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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. Alexandra on August 6, 2023 at 7:57 am

    My 7.5 year old rescue Sophie had her spleen removed 3 weeks ago. The pathology report came back with a diagnosis of 1. Splenic Masses: Spindle Cell Sarcoma and 2. Spleen: Diffuse, white pulp marginal zone expansion. The oncologist said prognosis is “guarded” . He is recommending chemo – 5 sessions of Doxorubicin, and stated that “for this classification of splenic sarcomas no study has been published investigating whether adjuvant chemotherapy makes a significant difference to survival outcome when compared to surgery alone.” I have followed up with additional questions and his last response to me was “you are splitting hairs, the prognosis is the same no matter the origin, and most spindle cell tumors are treated the same way!” Perhaps I’m suffering from analysis paralysis but I just don’t feel I have enough information to make an informed decision on what avenue to take – chemo or no chemo. I have spent days searching the internet, YouTube and FB groups for information on this diagnosis and have not been successful. In fact, I’m more confused and “paralyzed”. I have ordered your book in hopes that it will help me navigate through this awful journey but in the meantime, can you help me understand this diagnosis or point me in the direction of where I might find some easy to understand information on this type of cancer so that I can decide what to do. Thank you in advance!

  2. Hsiu Hadley on February 6, 2020 at 11:02 pm

    This article is excellent! I’m typing up the info for my class. Thank you!

  3. Esther Flores on February 26, 2019 at 1:30 pm

    Hi Dr. Sue. my pet has cancer in her nose, she is a small 11yrs old Shih Tzu (Lee V) we opted out of radiation and or chemotherapy due to her age, the cancer was too advanced by the time she was dx’d, she was given 3 mos. she was dx’d in Oct of 2018, I have seen how each day she is showing all the symptoms her oncologist told us we would see. Her nose bleeds are occurring more frequent, yet she still has a lot of spunk in her, eats well all her blood work comes back normal, she is on prednisone and tramadol in other words ( comfort care) I no longer count the days or weeks she is with us, I thank God everyday for that day that she is with us. We’ve had many pets but Lee V stole my heart the first time I saw her, and when she is gone there will forever be a hole in my heart. Thank you for the Time article, I no longer count the hrs. or mins. because who knows no matter how bleak things may look I treasure all of the time I have had with her. Thank you so much .

  4. Tina on February 7, 2019 at 10:21 am

    My puppy, a Labrador, has been diagnosed with osa. She is 15 months old. We are devastated. Is there any chance of survival?

    • Dog Cancer Vet Team on February 8, 2019 at 7:43 am

      Hey Tina,

      Thanks for writing. As we’re not veterinarians here in customer support, we can’t offer you medical advice. However, we can provide you with information based off Dr. Dressler’s, and Dr. Sue’s writings 🙂

      Making a decision on which treatments to undergo can be one of the hardest things that you have to do as your dog’s guardian. You know your girl the best, and will be able to decide what treatment options YOU think would be best for her. Is she mentally, and physically, able to undergo surgery or chemotherapy? Are you willing to handle the side-effects? How important is life-quality to you? Those are just some of the things that you will have to take into consideration when making your decision, and for each dog guardian, the answer will be different because each dog, and their situation is unique.

      Here are some articles that you may find helpful in making a decision for your girl:

      You should get a copy of the Dog Cancer Survival Guide. Dr. Sue dedicates an entire chapter to Osteosarcoma where she writes about standard treatment of care, signs of osa, prognosis, and protocols, to name a few.

      As Dr. D writes in the Dog Cancer Survival Guide, there are many things that you can do to help your dog with cancer, such as conventional treatments (chemo, surgery, or radiation), diet, nutraceuticals, mind-body strategies and immune system boosters and anti-metastatics. Here’s a link to the Dog Cancer Diet PDF that readers of the blog can get for free :

      Once you know your options, and what is most important to both you and your dog, you will be able to make a decision based on what you think would be best for your girl. Consult with your vet, or oncologist, and don’t be afraid to ask questions– you are your dog’s guardian 🙂

      We hope this helps!

  5. Rebecca McConnell on July 31, 2018 at 3:50 am

    Our 8 1/2 Doberman had a tumor over his eye which had already spread before removal. He also has auto-immune disease and has been on thyroid meds for years. We decided to forego chemo and to concentrate on diet using Dr D’s recommendations, Apocaps, and K-9 Immunity plus and a few other supplements – in order to keep him happy and comfortable. We gradually weaned him off the Apocaps and he’s been off a year. So far it’s been 3 years since the surgery and he’s about 11 1/2 to 12 yrs old. He is still on the diet, K-9 Immunity Plus, thyroid meds and supplements.

    • DogCancerBlog on July 31, 2018 at 7:02 am

      Hello Rebecca, thanks for writing and for sharing your story with us! 🙂 It sounds like your boy has an amazing support group and we’re so happy that you were able to gain another 3 years with your beloved boy!

