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

My Dog is Acting Fine … And Got Diagnosed With Cancer?!?

Updated: June 14th, 2020


If your dog is acting fine, even though she has cancer, there could be a couple of reasons. Read this article to discover what they are.

How is it possible that our dog is acting fine — no signs of disease — and have cancer?

This is a pretty common question. It’s also a common scenario.  MANY dog lovers have gone to the vet to have a lump checked out, something that doesn’t seem to bother their dog. And then, sometimes even on the same day, the news arrives: cancer.

Whether this is a mast cell tumor, osteosarcoma, lymphosarcoma or some other kind of cancer, the news is horrific.  There is not much that can truly prepare someone for the shock.

Blam: your dog is acting fine … but has cancer.

In their shock, many clients and readers of The Dog Cancer Survival Guide ask: how did this happen?

My Dog Is Acting Fine. How On Earth Could He Be Sick?

It is very natural that this question arises.

If my veterinarian is saying that my dog has cancer, how did this happen?

Aren’t cancer patients sick?

Shouldn’t there be some other sign if it really is as bad as the vet is saying?

The answer is no, not necessarily.  The key, in part, is in looking back to the natural world.

It’s In Their Nature

Here’s why: in nature, it is not helpful for animals to act sick.

Sick animals get eaten because they stand out from the pack.  Sick animals attract the attention of predators.

Another reason acting sick in the wild is detrimental is that a dog could lose its pack position.  To maintain their status among peers, it is better to be healthy and vigorous.  Those acting sick lose status.  Thus they have a strong social penalty for acting ill.

It becomes clear that showing signs of sickness can make matters worse for a dog in the wild.  There is a strong instinctive drive hide illness.

Get a copy of the Dog Cancer Survival Guide to read more on canine cancer

What Works In Nature Doesn’t Work in Domesticity

This instinct creates a problem when our canine companions are in need of medical attention.  Driven by this strong natural tendency, dogs hide their physical problems from those responsible for them: us!  Many medical problems (not just cancer) are kept under wraps, masked from caring dog guardians.

… Or Maybe There Are No Symptoms Yet

There is another reason dogs can act as if nothing is wrong while there is a cancer brewing.  Maybe a dog has a malignant tumor, but it has not spread enough to cause really significant tissue injury.

You may know a human who found a lump, and it turned out to be cancer, even though they were otherwise healthy. They didn’t know the lump was malignant, because it didn’t cause pain.

Tissue injury is what causes pain, and some tumors just don’t cause enough injury as they brew and progress. Until they do, both humans and dogs with cancer can act normally.

Decompensation = Problems Become Clear

Cancer usually starts as just a few old, deranged cells piling up. They should have already been replaced by healthy, vital cells by a process called apoptosis.  But cancer suppresses apoptosis (it’s one of the hallmarks of all cancers). No apoptosis = cells live forever.

No apoptosis = cells live forever.

If there is an apoptosis deficiency in the body, these cells will accumulate.

Meanwhile, the normal healthy cells continue to support your dog’s body, and your dog is acting fine.

This continues until those healthy cells can’t keep up.

Once the effect of the pile of deranged cells tips the scale, we see the problem.

This tipping point is called decompensation, a fundamental phenomenon in health and disease.

There is an in-depth discussion of cancer development in several chapters in my book. You may also be interested in reading chapter 3, for free, here.

Best to all,

Dr D


Leave a Comment

  1. Russel May on July 7, 2020 at 10:07 am

    My 10 year old Male labradoodle has a tumour in his anal gland which my vet thinks has spread to his lymph nodes. I’m not putting him through surgery what can I do

  2. Tony Alexander on June 17, 2020 at 3:42 am

    My dog was diagnosed w a cancer tumor in Jan 2020 they said without surgery or chemo it was bleak. Even after a test w a needle into the tumor they weren’t sure what type without surgery. I decided no chemo or surgery. I immediately put him on a holistic diet of cooked chicken veg, flaxseed oil, liquid good immune supplenent, medicinal mushrooms and krill oil. It’s June 2020 and he seems fine. Acts like a puppy he is 13 and a schnauzer. My question is what else can I do I’m thinking about adding Apocaps. Thankyou for your Great Book u wrote.

