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

What’s My Dog’s Prognosis? When to “Believe” Numbers You Hear from Your Vet

Updated: February 25th, 2019


Dog Bone Cancer Prognosis: Dr. Susan Ettinger looks at two case studies to show how statistics cannot predict how an individual case of canine cancer will turn out.

Once you have heard the horrible news that your dog has been diagnosed with cancer, a lot of thoughts start racing around your head. One of the common questions I get is, “How much time do we have?”

Reasonable question. And yet, despite all my training and experience as an oncologist, it is so hard to answer.

During my residency, I had to learn lots of numbers and statistics related to cancer. I’ve discussed some of the common terms in a previous article, The Oncologist’s Perspective on Statistics: Part Three, where I discuss median survival times, response rates, and metastasis rates. No matter what type of cancer your dog has, knowing these numbers are helpful to know.

But should you “believe” them? If the numbers are in your dog’s favor, does that mean your dog will be in the group of dogs that is “good?” Or if the stats are pretty bad, does that mean your dog will be in the “bad” group? Nope.

Don’t believe statistics. Instead, use them to navigate.

Numbers Are Just Numbers. They Are Not Your Dog!

In that series on statistics, I wrote about how stats are helpful but don’t predict the way individual cases turn out. I bring it up again because two cases this week drove this home, both good and bad.

Today, I’m going to go over a brief overview of stats and then discuss two recent cases of bone cancer (osteosarcoma), to show you just how different statistics can play out in real life.


There are two questions we want to answer by looking at statistics in dog cancer.

  • How does this treatment impact how long your dog will live, and how likely is he to respond to that treatment?
  • What is the metastasis rate for this cancer? In other words, how likely is this cancer to spread?

These are very complicated questions for an oncologist to answer, even when we have “good” data to look at.

Statistics in Prognosis: a Super-Short Overview

Let’s say a dog has a soft tissue sarcoma (STS) and the parents opt for surgery. Afterward, a tumor sample is sent to a pathology lab for examination.

Ten days later, the report says it’s a “low or intermediate” grade soft tissue sarcoma with “incomplete surgical margins.”

It’s a less aggressive tumor, but there were cancer cells on the edge of the sample. This is also called “dirty margins.”

There are probably cancer cells left in the body. This happens because surgeons can’t know they are “getting it all out” just by looking, which is why we want large margins around cancer surgeries.

Unfortunately, in the case of STS, dirty margins make recurrence 10 times more likely.

That statistic is helpful, if grim. If we leave those cells alone, the tumor is almost certainly coming back. That’s why the standard recommendation for low or intermediate grade STS with dirty margins is additional surgery and post-operative radiation if there is a recurrence.

Statistics help us make decisions, but they aren’t laws.

Here’s another statistic about STS that helps us make decisions: the metastasis rate for low or intermediate STS is 10-15%.

In other words, cancer will spread to other areas in one or two dogs out of ten with low or intermediate STS. On the other hand, eight to nine dogs with low or intermediate STS will never see metastasis!

We treat likely metastasis with chemotherapy because it circulates medicine around the whole body, not just where the tumor is. Since metastasis is pretty uncommon in low or intermediate STS, it’s unnecessary in 80-85% of dogs, and we don’t recommend it.

What about high-grade STS? Well, if the pathology report shows a high-grade STS with dirty margins, the situation is different.

The metastasis rate for high-grade STS is much higher: 40%. With four out of ten dogs getting cancer spread, we use chemotherapy to delay that metastasis, plus the extra surgery and/or post-operative radiation.

Whether your dog has STS, OSA, or any other cancer, this book will help. There are seven things that ALL cancers have in common, and most of the strategies in this book address them. That means that the diet, supplements, and lifestyle choices Dr. Dressler and Dr. Ettinger recommend can help ANY dog with cancer!

Statistics are Confusing

That’s a lot of numbers to juggle, and if you’re a little confused, it’s because it’s confusing. It might take you a while to understand your dog’s case stats. That’s totally normal.