      Warm wishes to you and your boy from all of us here! 🙂

  6. Teresa Bishop on July 10, 2018 at 8:49 am

    I have an 11 year old female lab. Her name is Angel. She has bone cancer in her back right leg (between the foot and ankle, per say. She has bone spurs in her back, hip dysplasia and she has a questionable spot on her lung. She is on Tramadol and Galliprant 2 x a day for each drug. This has been going on for 3 months now. She is not using the back leg any longer. She still eats good, chases the cat and barks at the cows next door. She is grunting, when she lays down, a lot more than she use to. The leg has a large hard knot where the cancer was found. She is such a sweetheart. I hate to see her like this. She is being fed rice, sweet potatoes, fish and veggies. She loves it. What do I need to watch for to make sure she is not suffering. 🙁

    • DogCancerBlog on July 11, 2018 at 6:51 am

      Hello Teresa, thanks for writing and we’re so sorry to hear about your girl! 🙁 It sounds like she has an amazing guardian. There are a few really great articles that we would recommend for you take a look at as they cover life-quality and pain.
      Here are the links:

      Your veterinarian may have some suggestions on what you could do to help manage the pain. A holistic vet may also be able to help you if you are doing a more natural or holistic approach to your girl’s health care plan 🙂

      Also, Dr. D suggests staying away from high carb vegetables, like potatoes, as they can break down quickly into simple sugars in the body and may end up feeding the cancer. If you haven’t had a chance to check out his Dog Cancer Diet, the link is below. You may find it really beneficial in providing a nutritious diet that promotes healthy cells and discourages cancer growth 🙂

      We hope this helps Teresa!

      • Teresa Bishop on August 1, 2018 at 9:26 am

        Thank you so much for the information. She has more good days than bad, but I dread when the bad days over power the good. She looks at me and I could just cry because I know she has to hurt but her sweet face just wants me to pet her and at the same time her tail is just wagging……

    • JennaRose on July 26, 2018 at 2:17 pm

      My dog (Boerboel) has Osteosarcoma began beginning March. I was totally disgusted by what Tramadol did to her and tried it on myself. Within 10 – 20 minutes I was throwing up all over my kitchen. I have her on marijuana which she get before bed – She shares my bed. I just powder it in a coffee grinder and add almost a level .6 ml measuring spoon to her food. Have taken her off Previcox since having her wrist wrapped up in… See below: Previcox is poison! It will be my last resort. She still limps but with Previcox it blocks the pain signals and she runs on it and it causes a lesion and the bone swells. She’s limping without it but at least not walking or running on it to cause a further lesion. She’s happy, cheerful and still able to dream without it since I have her wrist wrapped in the compress it really seems to be helping her. I also find the castor oil also helps. I soak it into 3 layers of folded bandage and then wrap and
      gently seal it with plastic cling wrap which I then cut the foot part of an old sock off and then place it over the cling wrap. I’m giving her 100 g of freshly pureed aloe into which I blend an equal amount of honey to which I add a bit of artemisinin. I believe this has stopped it from spreading to her lungs (aloe). She gets curcumin in her food. No dog food. Gets Meat (mostly chicken breasts) and lots veggies. No carbs. Lots garlic and ginger with cayenne chili to move the blood to carry the cancer fighting bombs around her body, lots fresh lemon juice esp with her chicken and 10g baking soda twice daily. Testing pH of her urine with ph paper to make sure it remains at correct level. Into her water bowl I zest a small lemon then pour over a kettle of distilled purified boiled water (no tap water), stir, allow to cool then add a few drops hydrogen peroxide and some boron water – It tests alkaline using pH paper. See recipe below. She also get 500 mg vitamin C once daily. To make liquid Sodium Bicarb*

      250 ml sterile water
      5 mg (level teaspoon) Bicarbonate of Soda
      1 ml DMSO (Dimethyl Sulfoxide) — 99 % pharmaceutical grade

      Prepare 250ml of sterile water and add 5mg (a level tea spoon) of sodium Bicarb.
      pH should be between 8.5 and 9.
      Using a 5 ml syringe, measure 4 ml of the Sodium Bicarb solution into a small bottle and add 1ml of DMSO
      *Always add DMSO to water and NEVER add water to DMSO due to the release of heat..
      For all cancers you can just rub this on your chest and it will absorb through your skin and head straight to the tumour.
      Natural Remedies – Barbara O’Neill
      For Bone Spurs: You can use cold compress as the best signs diminishing remedy.
      5 g boracic acid powder (Not Borax) I use it for my depression it works!
      800 ml water
      Dissolve boron in body temperature water – No hotter
      Being in South Africa I am still waiting for her Bloodroot capsules and laetrile to arrive. I did have a friend bring some back from America and she has recently finished her 90 capsules. It did bring out a whole glove she had had in her colon / stomach for around 4 years which was the last time I saw the glove. She’s swallowed a lot of strange stuff in her years. If you try and get it away from her she just swallows it. All the small stuff like socks etc has to be hidden away to dry in spar room where she can’t get it.

      Wishing you good luck with your dog!

      • Teresa Bishop on August 1, 2018 at 9:28 am

        thank you for sharing all your knowledge. I just breaks my heart to see her limp around. She does let our neighbors cows know she does not like them….lol…..she seems happy…..I just hope she really is.

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