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

The Sign of Cancer Hidden in Plain Sight

Updated: October 9th, 2018

We’ve been looking at signs of cancer.  So today, let’s look at a really obvious one that can fool all of us.

One of the first things I review during a patient intake is the body weight.  Next, I compare this weight with the numbers over the last couple of years.

So am I just interested in seeing if Fluffy has gotten chubby?

No, although body weight (in particular excess body fat) does have cancer links, especially with  mammary and bladder cancer in dogs.  Today we are interested in weight loss.

The reason why this is tricky is that weight loss is expected once we have a cancer diagnosis.  After the fact. We look back at the slowly dropping weight, and it makes sense now that we have our answer.

But what about before that?

Gradual weight loss can be quite difficult to catch.  We see our dogs every day, and often we simply cannot detect the slow change.   Here’s where you can rely on your vet to help.  Almost all of us vets will weigh our patients with every visit, and keep a record of it.

And this can be used to track changes.

Weight loss is common in cancers, especially if they have been growing internally for a while.

Why do dogs often lose weight with cancer?  Easy question, complex answer. First, they use a lot of calories.  Cancers are very busy, very active.  Abnormally so.  They divide and invade faster than most body cells.  And it takes a lot of energy making all these new cells.

Secondly, cancers are capable of literally hijacking the body’s natural fuel sources. The interfere with the ability of other tissues in the body to obtain energy. The quite literally rob normal tissues of fuel sources.

Third, at least later, they can cause drop in appetite.  When this happens, there is less fuel for the whole body.

When weight loss is severe, we call it cachexia.  There is abundant good research on this subject.

Many vets suggest examinations more than once a year, especially if a dog is elderly.  One of the things that can be caught at these more frequent visits is weight loss.

Now, to make sure there is no confusion, weight loss is not a sign of cancer only.  Many other problems, like diabetes, liver and kidney disease, pancreas issues, and other problems can all cause weight loss as well.

You can also weigh your dog at home.  It is best to keep a log of these weights written, so you are able to keep track of the trends.

Don’t forget to keep diet and exercise in mind.  If you change your canine companion’s food to a lower calorie diet, this can promote weight loss.  Similarly, increased exercise can cause weight loss as well.

But, if you see a gradual drop in weight and you have no real explanation for it, please get your dog checked thoroughly with your vet.

A good rule of thumb would be a weigh-in every 3 months.

For more information on signs of dog cancer, specific cancer types, and Full Spectrum cancer treatment, check out The Dog Cancer Survival Guide.


Dr D

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  1. Thembi on June 22, 2022 at 11:48 am

    Hi my name is Thembi my 3months puppy has stopped eating for 1 day and i took him to the vet he was diagnosed with parvo virus then he was put on a drip. The following day they said he was very energetic then later that night he didnt eat again and he was put back on a drip again on the third day they say he died i find it hard to believe it because he was not that sick when i took him to the Dr what even worse is that they didnt show us the body im so depressed right so i just want to know is it possible for a puppy to die so soon with a. Early treatment??

    • Molly Jacobson on June 24, 2022 at 3:40 pm

      Hi Thembi, I’m so sorry to hear about your puppy. What a terrible loss for you. Unfortunately, parvovirus is very aggressive and yes, can absolutely kill a dog in a very short period of time. It is also extremely contagious, so they have to protect other dogs in the clinic from it … which means they sometimes cannot keep the body for us. It’s one of the worst things that can happen to a dog, which is why vets like to vaccinate for it. I’m so sorry you lost your dog to parvo. <3

  2. Betty on December 20, 2013 at 3:55 pm

    I have a9yr old brindle amstaff and she is spayed, she has been chewing on the base of her tail lately. A couple of days ago I found a lump there and it seems to make her look at you weird when u touch her tail. she even tried to bite me and I have had her since she was 4m old and never has she bite me. It concerns me but I don’t have a vet as we just moved and her old vet is 140miles away, should I just keep a watch on her or get her in to a new vet?