Make sure to ask your veterinarian or oncologist to explain the numbers to you. It really helps you to make confident decisions if you know the “why” behind the recommendations.

Let’s look at a couple of real-life cases now. These two cases that involve bone cancer, specifically osteosarcoma. (Osteosarcoma is the most common bone tumor — 85% of dogs with cancer in the bone will be diagnosed with osteosarcoma.)

By looking at these cases, we can see how statistics help, but don’t define, decisions about dog cancer treatment.

Case: Osteosarcoma in Blackie’s Wrist

Blackie is a mixed breed dog with osteosarcoma (OSA) of his left metacarpal bone. This is one of the bones in the paw just, below the wrist or carpus.

After Blackie had his front leg amputation, I met with him and his parents to review all the stats for OSA.

Statistics tell us that 75% of these tumors develop in the limbs (legs), and the front legs are twice as likely to develop this tumor.

Here’s another stat: the most common locations are “towards the knee and away from the elbow” or at the top of the shoulder, the wrist, and the knee.

Blackie’s metacarpal location is less common, but it is reported, as well.

Here are more numbers, or stats:

  • Median survival times for OSA cases with amputation and no other treatment is about four to five months. Dogs with amputation only almost all die within in one year; the statistic is 90-100%. Only 2% of dogs with only amputation are still alive at two years.
  • Median survival times for OSA cases with amputation and chemotherapy increase to ten to twelve months. If a dog gets both amputation and chemotherapy, 20-25% are still alive at two years.

Get a copy of this seminar to learn more on how Osteosarcoma is diagnosed, treatment options, amputation, and more!

Adding chemotherapy to Blackie’s treatment plan might help prolong his life. With amputation only, four to five months. Add chemo, and the stats say Blackie could live ten to twelve months and has a 20-25% chance of living two years. Was there a guarantee that he would be in the “good” half of the longer median survival time? No, but it was certainly possible.

I also told Blackie’s dad that chemotherapy is well tolerated, with 80% of dogs having no side effects at all. About 15-20% have side effects that are mild and self-limiting, meaning dogs recover with little intervention. This includes some nausea and/or diarrhea, which is treated at home with meds or antibiotics. The rest, 5% or less, experience severe side effects like the ones we expect in human cancer chemo treatments. Those dogs might have to be hospitalized as a result.

Blackie’s Treatments

So back to Blackie. He had three doses of chemo and experienced very few side effects at first.

But when he came in for his fourth treatment, he was not doing well. His legs were swollen and he was reluctant to walk. His right front leg was most swollen, and since he only has three legs, I was very concerned.

My training and my experience with OSA made me suspicious: had he had developed lung mets (metastasis)?

And did he have a very uncommon condition related to that called hypertrophic osteopathy (HO)? We see HO most commonly with metastatic disease to the lungs, especially OSA.

HO is when new bone develops along the shafts of long bones. But it doesn’t develop the way it should: it sort of juts out and builds out into the tissue. On X-rays, it looks jagged and spikey and painful. It causes a lot of pain and swelling because the bones are sort of poking out into other tissues.

Blackie’s chest X-rays confirmed metastasis (met). Plus, he had a skin met near his thigh and another deeper under his skin by his right humerus. It wasn’t good news, especially only three months after his amputation!

I took a few deep breaths before I went in the room to tell his dad that the statistics I gave him at the initial appointment had not predicted poor Blackie at all. He probably wasn’t going to be in the half of OSA dogs that live ten to twelve months with amputation and chemotherapy.

His tumor has turned out to be way more aggressive than the statistics led us to believe. This week, we are shifting gears to make him more comfortable and see if we can slow the progression of the mets.

Case: Daisy Mae’s Splenic Osteosarcoma

I saw another case this week where the stats were less than helpful, but the case itself is more hopeful. You can see Dasy Mae’s picture on my Dr. Sue Facebook page – she’s pretty darn cute!

Daisy Mae has OSA of her spleen, called extraskeletal OSA because it is outside the skeleton. It’s an uncommon tumor in the spleen; hemangiosarcoma and benign hemangiomas are more common. Since it’s less common, there is limited data in the literature.

