadirs, we schedule that test for a different day. For example, the nadir for carboplatin is 10 to 14 days after treatment. When I give carboplatin, I schedule the nadir CBC during that window, because checking on day seven is inaccurate and a waste of time and money.

And yes, I test on the nadir day even if the dog is acting normal.

Temperature Matters

Most owners are surprised to find out their dog has a low white blood count (WBC), or neutropenia, at the nadir appointment. That’s because dogs don’t really behave differently when they have a low WBC. Unless they have an infection, they look totally fine.

And they usually are, because white blood cells typically recover really quickly, within a day or two. The bone marrow is continuously making new white blood cells. Low levels don’t harm a dog — as long as there is no infection.

That’s why I also take your dog’s temperature during the nadir appointment, to see if there is an underlying infection we don’t see yet.

Normal Temperature = Good

If the WBC is low, but the temperature is normal, and the dog is feeling well, that’s good news. I just prescribe oral antibiotics to prevent infection and send the dog home.

Elevated Temperature = Worry a Little

If the white blood cell count is low AND your dog has a fever, and especially if he or she is not feeling well, that’s a different story. Then, your dog might need to be admitted for intensive care – typically IV fluids and IV antibiotics.

Editor’s Note: Dr. Sue discusses sepsis (a systemic infection) in Part 3.

Get a copy of the Dog Cancer Survival Guide, plus all 47 mp3 seminars, for more information on how you can help your dog with cancer.

Preventative Antibiotics

Some chemotherapy drugs are more likely to cause a low white blood cell count at the nadir. For these drugs, I often send a dog home with prophylactic (preventative) antibiotics the first time the drug is given. I routinely do this with Lomustine (CCNU), carboplatin, and sometimes Adriamycin (doxorubicin). Those are the biggies.

Planning Future Doses

Here is another reason to test the WBC at the nadir, even when your dog is acting normally:

If the white blood cell counts are low at the nadir, future chemotherapy doses should probably be adjusted.

We want to give the biggest dose we can that doesn’t lower WBC too much.

And/or, we want to get those prophylactic antibiotics on board right away, with the next treatment.

By testing at the nadir, we know how your pup is responding, and we can adjust the dose and/or make sure antibiotics are used next time.

I know you’re wondering why we don’t prescribe prophylactic antibiotics all the time. The answer is simple: after decades of using antibiotics, we now know that using them unnecessarily is not a good idea. Antibiotic resistance is an issue, and antibiotics can cause GI upset themselves. So I like to use them only when necessary.

What Can Be Done To Correct Low White Blood Cells?

As I mentioned above, the bone marrow keeps churning out white blood cells, and within a few days of chemo treatments, the recovery has already begun. Rarely, we will use WBC stimulators like Neupogen to stimulate the bone marrow.

Remember, the goal of all this is to maximize chemotherapy’s efficacy (kill cancer cells) and minimize the risk of side effects and infection for your dog.

In my next article, I will discuss infections and sepsis that result from neutropenia (chronically low neutrophil counts). I will also discuss why dogs that get low WBC counts may actually do better on chemotherapy.

Until then, be sure to check out more about chemotherapy and its side effects in the Dog Cancer Survival Guide.

All my best,

Dr. Sue Cancer Vet

Also, See:

The Oncologist’s Perspective on Chemotherapy and Low White Blood Cell Counts: Part 3

The Oncologist’s Perspective on Chemotherapy and Low White Blood Cell Counts: Part 1

Leave a Comment

  1. Elza Mocny on July 10, 2019 at 9:54 am

    My 13 years old shi tzu has very high count of bastonets and segmented…it is just the contrary of what you are approaching here. Can you say something about high count of this kind of white cells?
    My name is Elza Mocny. I live in Brazil in the northern region and her oncologist is in Sao Paulo, southern area, accessible only by airplane so it is hard for us to be doing all this tests even though she has been seen by a cardiologist vet, her forever vet. Recently I went to US where I got apocaps. We just started her on Apocaps.
    Thank you

    • Molly Jacobson on July 10, 2019 at 11:15 am

      Hi Elza, thanks for your question. I’m not a veterinarian, just a layperson and the editor of the book. However, I know that elevated white blood cell counts is a symptom, not a specific disease. It might be due to several different causes, so figuring out which one is sort of the mystery for your vet to solve. In general, an elevated white blood cell count means the immune system is working hard to address an issue. Sometimes it’s fighting an infection, or inflammation, or an allergy. Trauma and stress can also cause high blood cell counts. (I personally had a really high WBC on labs a couple of months ago but it was absolutely due to emotional stress, not illness!) You don’t say whether your dog is on chemo or not, but this article is specifically addressing how chemo tends to lower white blood cell counts, thereby suppressing immune response. In your dog’s case, the immune system is stimulated for some reason. You also don’t say what kind of cancer your dog has, but there might be a connection there, too. Perhaps this is not unusual for your dog’s type of cancer. Your vet may have insight into why that might be, so definitely ask!