    • Susan Kazara Harper on December 22, 2013 at 5:59 pm

      Hi Betty, A lump could be anything from a cyst, an abscess, or yes, something worse. If she’s really guarding it and moved to bite when you checked it out it sounds like it may really be bothering her, but dogs can be funny about their tails, even when we’ve known them all their lives. You won’t really know what it is until you get a vet to check it. I know you’ve recently moved, but you’ll need a vet for her at some point anyway, so I recommend you call around or get recommendations from your new neighbors and get her registered. With any lump or bump the vet will have a good feel, and perhaps want to do a fine needle aspirate, or a full biopsy. But you will need some type of exam to determine what it is. Hopefully it’s just a local annoyance that will be easily taken care of. Good luck!

  3. nancy on October 2, 2010 at 9:29 am

    My golden is 12 years old and had a tumor removed in her gum last year. It was cancerous and has grown slowly until a few months ago. It is now the size of a plum and is located between near her back teeth on the outside between the gum and lip. When she eats, it bleeds and causes upset stomach issues. I took her back to the vet but they said they will not remove it because it will just make the cancer more aggressive. I think they should remove a portion of the tumor and allow her to function and eat normally for as long as possible. I realize the tumor will grow back eventually. The tumor is in her palate as well but I want the portion hanging out of the side of her mouth removed. Am I wrong to think this can be done or should I get a second opinion?

    • DemianDressler on October 13, 2010 at 5:35 pm

      Dear Nancy
      I am so sorry to hear this news. Trust your instinct. One of the first steps in the Guide is getting a second opinion!!

  4. Gary Browning on September 23, 2010 at 6:48 pm

    My Rotty is almost 10yrs Old and has a lump on her back just Forward of her Hip and I’ve kept Watch on it Over the last year . At this Point It doesn’t seem to be Getting any Larger and I Just Keep Check on It .Recently I’ve Noticed a Lump on her Neck about the Size of a Tick Egg and After Watching and Looking at it Constantly it’s ( Smaller then a Marble and Soft ) hasn’t Gotten any Larger in Over 6 months She did Start having Problems getting up and I Cutt her Food Back a Lil as She Weighed approx 130 lbs and I placed her on Glucosomine ( 2,000 ) mg per day and For Over 6 Months she has Gotten better in Her Getting Up Although her Sister ( Another Rotty ) 8 yrs. Old keeps her Active . I have her on the Glucosomine as Well . I Think she is Part Goat as she Eats Constantly . But Like My Rotty in the Past I Realize when you get Old you are Not as Functional like Myself as I’m Disabled and I Love My Dog’s Dearly as They have been Very Loyal and Great Companions with Both having Good Temperment’s Around Family and Children . Thank You so Much for Your Articles as They are a Great Help ! May the Lord Bless You for Your Dedication !

    • DemianDressler on September 29, 2010 at 8:26 pm

      Dear Gary,
      I always advise getting it checked, as you may have guessed! All my best and thanks for the kind words,

  5. Jacki Wilson on September 23, 2010 at 10:57 am

    Dr. Dressler, My 12 1/2 year old Corgi was diagnosed with hemangiosarcoma on September 3. Since then I have bought and read your book and have started her on the diet you recommend along with Apocaps, K-9 immunity, K-9 transfer and most of the other things you recommend ie krill oil, mushrooms, calcium, etc. My vet, who is traditional as well as holistic also has her on 2 Chinese herbs, Wei Qui Booster and Yunnan Baiyao supplements. No chemo or radiation. My question is about the carbs in the diet. Would protein only be a better option and if I decide to do that how much would I substitute for the 1 lb. brown rice. Thanks for your help for Maggie and all the others you help! Jacki Wilson

    • DemianDressler on September 29, 2010 at 8:28 pm

      Dear Jacki,
      I do not advocate total carb elimination, rather carbohydrate restriction for dogs with cancer. On top of this, brown rice has some evidence for cancer fighting effects in people. Another option is steel-cut oats..You can read more about this by downloading the new dog cancer diet pdf which you can get at no cost. Access it on to the right of the title banner on this website.

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