Here are the stats from one report:

  • Median survival time for splenic OSA with only surgery was one month. That means half the dogs in the study with splenic OSA were alive one month later, and the other half had passed.
  • Median survival time for splenic OSA with surgery and chemotherapy was five months. That means half the dogs were alive five months later, and the other half had passed.

Now, I am certain I speak for all us dog lovers when I say that even the longer time frame, five months, doesn’t sound like a long time.

Even so, her parents decided to give Daisy Mae surgery and then conventional IV chemo followed by anti-angiogenic oral chemo.

When I saw her this week for a check-up 18 months AFTER her surgery, she was tumor-free!

So in Daisy Mae’s case, the stats were wrong, too. But in her case, they might have led us not to treat in the first place.

I always say I love when I am “wrong” because my patients outlive the stats.

Bottom Line: Use the Stats, Don’t Live By Them

So should you ignore statistics and published studies? Of course not! They can help you to make treatment decisions.

But you must realize that stats will never predict the individual. I personally hope your pet outlives the stats, but my advice — after all my training and years of clinical experience — is this:

Learn the facts, and then be hopeful.

Live longer, live well,

Dr Sue


Leave a Comment

  1. Isabella on August 18, 2013 at 5:59 am

    My question is about our 11-year-old basenji. We found a bloody mass in his mouth and it turned out to be squamous cell carcinoma. He went through radiation and the tumor nearly disappeared. However, on his next checkup about seven weeks after radiation, the oncologist determined that the cancer had spread to the lymph nodes in his groin area. She is recommending Palladia, but I’m worried about the horrible side effects and the fact that it doesn’t seem to show great results. Is there a holistic approach that would help our dog? Thank you.

  2. Ivan Dryer on August 13, 2013 at 1:45 pm

    My 16-YO Cocker has long been undergoing chemo for a large sarcoma that is now stable. He also has a nonmalignant adenoma tumor under his tail that grew quite large, then began to bleed and suddenly to shrink (due to Apocaps?). It started bigger than a golf ball and is now the size of my last finger joint–and still shrinking daily. His regular vet was concerned that it could fall away entirely and bleed profusely, requiring emergency surgery. His oncologist said yesterday that this was unlikely, but since it still has blood supply at the base, continuing necrosis could still open a vessel–again requiring emergency surgery, which I want to avoid because he also suffers from congestive heart failure, and anesthesia could be deadly (not to mention that I can’t afford it). I wonder if this presentation is something you’ve experienced and what the outcome might be; might it just stop shrinking (I recall Dr, Dressler mentioning a case wherein a tumor simply vanished with no ill effects)? Thank you!

  3. Lyndsay on August 4, 2013 at 10:31 am

    I appreciate the information that was emailed to me, sadly though i am currently unable to pay for any treatment to assist my lovely staffie, but thank God for the P.D.S.A. in the UK. They have told me after xraying her she has a mass on her chest but due to her bone structure cannot define exactly but suspect cancer and have put her on steroids,they cannot afford ct scans etc,so have to cope with just basic equipment.Im gleaning any info i can to help her.I had bowel cancer and the tumour was too big to operate,however i was lucky and was offered a trial,i also read how ginger could shrink tumours and ate it a lot.the doctors were surprised at how rapidly the tumour shrank,operated and treatment was successful so can i give my dog ginger in her food and if so what amount? I would be very grateful for any advice you could give me.

    Many Thanks
    Lyndsay Bourke

  4. Sue on July 31, 2013 at 3:51 am

    My 9 yo shepherd mix, Abbie was diagnosed with squamous cell carcinoma of the tongue in Nov 2011. In Dec, she had surgery which removed a large part of the left side of her tongue, with clean margins. She had a couple of chemo treatments (carboplatin) and the SCC came back. More surgery, another round of chemo with bleomycin and on the last treatment she was examined again and the tiny red spot on her tongue was the SCC again! At no time did she stop eating or act sick.
    The oncologist said there wasn’t much more they could offer, maybe freezing
    the spot.
    But no guarantees. In a month, we could be facing the same scenario. I decided to stop putting her through any more. That was in July 2012. She is still with me. She is still eating although it’s a messy process. The tumor is quite large, but she doesn’t seem to be in pain. She takes pain meds and half a Previcox daily.
    The doctor thought it would be a few months and it’s been a year.
    She is now 11.5yo and each day she’s with me is a gift.

