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

A Sign of Dog Cancer to Know About

Updated: May 15th, 2024

What are the signs of dog cancer?

That’s a tough question.  There are internal cancers and there are external cancers.

With the external cancers, those that are found in the skin, the space under the skin, superficial muscles, or in bony structures that are close to the outside of the body, many times we see a lump.

(Find a lump on your dog? Get it checked ASAP!)

Sometimes external cancers can show up as an ulcer that does not heal. Other times it can look more like an infection, but the antibiotics just don’t clear the problem up.

But what about the internal cancers?

This is where things get rough.  It is hard to look at a loved dog and say whether there is an internal cancer.  We have many organs that can be affected. As a matter of fact, pretty much every organ in the body can be afflicted by this number one health problem of dogs.

With this fact in mind,  it might be worth while using some computer monitor space on a couple of blog posts, and look at signs of internal organ disease.  This way you can develop a framework that may be able to help you identify important changes in your dog.

In The Dog Cancer Survival Guide, we look at the signs of each of the common types of cancer. Here, we’ll go in reverse, where we look at what we might see in a canine family member and see if we can pinpoint the diseased organ.

Let’s start with an oddball, but one that we do see from time to time, and one that is easily mistaken for other medical issues.

Here’s how it looks in a dog:

Most commonly this will be a big dog, over about 45 lbs give or take.  German Shepherd, Golden Retriever, Schnauzer..something like that.

You might notice that your dog gets a little weak in the hind end.  This shows up like a bit of wobbliness, or staggering perhaps.  And it kicks in suddenly, no gradual onset.

This weakness can also show up as a sudden difficulty getting up after laying down. Or maybe sudden collapsing on the rear.

If someone were to check the gum color, it might be noticed that the gums looked very pale during this weak episode.  Next, after a short while, maybe a day or so, suddenly it goes away.

Look at the gums then, and they are pink once again.

Most of the time this is chalked up as a little stiffness, some orthopedic issue or other.  And most times, this would likely be a correct assumption.

But then the problem happens again.  Weakness, sudden onset. Wobbly back end or even collapsing.

What is going on here?

Well, this is one of the classic presentations of a bleeding tumor in the spleen, most commonly hemangiosarcoma.  This is a very aggressive, malignant tumor. There is a new treatment vaccine that may show some promise on the conventional front in development at Colorado State.

(I have seen encouraging life quality improvements and outcomes with  The Full Spectrum Plan and Apocaps in some of these patients.)

But how does this work?  How do these tumors in the spleen make a dog behave this way?

Well, the short story is that they bleed. These cancers grow out of the wall of blood vessels, and so often they are filled with blood. Incidentally, these cancers can show up under the skin as a soft or squishy feeling mass, which is sometimes mistaken for a benign fatty tumor. They feel soft because the blood within the swelling is squishy.

This is a good reason to get soft lumps checked.

Anyway, when the tumor bleeds, there is internal blood loss within the abdomen.  At this time, the dog gets weak and wobbly. The gums look very pale.  Now you can see how it makes a lot of sense.

The amazing thing is that the body is able to take the pooling blood and draw it back into the circulation.  This is called autotranfusion here.

When autotransfusion occurs, these dogs get strong again.  The hole in the tumor temporarily seals.  The gums get pink again. And the problem seems to just take care of itself.

At least, until the next time.

If you have a dog getting wobbly in the rear end, please bring your dog to the vet.  Yes, it could be the hips, or the back, but it could also be a whole slew of other things.  And one of these is a bleeding tumor in the spleen.


Dr D

Leave a Comment

  1. Nicole on April 11, 2021 at 2:06 am

    Hello I have a 7 year old staff x she we were told 18 months ago she had cancer, we have had 3 lumps removed from her but have decided it’s not fair to put her through anymore surgery, she has now started showing signs of loosing strength in her back legs & is on ongopain releaf, I definitely don’t want to see her suffer or be in pain but any help would be appreciated, she’s my best friend not ready to let her go

  2. Debbie D on February 23, 2020 at 7:23 pm

    Actually if you use the Chinese herb Yunnan Baiyou along with your recommendation, the odds increase two fold. Hundreds of reviews and comments of helping their dogs.

  3. Kelly Jo Ferry on January 14, 2019 at 3:07 pm

    I have a male 12yr old wolf hybred. Got him at a very young age, and he has always been our happy little clown. As a pup, he had health problems that were treated promptly (a pinky tip size hernia from his navel, and a prolapsed rectum). Other than this, he has been very healthy. About 4yrs ago, we noticed he was getting some lumps on his body. These are located near his back shoulder blade area, on the side of his lower abdomen, the neck area and, a growth has been growing out from under his upper eyelid. None of these things seemed to bother him and, he (up until very recently) continued to play, jump and prance like his puppy days. About a month ago, he was a little wobbly with his walking, but we assumed it was because he had just been diagnosed with an ear infection, which we treated as directed by the vet. At this time Micah also had a hematoma on his earflap, which healed into a cauliflower ear. After treating him with his meds, he seemed okay but not 100%.Currently he has been deteriorating very suddenly. Both eyes have a thick mucous and, he has lost complete use of his hind quarters. He cannot stand or walk on his own. I am heart broken and, I just dont know what to do. I work full time, but since the fires in our town, we are just living day to day in a motorhome. The house was lost in the firestorms. Any ideas or suggestions are welcome. I am desperate to find out how I can help my boy in any way I can. I love him so much. Thank you. Kelly Jo Ferry.

    • Dog Cancer Vet Team on January 15, 2019 at 8:45 am

      Helly Kelly,

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

      As Dr. Sue writes in the article below, if a lump is 1cm or larger, or has been there for over a month, get it checked by a vet ASAP. This might mean getting a fine needle aspirate (or a biopsy in some cases) to determine what the lump is– it’s better to know sooner rather than later. Here’s the link to the article where Dr. Sue goes into more detail on this:

      Deciding on a treatment plan for your dog can be difficult. Consult with your vet, or oncologist, and find out what options they recommend, as they know you, and your dog the best. From there, you will be able to decide what treatment options YOU think would be best for your boy. Do you think he can handle chemo, surgery, or radiation? 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.

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

    • How to make decisions about Dog Cancer Treatments
    • Why your personality is so important to your dog with Cancer
    • 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 :

      There are many things that make a dog’s life great, from their perspective, and Dr. Dressler created a Joys of Life scale to help readers determine their dog’s quality of life. You can find out more on life quality in the articles below :

      If you’d like to try some mind-body strategies, Molly wrote an amazing article on Magical Thinking and Dog Cancer that you may find helpful! 🙂

      Consult with your vet. They will be able to perform a fine needle aspirate, and recommend a treatment plan for your dog. They will also be able to provide you with some suggestions on your dog’s other signs and symptoms 🙂

      We hope this helps!

  • Eleanor gallacher on November 16, 2018 at 8:32 am

    My dog has lost weight also his face is getting thin .. he has diareaha about twice a day . He’s not lost his appetite. His bag legs a very week he finds it hard to put weight on his bag legs to poo. He’d been on steroids for11 year because if an allegy. He’d going deaf but I font know when to put him to sleep could you advice me please.

  • Kimberly on October 1, 2018 at 4:45 pm

    Evening, I have a female 6 yrs bluehealer, Gracie, i have just found a soft to touch knot on her lower breast area. She is coming in and I heave not had her spade but plan to cause she is just not having none of that, so. I’m afraid of what it could be. She active eating well like I said I just have found it could it be related with her coming in heat?
    Thank you for help

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