  2. Rachel Brown on December 29, 2017 at 4:21 pm

    Our 4 year old Jack Russel / Maltese dog had her leg amputated due to sarcoma on her hip. Her leg was taken before the cancer decided what type it wanted to be?? Don’t quite understand that but anyway. She is on a low dose chemo capsule given at home. Her and her two year old kids run outside feeely in the yard. My question is, if we don’t catch mom pooping, and one of the kids eat it, could this make the kids sick? Thank you!!
    On a lighter note, you notice we call them kids. That is what they are, my grand kids. While out shopping, I asked my daughter if she shut the kids in her room before she left the house as we had to keep them separate from mom after the surgery. The cashier looked at us horrified!!! I then realized what I said and quickly explained that when I said kids, I meant dogs, not actual children!! She laughed and said oh my goodness, I thought you meant real children! I said to my daughter, no more calling them the kids in public!!

  3. Susan Kazara Harper on June 1, 2015 at 4:56 pm

    HI Betsy, Oh goodness, please don’t jump on the lymphoma wagon just yet. There are all sorts of reasons for these symptoms and many are very less threatening. Did she have any swollen glands? Your vet is likely ruling out infections etc., particularly with a fever Ask what the possibilities are and get through this first stage of helping her feel better. We’re all rooting for you both.

  4. Betsy on May 31, 2015 at 4:22 pm

    My dog went to the hospital today because she felt warm was lethargic and wasn’t eating for two days. She had a fever of 106.3
    The vet started her on fluids and is keeping her overnight for testing. She just called and told me she has low white blood cell counts. They will be doing further tests. My dog is a two year old miniature schnauzer. Do these sound like lymphoma symptoms?

  5. Susan Kazara Harper on June 22, 2014 at 11:24 am

    Hi Sam, You don’t say how old your dog is, but I know this is very distressing for you. My best recommendation is to ask to be referred to a specialist vet, or go out yourself and find a vet from whom you can get a second opinion. You have the right to do this, and your own vet will hopefully want you to get some answers. No one is an expert in everything. Be polite and courteous with your vet’s office, and you will need to ask for a copy of your dog’s records. Research vets you can get to, then I suggest you phone the offices, explain briefly what your dog is going through and that you are looking for someone with experience with this type of condition. Good luck. I know this is tough. Your pup is relying on you, and I know you’ll find a professional who can help.

  6. Sam on June 16, 2014 at 5:13 pm

    My dog miniature poodle and I’m quoting the veterinarian “white blood cells are almost nonexistent”. We have been doctoring with our dog since he has been two months old. He’s been on prednisone, atopica and tremadol since two months old. Sometimes the red cells are extremely low. We had a bone marrow test with the hope that would give us some clue. It was unremarkable. He’s had all kinds of tests for parasites nothing. About every four months he gets a fever and goes on antibiotics. Why can’t someone tell us what is causing this? We tried to ween him off the prednisone because of his liver but he became very sick and had to be started back on it. Please help.

  7. Heather on September 10, 2012 at 8:40 am

    Is there anything I can do to help my dog’s WBC during chemo?

    • Dr. Susan Ettinger on September 12, 2012 at 3:50 pm

      Good question, but there is no specific medication or supplement to prevent low white blood cell counts. And when they do get low, they typically rebound on their own quickly within a few days. The bone marrow is amazing at making new ones an getting them into circulation. So we typically just monitor, adjust chemo dosages to prevent them from getting too low, and delay chemo when needs. Hope that helps!
      All my best, Dr Sue

  8. stephen fox on January 23, 2012 at 2:27 am

    Dear Dr. Dressler:

    I have lost several dogs to cancer which may be more prevalent here in New Mexico, starting with skin cancers that turn into melanoma. My 15 year old male has an acorn sized lump on his throat, which Vets have said in the past was most probably benign.

    Without going to the horrible expense of a biopsy, fine needle aspiration (for which Santa Fe vets charge at least $300), and related lab work, and without stressing out this old guy, is there any way of determining without lab work if and when it might have become malignant?

    Thanks for your efforts for dogs avoiding cancer, and I am grateful for your time in answering this question, now or later!


    Stephen Fox
    New Millennium Fine Art
    Santa Fe, New Mexico

    505 983-2002

    • Dr. Demian Dressler on January 25, 2012 at 11:46 am

      Dear Steven,
      you can’t tell for sure if a growth is malignant without a specimen but you can make an educated guess. Wny don’t you shop around and see if you can get a less costly aspirate done?

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