  5. Renee Peters on July 30, 2013 at 9:44 am

    Our 8.5 year old black lab/beagle mix diagnosed with fibrosarcoma of right front leg, this month. Path report says grade 3, mitotic index 1-3, large areas of necrosis, inflammation, poorly differentiated tumor with dirty margins. Surgical report says 2.5x2inch mass occupying sub-q space. Our sweet girl is very emotional and prone to occasional bouts of depression. She has not fully returned to herself since surgery so we will not be undergoing the suggested radiation treatments as we feel it would be too much of an ordeal for her. Alternative vet says her food, Fromm grain-free, game bird is fine. But am changing to whole food diet. Supplements he recommends are from Standard Process: Canine Immune System Support for

    immune system regulation, Organically Bound Minerals to support parasympathetic nervous system and adrenal gland function, ThytrophinPMG for thyroid gland support/regulation, A-F Betafood detoxification for liver and gallbladder, decongests liver. Dr.Xie’s Jing Tang Herbal Inc. ” Max’s Formula” Chinese herb to slow tumor
    growth. Alternative vet conducted exam and sad her thyroid is 7 out of 10 and liver 3 out of 10 so he wants to raise these. Blood work in May, prior to diagnosis showed liver amylase at 395 which is low. If you can please review for us as we are hesitant about planning supplements on our own. Thank you sooooo much for writing The Dog Cancer Guide, it has helped us immensely.

  6. Natalie on July 5, 2013 at 6:42 am

    My dog Rocket got his exam and the vet said that he was one of the healthiest dogs she had seen at his age (10 yr. Terv). She gave him his rabies shot and we went home. Within weeks, he developed a swelling at the injection site which the vet could not diagnose and then 2 months later she said it was sarcoma. I lost Rocket 6 months after the rabies shot when he had been pronounced very healthy. Had I not gone to the vet he would be alive today.
    I think the veterinarian community should have a standard that you don’t give a dog over the age of 9 yrs. a rabies shot without doing a titer test first that may delay the giving of the shot and perhaps protect the dog. Also, no vet would help him because they said it was too big. In that case I think that the owner should be given data on a true Ketogenic Diet instead of just a passing suggestion that the diet should be better. (He had a homemade diet with rice)

  7. Dona on July 4, 2013 at 10:00 am

    my 13yr old cattle dog has a tumor in his bladder he is on proxican Iwould like to know how long he has?

    • Susan Harper on July 12, 2013 at 2:26 am

      Hi Dona, I’m sorry to hear your dog has a tumor. Please understand there is no way to give you any sort of prognosis through a blog. Your dog is not a statistic with a pre-determined expiration date. But let’s work with this…. here are points you need to find answers to: 1. What is the diagnosis 2. Has your vet given you his or her opinion about possible treatments and a prognosis? 3. How is your dog… feeling OK, eating?, pooping well? 4. What king of diet are you feeding? 5. What is your priority for your dog? The book ‘The Dog Cancer Survival Guide’ by Dr Dressler and Dr Ettinger is the best source of information to help you navigate this journey and as you get the answers to the questions I’ve posed, you’ll be able to really be a champion for your dog and make decisions that you feel confident making. You need to take care of yourself through this, not only so you will stay healthy and well, but so you can give your dog the best care possible. There is so much you can do, and please don’t focus on what statistics might give you as an ‘end date’ for your dog. Your dog is an individual, and the happier and more comfortable you can make his or her life, the better your dog can handle whatever comes. Please check out The Dog Cancer Bundle which is a great place to get the book. Take a deep breath. All the best, Susan from the Dog Cancer Support Team

  8. Scott on July 3, 2013 at 6:59 pm

    I hope this message find you well. I am sorry to interrupt you over the holiday. You have come highly recommended from several different sources. I apologize for the unorthodox manner in which I am contacting you.