    • Molly Jacobson on June 18, 2020 at 10:40 am

      Hi Tony! Wow, that’s all wonderful news — good job! It sounds like you’ve got a great system there, and Apocaps wouldn’t interfere with anything on the list. I would definitely consider it.

  3. Cathy Lou Sverev on June 16, 2020 at 5:56 pm

    Our family and our beloved SandyLou have been such fans of Dr. Dressler. Your clinical information combined with compassion and empathy make your book so valuable. This has been the most difficult road for our baby, a shepherd mix, who was just preparing for her test as a therapy dog when diagnosed. We fought her lymphoma and she bravely gave us an additional year. Sadly, she was out to rest on May 17th. We want to sincerely thank you for all you do for all of us as we travel that road with our pets. Keep up your important work and be safe. Boris, Cathy, Lace and SandyLou

    • Molly Jacobson on June 18, 2020 at 10:41 am

      Thank you so much for this message, Cathy. We’re so sorry to hear about SandyLou’s passing, and are so happy that you found Dr. D’s book so valuable. Please accept our heartfelt condolences, and thank you for taking the time to post this in your grief. Dog lovers are just the best breed of people 🙂

  4. Edward Halverson on November 12, 2019 at 5:12 pm

    My wife and I are on verge of a divorce.

    She won’t let go. We have been bandaging her for over three months.
    Dog still acts fine, but the dressing thing is driving me crazy.

    Oh yeah, she is a nurse.


  5. Jean on July 23, 2019 at 4:23 am

    I am in an interesting (heartbreaking) bind. I started my 13-year-old dog on the dog cancer diet shortly after an inoperable mast cell tumor was found in her mouth. She LOVED it. We also went for palliative radiation and palladia plus prednisone. The radiation basically eliminated the tumor in 3 treatments. However, the Palladia and prednisone were supposed to mop up/supress regrowth and new growth. The day before her last (4th) scheduled radiation, my husband woke up to find her vomiting, shaking, pooping in the house, and obviously in pain. I had gone away the night before for work, and I also had started her on quite a bit of fish oil two days before. She was diagnosed with severe pancreatitis, which has taken her several weeks to recover from. I don’t know if the pancreatitis was brought on by the stress of me going away, the fish oil–maybe I should have added it more slowly–or the prednisone, which can be a suspect, or the Palladia. Regardless, we are now in a situation where she had to be taken of fall the anti-cancer meds and she couldn’t have her last radiation treatment. She is on Hill’s I.D gastrointestinal low-fat food because of the pancreatitis. Her liver enzymes are high. She was in a lot of pain because of teh pancreatitis. I am now not able to put her back on the dog cancer diet because of fear of another pancreatitis attack; they discontinued the Palladia and prednisone (honestly, the prednisone really changed her personality and I’m glad we’re done with that); because of her liver enzymes, our painkiller options are limited . . . I guess my intention is to tell everyone to go a littel slower when introducing new food, especially high-fat food, just in case, and keep your baby’s stress levels low. Get lots of support from vets with alternative perspectives, but be cautious about introducing new things to their diet. Personally, though, I wish I had said no to the prednisone. I think that may hav been the cause of all of her problems. Now we are faced with the choice of hospice care or choosing a new chemo drug. It is heart-breaking. Meanwhile, she continues to recover slowly and is still able to play keep away, enjoy eating (even though she misses the home-cooked tilapia and brussels sprouts), and letting us cuddle with her, something the prednisone-induced personality changes had taken away.

