Using prednisone for dog lymphoma too soon 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, and also before you have a confirmed lymphoma diagnosis.
Why? This common steroid is used in lymphoma protocols … and can also interfere with lymphoma protocols.
This is a little weird, so let me explain.
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. It’s a great anti-inflammatory for use with itchy skin, allergic reactions, and allergies.
Prednisone is also immunosuppressive at higher doses, which means it is great for immune disorders. That’s why it is used for things like inflammatory bowel disease and immune-mediated diseases like anemias and platelet disorders.
Prednisone is also part of most lymphoma treatment protocols because prednisone actually kills lymphoma cells. In fact, it can be a standalone treatment: if a pet Guardian decides against chemo, I recommend prednisone. Survival times for lymphoma without chemotherapy treatment are about one month, but using prednisone increases median survival times about two to three months, with about 50% response rate.
Sounds great, right? Why not start prednisone for dog lymphoma right away?
Mistake: Using Prednisone Right Away
It’s tempting for a lot of general practice veterinarians to start dogs on pred immediately if they see lymphoma on an aspirate. But this is a mistake if you are going to consult with an oncologist or use chemotherapy. Why?
Our current lymphoma protocols can be very effective. The median survival time for dogs receiving chemotherapy is thirteen to fourteen months. Compare that to one month with no treatment, or two to three months with prednisone alone, and you see why we oncologists are keen to use UW CHOP for your dog’s lymphoma.
They are definitely worth a chance if you choose chemotherapy.
Which means you should avoid the use of prednisone for dog lymphoma until AFTER you have confirmed the diagnosis, and ONLY if your oncologist prescribes it.
Why? Prednisone complicates diagnostics, and interferes with chemotherapy treatments. Let’s look at diagnostics first.
Prednisone for Dog Lymphoma Complicates Diagnostics
If you start prednisone (often shortened to “pred”) before we complete other tests like chest X-rays and abdominal ultrasound, those tests will now be less accurate. Why? Because you’re already treating cancer, so we don’t know as much about the illness your dog has.
Staging Lymphoma Is Affected
For example, if your dog is already on prednisone before a liver and spleen ultrasound, that ultrasound image is not very useful. We can’t tell if lymphoma has invaded those organs or not. The lymphoma may have been there before the prednisone, or may not have been. We just can’t tell.
Why is this important? Well, how much lymphoma has spread tells us what stage cancer we’re dealing with. And knowing the stage helps us to determine treatment, monitor response, and make a more accurate prognosis about the probable outcome of treating your dog.
Side Effects Are Affected
Here’s another fact: if your dog is on prednisone before we finish testing and staging his or her cancer, he or she is probably having few side effects from the lymphoma. Of course, that’s great for the dog’s comfort, but if symptoms and side effects pop up later after we start treatment, it may be difficult for me to distinguish whether those are due to the chemotherapy or to the cancer itself. (This is one reason to see an oncologist RIGHT AWAY if you find out your dog has lymphoma!)
SubType Diagnostics Are Affected
And another thing: prednisone can affect the test for the lymphoma phenotype, also known as the subtype. There are two subtypes of lymphoma: B-Cell, which means the lymphoma is in the B-cells, and T-Cell, which means the lymphoma is attacking the T-cells. Whether your dog’s lymphoma is B-Cell or T-Cell matters, a lot: B-cells usually respond better to chemotherapy and have a longer survival time. If I can’t tell whether your dog has B-Cell or T-Cell lymphoma, I’m not going to be as accurate in my prognosis, and it will be harder for you to make a decision about whether and how to treat.
For this reason, I don’t test for the subtype if a dog is already on pred and the lymph nodes are already in remission. The subtype 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.
Lymph Node Aspirates Can Be Affected
In order to confirm your vet’s diagnosis, I take an aspirate of a lymph node. But if your dog is on pred, and the aspirate is inconclusive, we have to delay confirmation while I re-aspirate or actually biopsy a lymph node to confirm the diagnosis. This happens often when a dog has already started on prednisone before they arrive in my office.
Once again, starting prednisone before getting a diagnosis confirmation, makes getting a diagnosis a challenge.
And if diagnosis is a challenge, and I don’t have the good data I need to make a protocol choice, it can interfere with treatment.
It’s Harder to Choose a Chemo Protocol with Confidence
Knowing all of the above, particularly the B-Cell or T-Cell subtype of your dog’s lymphoma, 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 the protocol has to be adjusted, and our expectations have to be adjusted, too.
I’m really flying blind — and therefore less accurate in terms of my advice — if your dog is already on pred and we can’t test for the subtype.
So, we’ve established that prednisone can really complicate diagnostics. But what about what it does to chemo treatments themselves?
Prednisone Used Too Soon Can Trigger MDR
Unfortunately, steroids like pred potentially make treatment with chemo less effective.
Prednisone can trigger a mechanism in the cells 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 for any cancer.
There’s a bunch to know, but in short, MDR is something some cancer cells can do to evade chemotherapy. Basically, some sneaky cells turn on pumps that literally eject chemotherapy agents OUT of the cell. No matter how much chemo we throw at them, they just keep throwing it back.
For more helpful tools and information, get a copy of the Dog Cancer Survival Guide
MDR can develop during normal chemo treatments, but just using prednisone alone can also trigger MDR.
As you can imagine, dogs with lymphoma who have MDR have a much worse prognosis than those who don’t.
The use of pre-treatment prednisone has been demonstrated to be a strong negative-predictor for dogs with lymphoma. In plain English: dogs who are on pred before they start chemo don’t respond as well.
Bottom Line: Wait to Use Prednisone for Dog Lymphoma
Lymphoma is a very aggressive dog cancer, and the pressure to start treatment right away is (and should be) enormous.
Every day you delay treatment is a day lost, and time is really short with lymphoma. (Most cancers do NOT have such tremendous pressures!)
However, that urge to treat does NOT mean you should start prednisone immediately.
Wait to see what the test results are. That way, you can choose from ALL of the relatively good options we have for treatment.
Jumping right in with prednisone can take options off the table.
Live longer, live well,
Sue Ettinger, DVM. Dip. ACVIM (Oncology). Dr. Sue is a boarded veterinary medical cancer specialist. As a Diplomate of the American College of Veterinary Internal Medicine (Oncology), she is one of approximately 400 board-certified veterinary specialists in medical oncology in North America. She is a book author, radio co-host, and an advocate of early cancer detection and raising cancer awareness. Along with Dr. Demian Dressler, Dr. Sue is the co-author of The Dog Cancer Survival Guide: Full Spectrum Treatments to Optimize Your Dog’s Life Quality and Longevity.
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