    I have a 14 year old Golden Retriever named Biscuit.

    Starting almost 3 weeks ago Biscuit had a huge loss in appetite. It was difficult to get her to eat her regular food. This has happened before so we gave her chicken and rice and we figured we would give it a few days to see if it passed but it didn’t. Finally, last Monday we took her to her doctor. She lost about 7 lbs. They did a full blood profile, urinalysis, stool sample, and xrays of the chest and abdomen.

    The doctor said Biscuit was slightly anemic, her white blood cell count was slightly elevated, and her kidney count was slightly elevated. The xrays were inconclusive but the doctor saw a few things that were questionable and recommended we bring her in last Wednesday for an ultrasound of the abdomen. She put her on a 10 day round of antibiotics and pepcid.

    The ultrasound confirmed that she has 2 masses. One on her spleen and one on her liver. And that this is most likely what has been causing her distress. The doctor doesn’t recommend that we do anything invasive, mostly because the mass on her liver is inoperable. He said if it were just the spleen then it would be a consideration.

    Biscuit is 14 and I want to keep her comfortable and happy and as healthy as I possibly can. The doctor told us to continue with her daily routine and feed her what she is willing to eat. She seems to be doing better in the last few days. I am just afraid that things may change after she finishes the antibiotics.
    I brought Biscuit to an Oncologist who has recommended a CT to determine if it is worth it to do surgery.

    I spoke with another doctor who thinks that the mass on the liver is not as much of an issue as the mass on her spleen. He says that whether the mass on her spleen is malignant or benign it will eventually bleed out and he believes that the spleen should be removed. He said if its malignant and he removes the spleen that could give her an additional 3-6 months. If it is benign than this could save her life. I am very hesitant to operate because of Biscuit’s age and fragile state.

    What might you recommend for Biscuit?

    I’ve ordered Apocaps and Yunnan Baiyao. Might you be able to recommend what is best and proper dosages? Biscuit weighs approximately 65lbs.

    Any help or information you’d be willing to provide would be greatly appreciated

  9. kimberly on July 3, 2013 at 7:15 am

    What is mastesis?

    • Susan Harper on July 8, 2013 at 2:37 am

      Hi Kimberly, I think you mean ‘metastasis’ which basically means cancer spread. There are many, many variants to this and it can only be confirmed by a veterinarian performing xrays, blood tests urine tests, or other diagnostic tools. Spread is not good, but you need to have a confirmed diagnosis before getting too worried. I hope this helps. From Susan on the Dog Cancer Support Team

  10. KAREN LAWRENCE on July 3, 2013 at 2:41 am

    Thank you, for saying each case is individual !!!!!!!!!!!!!! WHEN I FIRST TOOK MY GREYHOUND TO AN ONCOLOGIST,( WILL NOT MENTION THE NAME), SHE SAID WITHOUT A BLINK,” HE IS TERMINAL, AND IF YOU SEE THAT HE IS IN PAIN, BRING HIM BACK, AND WE CAN DO AN AMPUTATION, AT ANY TIME!” She gve him a few months, did not really suggest anything else! I left that office angry and terribly upset!! (Sam had ostersarcoma in the lower wrist, of his right front leg)

    I took him to Blue Pearl, to another oncologist, which looked at him as an individual and treated him as such!! He has had an amputation, ( runs with his greyhound brothers), and 5 rounds of Carboplatin, ( donated by Ohio State University,greyhound trials), a protocol of Piroxicam, Furosemide, cyclophosphamide, k9 Immunity, Immunovet, Artemix and lots of love. (He is a happy boy.) It will be a year this August, since he was first dx.,clear and going strong !! I cherish each day I have, with my wonderful Friend!

    I use your book as a reference point and for anything that needs more defining!

    Karen and Sam

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