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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: April 13th, 2021

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. Susan Kazara Harper on February 22, 2015 at 4:42 pm

    Hi Michelle, I’m sorry this reply has taken so long. What is the situation with your dog now?

  2. Michelle on January 31, 2015 at 12:36 pm

    I have a German Shepard blue heeler mix who is 13. I have noticed a lump on his hind end and thought maybe matted hair at first… in the last week it has become bigger than a soft ball. It doesn’t hurt him when I touch it but he does not walk for very long. And he eats laying down. I’m afraid I’m gonna have to put him down but wanted to know if maybe it could be a cyst

  3. KRae on January 11, 2014 at 4:32 pm

    Max had weak hind end, collapse, wobbly episodes twice, about 10 days apart. That was several months ago. 2 1/2 weeks ago he had a mast cell tumor, which grew to about the size of a quarter in 10 days, removed from his thigh (grade 2). Today a very small lump on his head, which appeared over 5 days, was aspirated and determined to have a few mast cells which will be surgically removed and biopsied next Wednesday. So my question is: what is done to diagnose an internal cancer that may now be appearing as an external cancer?
    Thank you so much! (Max’s person)

  4. divya on April 18, 2012 at 11:59 pm

    my dog is suffering from cancer and her age 13 yrs.. doctor said operation is bit risky and she may also it-seems i’ am worried about that.. as she is too old for operation and she cant bear the pain also.. please suggest me any home medicine for her and she is not eating her food also…

  5. Yash on March 8, 2011 at 3:49 pm


    My GSD got very ill a week ago. He had diarrhea for 8 days, vomiting for 3 days and then all of a sudden started getting very weak. He didn’t even want to go outside for walks, which was so abnormal because he was usually the first one to the door. He got so weak that he didnt want to get up or eat anything. He didn’t even want to drink water. I took him to my vet and they did an xray and found he has an enlarged spleen. He was also dehydrated. We ended up leaving him for 2 days at the hospital so he could get IV fluids and be monitored. Today we had the ultrasound which showed an enlarged spleen and a possible mass. Besides having spondaylosis, he is otherwise healthy. His liver and kidneys look good and so does his blood work. I want to do what is best for him but I am scared of getting the surgery due to his age. Can you please give me some advise? Thanks


  6. Karen V on February 23, 2011 at 6:40 am

    Dr. D,
    My lab is 10 years old and I am wondering how you feel about using red clover,
    and Burdock?
    Please advise!
    Thank you,

    • DemianDressler on March 8, 2011 at 10:20 pm

      Dear Karen,
      burdock has some interesting anti cancer effects, although not as well supported as the “big guns” in the Guide (Apocaps, artemisinin and others). Red clover evidence is rather meager in my opinion.
      Dr D

  7. carissa on October 10, 2010 at 12:52 pm

    Hi, my dog a male, has a lump on his breastbone area. It has grown signifigantley in the last 5 months. Some people say its a fatty “growth”. I brought my female blue cattle when she was two years, and she had one lower down although her’s has not changed size or shape. His is often red and sore looking, although it does not hurt him if I press on it. Any ideas? Vets are soo expensive in this country, I need to know if I should saving for this. Thankyou.

    • DemianDressler on October 13, 2010 at 4:59 pm

      Dear Carissa,
      as you know, dog cancer is the number one cause of dog death. As you know, how a lump feels and looks does not tell you if it is dangerous. Please get it checked out, at the bare minimum with a fine needle aspirate. Your vet can give you prices. Please don’t wait. See if your vet (or others in your area) take Care Credit, which is a payment plan program that can help with finances.
      Dr D

  8. Susan on September 21, 2010 at 9:08 am

    My 12 year old Weimaraner had sudden onset hind weakness in February this year. Our vet felt an enlarged spleen and we whipped it out immediately. It was HUGE!, but my vet felt he got it all. Still, the diagnosis of a hemangiosarcoma freaked me out. We had lost our beloved 9 year old dog last October to cancer. As my 12 year old, Keymos, healed from surgery, we immediatley put him on the full dose of Apocaps (discovered during the previous experience). With a fully nutritious, natural diet, and good supplementation, plus a metronomic chemotherapy from our vet, Keymos has been healthy, happy and strong ever since. The prognosis is dire for hemangiosarcomas, sometimes only weeks. But we are seven months post-op and he is doing great! And we intend to keep doing so. Thank you Dr. D and Apocaps!

    • DemianDressler on September 29, 2010 at 8:47 pm

      Thank you for your kind words Susan.
      Best to you and to Keymos!

  9. franklin mattingly on September 21, 2010 at 9:07 am

    just a little over one year ago my white german shepard had a limp that started at 14 year 4 month of age the next thing was she collasped a couple times but came out of it I took her to my conventional vet it was hesocarsonma. she was given 3 weeks to live but I purchased the cancer book dr dressler wrote I also put her on high protien diet steak ect, followed the directions in the book I got here, bought the medical mushrooms and took her for accupuncture treatments she lived a good quality of life for about 23 weeks.thankyou dr vet said I could not and would not be able to help her but I was able to help her stay happy and it was worth the time and money I conventional vet is a very smart man but he did not understand why I was trying to keep her going.he may have resented that I went to a holostic vet but I felt it was my duty to help my old dog.she saved my life one time I would not be writing this now if the dog was not there to protect me that one night.thankyou dr dressler again for your book!I now have a 13 month old WGSD she is a wonerful pet and I am also considering the apocaps.If anyone out there has a dog with cancer it will do you good to read this book.

    • DemianDressler on September 29, 2010 at 8:48 pm

      Thank you Franklin, and I am so pleased to hear that your companion did so well!
      All my best,

  10. Ann Marie Reed on September 21, 2010 at 4:18 am

    Dear Dr Dressler,
    Thank you so much for this explanation, and also to the new information on the vaccine. Even though I lost my baby to this awful disease last October I want to know everything I can about it. any one who comes to the canine cancer list I always post and tell them they also need to find the sumner Foundation yahoo group as it is specific for HSA. your book which I loved is always recommended.
    As well I had both my regular vet and my alternate vet apply for your book.It is the same as sittingb across the table and picking a vets brain for five or six hours.God bless you there was and is such a need for your book.
    Ann Marie

    • DemianDressler on September 29, 2010 at 8:49 pm

      Thank you so much for you kind words Ann Marie. All my best,

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