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

Does my dog have cancer? What NOT to rely on!

Updated: December 11th, 2018


Glad to see so many readers these days! Thanks everyone.

I have noticed that there are some misconceptions about dog cancer floating around that perhaps could be clarified a little bit. Specifically, there are things that people are looking at to deduce that their dog’s lump is NOT cancer…but the problem is that some of the reasons (to support a theory that their dog’s growth is “fine”) are not valid.

Here are some classics in the area of:

What Not To Rely On With Certainty

1. Your dog’s behavior.  Dogs can have pretty serious health problems and still walk around, eat, be in no apparent pain, etc.  Malignant tumors may not show any overall body signs whatsoever.  Anyone heard the phrase….”the doctor found a lump in my breast?”  Let’s think about this for a minute.  The doctor found a lump.  The woman was totally unaware there was a lump!!  This tells us that you can have a life- threatening cancer going on that is utterly without any overall signs.

2. How the lump feels and looks on a physical examination at the vet’s.  Okay, all of us vets have been guilty of feeling a mass and proclaiming the diagnosis (Fatty Tumor! Cyst! Adenoma! or whatever).  Folks, the reality is this: a very high percentage of masses with that feel and appearance actually are what they feel like and look like.  But, not all of them!  If I see 20 dogs with a soft mass under the skin that feels like a fatty tumor, I would not be surprised if one or two were not. I have encountered growths that for all the world feel like fatty tumors (lipomas) and turned out to be mast cell tumors or hemangiopericytomas (nerve sheath tumors), or even sometimes hematomas (blood pockets from some kind of impact or trauma).

Both of these (exam findings and your dog’s behavior) are unreliable.  Yes, sometimes we can get a high probability of a diagnosis and everyone is comfortable playing the odds.  But consider this:  how many of us wear our seat belts and how many of us wreck our cars?

Take home message: make sure you are aware that if you opt against a fine needle aspirate (see the last blog) or a biopsy (see the entry about Bjorn), you are playing an odds game that is not 100% versus 0%.  Some of the dogs with masses that look like they are benign growths and will fool everyone.  They come back to bite us later.

Best to everyone,

Dr Dressler


Leave a Comment

  1. Susan Kazara Harper on June 23, 2015 at 7:56 pm

    Ronda, Can you find another vet to consult? It doesn’t sound like you have a vet who is listening to you. The first lump could possibly have been a cyst that burst, but multiple lumps like that could be a variety of things. May even be a topical reaction to something. A vet should at least be able to do an easy biopsy on one. No one responsible would try to diagnos onilne. You need a vet who will work with you toward the health of your dog. Good luck!

  2. Ronda on June 8, 2015 at 8:08 am

    My dog has lumps all over his body he had one on his chest when I first noticed it it was very small within a couple days it was about 2 inches round I took him to the vet and she said they don’t operate for cosmetic reasons so before I could get another opinion the lump got as big as a baseball and burst.Next thing I knew he was getting lumps all over about 2 inches in diameter on the top of his skin .The vet doesn’t want to do anything I believe he has cancer and she will not tell me.

  3. Susan Kazara Harper on December 30, 2014 at 9:05 pm

    Hi Gemma,
    It could be anything from a local infection to yes, cancer, but before you get worried and scared, go to the vet. Even if it’s a bad diagnosis, your dog may not be acting any differently. When they get to the point that they seem to be in pain, it can mean it’s quite advanced, so you really want to catch this soon. Stay positive, make the appointment, and get it taken care of. You will feel much better. If you leave it alone the odds are that it will not improve, and may get much worse. Take courage and get it checked. Good luck!!!

  4. Susan Kazara Harper on December 29, 2014 at 6:38 pm

    Judy, If this 11 year old dog has only recently started showing allergy symptoms, it may be an environmental irritant. Especially as her paws and snout are affected… the areas that are in contact with the ground. What has changed? Carpet? Under floor heating? New furniture, new cleaning products, new laundry products? Chemicals are EVERYWHERE, and often our pets, who are in contact without shoes and clothes like us, can suffer a reaction. Really think of every detail, even outside. Any changes there? Take a breath and decide when the smptoms started, then think of every possible thing that may have changed in her environment. Take that list and pick one thing at a time to eliminate, or to keep her completely away from. Bathe her irritaed areas in warm water with diluted vinegar to clean any residue. I’ll bet you can detect the problem, then you can help her. If you leave it the odds are that she’ll get worse with the itching, and it may even spread to her mouth and nose as she’s trying to soothe herself. Good luck!

  5. gemma on December 25, 2014 at 8:53 am

    My mum dog has had a small spot on his neckline he was checked over and they said just keep a close look at it, he had it for a about a year, now over last week it got bigger and has burst with weeping blood but he dont seem to be in pain but looks sore and its swollen around it what coukd it be ?? X

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