Featuring Demian Dressler, DVM and Susan Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide.
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Common Cancer Mistake: Starting Your Dog with Lymphoma on Prednisone Too Soon

Using Prednisone to Treat Dog Cancer

Should you start your dog with cancer on prednisone right away, or wait until you’ve staged the cancer and explored other treatment options?

It happens all the time, so don’t beat yourself up if you’ve done it. But if you can, avoid the use of steroids (such as prednisone) before chemotherapy, or before the diagnosis of lymphoma is confirmed.

Now, I’m not bashing prednisone across the board. Steroids are used for many things in veterinary medicine. For example, your dog has probably been on prednisone before. It’s great anti-inflammatory, and it is used for itchy skin, allergic reactions, and allergies. Prednisone is also immunosuppressive at higher doses, so it is used for things like inflammatory bowel disease or immune mediated disease  like anemias and platelet disorders.

Prednisone is also part of most lymphoma treatment protocols, because it actually kills lymphoma cells. It can even be taken as a standalone treatment for lymphoma — if a pet Guardian decides against chemo, I recommend they start prednisone. That’s because survival times for lymphoma without chemotherapy treatment are about one month, but prednisone will increase that to about two to three months with about 50% response rate. Sounds great, right? Why not start it right away?

There are two reasons.

Reason One to Wait to Start Prednisone: Steroids Complicate Diagnostics

If you start prednisone (often shortened to “pred”) before we complete other testing like chest X-rays and abdominal ultrasound, you are treating the cancer and those tests will now be less accurate.

For example, if the liver and spleen look normal on ultrasound, but the dog is already on prednisone, we can’t tell if the lymphoma was there before the steroid use started. That means that we don’t have a baseline of information to use when monitoring response to treatment. It also means we know less about the illness your dog has. Knowing what stage the lymphoma is in will help me make a more accurate prognosis about the probable outcome of treating your dog.

Another thought: if your dog is on prednisone before we finish testing and staging the cancer, it may be difficult for me later to distinguish whether symptoms and side effects are due to the chemotherapy or the cancer itself.

Prednisone can also affect the test for phenotype, or subtype. In this test, we look to see: is the lymphoma  of the B-cell subtype, or of the T-cells? This information matters a lot, because B-cells usually respond better to chemotherapy and have a longer survival time.

Unfortunately, if a dog is already on pred, and the lymph nodes are going into remission because of it, I will not be able to run this test. This test is the very best predictor we have for lymphoma: it helps us predict both the cancer’s likely response to treatment and the likely survival time we’re working with.

Not only that, but this information helps me to choose which protocol to use. The UW CHOP multi-agent protocol (the best protocol we have) does not work as well for T-cells as is does for B-cell lymphomas.So using it would be less effective in T-cell lymphoma, and I would have to adjust the protocol and the expectations for outcome.

Along the same lines, if the lymph node aspirates are inconclusive (non-confirmatory), I will need to re-aspirate or biopsy a lymph node to confirm the diagnosis. If the dog is on prednisone because we did not wait for diagnosis confirmation, getting a diagnosis becomes a challenge, and I don’t have the good data I need to make a protocol choice.

Reason Two to Wait to Start Prednisone: Steroids Can Make Chemo Less Effective

Steroids potentially make treatment with chemo less effective. Unfortunately, prednisone can interfere with later chemotherapy treatments, and can trigger a mechanism called Multi Drug Resistance (MDR). I cover this at length in The Dog Cancer Survival Guide, because it’s an important concept for you to understand if your dog is undergoing chemotherapy. Basically, MDR is a capacity some cancer cells have to pump chemotherapy agents OUT of the cell. No matter how much we throw at them, they just keep throwing it back.

Dogs with lymphoma who have MDR have a much worse prognosis than those who don’t. This is a very important reason to avoid the use of steroids before chemo starts — they can trigger that MDR. In fact, the use of pre-treatment prednisone has been demonstrated to be a strong negative-predictor for dogs with lymphoma – meaning they do not respond as well to chemo.

Our current lymphoma protocols can be very effective. The median survival time for dogs receiving chemotherapy is thirteen to fourteen months. Giving these protocols a chance — if you choose chemotherapy — means avoiding the use of prednisone.

Lymphoma is a very aggressive cancer in dogs, and the pressure to start treatment right away is (and should be) enormous. The reality is that every day you delay is a day lost to treatment. However, that urge to treat does NOT mean you should start prednisone immediately. Waiting to see what the test results are, allows you to choose from all of the relatively good options we have for treatment. On the other hand, jumping right in with prednisone can take some of those options off the table.

Live longer, live well,

Dr. Sue

About the Author: Susan Ettinger, DVM, Dip. ACVIM (Oncology)


Susan Ettinger, DVM. Dip. ACVIM (Oncology) is a veterinarian oncologist at Animal Specialty Center in New York and the co-author of Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog's Life Quality and Longevity. She blogs about dog cancer at http://DogCancerBlog.com.

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  • Mary

    I’m confused. My dog’s oncologist also said that taking prednisone prior to therapy makes chemo less effective, but used prednisone after chemo was initiated. Are you saying that prednisone at any time during chemotherapy is not a good thing to do?

    Thanks!

    • DrSueCancerVet

      Mary, Sorry for the confusion, but the issue is ONLY USING PRED PRIOR to chemo. Using pred with chemo is not an issue and pred is included in many chemo protocols for lymphoma.
      Wishing your dog a great response to chemo and a long complete remission!
      All my best, Dr Sue