  6. Elyse on January 30, 2018 at 11:46 am

    My 16yr old german shephard chow mix has hemangioma his liver spleen and heart are all enlarged. He has had an increase in his appetite as well. He eats like crazy but cant get full. He is also losing a lot of weight. He is skin and bones. All he has is a bloated tummy from the tumors. At 81lbs he looks emaciated. We have been giving him 2 extra meals on top of the 2 he has already but the poor thing is still always hungry. The vets always say if they are eating and drinking they are ok but I dont know. I think he is suffering. He is still able to get up but its a little difficult for him and he isnt incontinent either. He is lazy but stillbshows an interest in people car rides and walks but he cant go for long walks or his hips give out. I wander if we should put him down so he want suffer but how can we put a dog down that still wants to eat drink and go for walks. I wander if he is just hiding how much pain he is in. The vets daid he is s unique case because all the other animals with cancer that has spread to several organs dont eat or drink anymore and haft to be put down.

  7. Jay Jay on August 22, 2010 at 4:05 am

    My Siberian Husky is almost 10.. and last summer I shaved him to find several large masses. After talking with my vet, it was determined he has cancer.. SInce then I have kept an eye on the masses and watch for new ones. He does have a few new ones.. I refused to have a biopsy done to prevent the spread of the cancer cells. I will not allow him to be put through any treatsments as he seems to feel ok. My question is , Does cancer make him hungry all the time.” HE acts like he is starving. He has normal bladder, and bowel functions. But he wants to eat, all the time. Any one have any insight for me??? I appreciate any help with this. Thanks

  8. Nancy on January 6, 2010 at 11:39 am

    Snoopy, 7YO neutered beagle, had bloody urine last summer. vet put him on primor (antibiotic) and UTI cleared right up (confirmed by culture / urinalysis) only to reoccur in 1-2 weeks. After the third time, vet said if it reoccurred we should x-tray (thinking bladder stones) When bloody urine reoccurred, x-rays showed enlarged prostate and rectal palpation caused a bloody goopy discharge. Vet thought prostate abcess so put him on 30 days antibiotic and to recheck and ultrasound a week after antibiotics were finished. A few days after stopping the antibiotic, Snoopy had difficulty urinating so he went back on primor and because the ultrasound dr. could not schedule ultrasound, vet sent him to another clinic where they could ultrasound sooner and do surgery (for abcess) the next day. Unfortunately ultrasound did not show abcess but showed a mass so they did a biopsy (ultrasound guided) which ended up being carcinoma.

    Other than the few days off the antibiotic, Snoopy has never acted sick. Not sure if to count the diagnosis as last summer when urinary symptoms started or last month – december 9, 2009 – when he had his ultrasound. Either way, so far he has not acted sick and plays / runs very hard at the dog park.

    Since his diagnosis, he is now on piroxicam (and misoprostol for the piroxicam side affects) as well as the primor. I also put him on mushrooms, noni juice, turmeric (the 95% cucurmin) caprylic acid, saw palmetto, cleavers, echinacea – add all the herbs / supplements to his food and he eats it right up. I also switched him to a low carbohydrate food.

    So now he is 1 month after his diagnosis (seven months since symptoms started) and so far he is feeling / acting great and eating better than ever (he loves his new food as well as the supplements) I know this can be a deception – many years ago I lost a horse to lymphoma who never acted sick until two days before her diagnosis / euthanasia and when they did a necropsy, they said she should have been dead a year. I also lost a dog to osteosarcoma who had her leg amputated and did the chemotherapy – only to have her jump off the bed and break another leg and x-rays showed cancer in that leg as well as her spine (she was then euthanized) She never acted sick and if she had not broken the other leg, she would have gone out and played that day just like always.

  9. Hope on October 2, 2009 at 5:25 am

    My black lab was diagnosed with hemangiosarcoma in May 09. God willing, he is doing amzingly well. We opted against chemo as the odds are not good for this type of cancer and started taking him to an Holistic vet in June. In May 09, upon being ddiagnosed, our regular vet said that he would have 3-6 months without chemo. We are now at the 5 month mark, and for all appearances, there are no visible signs of cancer or symptoms. I urge you to take your dog to an Holistic vet, get him started on supplements, remedies and a raw food or homecooked diet – with no starches or grains, only protein and vegetables.

  10. james carrell on August 18, 2009 at 10:51 am

    for info on the TRANSFACTORS and a whole lot of other info, check out SHIRLEY’S WELLNESS CAFE

    good luck to everyone

Scroll To Top