Signs of Cancer

Cancer happens when normal cells don leather jackets and go on a vandalism spree

March 9, 2015 (published)
A bichon-westie named Fred was successfully treated for anal sac cancer. Photo by The John Urban Production Company

Most of veterinary school is the sort of info-packed blur of a distant past that probably belonged to someone else. (Hey, it was 25 years ago!) But a few key moments and phrases jump out of that rapidly spinning highlight reel. One is a professor saying, “Cancer does whatever it wants.”

In its most general sense, cancer – officially known as neoplasia – happens when perfectly quiet, normal cells don leather jackets and go on a vandalism spree. Basically cancer cells occur as the result of DNA mutation that removes the normal checks and balances on cell metabolism. These cells then go berserk, reproducing and growing faster and without the normal constraints of other cells. They take up space, eat all the food, and beat up their neighbors.

Cancer can affect any tissue in the body, so the options for signs (symptoms) are pretty extensive. That means any list of "Signs to Look For" will be both incomplete and not apply in every case. But, disclaimers aside, here’s my best shot.

  • Lumps, bumps, funny scabby bits, non-healing wounds. Generally things that don’t belong on the skin and are refusing to go away on their own need attention. This is doubly true if they’re growing, spreading, funny colors, or weird shapes. Your vet may recommend a biopsy or needle aspirate. Say yes.

  • Mystery limp. In general if your pet has a sore leg, the kind thing to do is to get it checked out. But, cancer can affect both muscle and bone and definitely gets higher on the list if there is no known cause of injury and especially for certain breeds. Your vet may recommend X-rays. Say yes.

  • Weight loss. Lots of things can cause an animal to lose weight, and cancer is one of those. If your pet has lost weight (and you haven’t put him on a crash diet or bought him a treadmill), it’s time for a vet visit. Your vet may recommend blood tests, X-rays, or an ultrasound. Say yes.

  • Change in activity. Like weight loss, a sudden drop in energy isn’t specific for any particular disease. However, unless you and your dog just ran a marathon, or your cat can’t get off the laser pointer train, it’s not normal for animals to have a sudden case of the blahs. Your vet may recommend….You get the drill.

  • Unexplained vomiting, diarrhea, difficulty breathing. Again, these are all signs that point to the veterinarian’s office under any circumstances.

  • Random bleeding – nosebleeds, skin bruising, blood in stool or vomit. Clotting problems can also be genetic or the result of poisoning.

You may have noticed that I said to say yes to the diagnostic recommendations in this list. Because cancer can do whatever it wants, the longer it runs amok, the more it’s like a teenager without any boundaries. The earlier it’s diagnosed, the better the chances of successful treatment or at least the sooner you’ll know the likely outcome.


Phyllis DeGioia 
April 9, 2015

This is Phyllis DeGioia, editor of VetzInsight. I'm sorry to hear that you disliked the humor in Dr. Corp-Minamiji's article, and after your incredibly sad experience with your niece, I can see where humor might not be appreciated. Please understand that our main mission at VetzInsight is to deliver educational material with humor, as it's easier to learn when you're laughing. Humor makes reading easier. I assure you that none of us at VetzInsight think cancer is a light-weight subject, or funny. Dr. Corp-Minamiji lost a friend to sarcoma last year. I just finished radiation less than two weeks ago; my father had three types of cancer so it was stressful. In the middle of my treatment I drafted an article on cancer signs for our far more serious client education site, Veterinary Partner at, although it has Dr. Corp-Minamiji's byline. I do think of cancer as a cellular delinquent, hence the humorous reference to it. Both articles were reviewed by a veterinary oncologist. The dog in the photograph is mine, taken after his surgery, chemo, and radiation for anal sac cancer; his treatment gave me another third of his lifespan, even though he nearly died from two bad reactions to chemo.  Once again, we are all sorry to hear about your niece. My heart is with you and your family.

P Christiansen 
April 8, 2015

I was a care-giver to a 17-yr-old niece battling a Stage IV brain stem cancer. My dog IS my kid.  Dr. Christy's lax ('blur from a distant past'), candy-coated description of cancer in 1st two paragraphs is grossly inappropriate for the subject matter.  Her description of her studies as a 'rapidly spinning highlight reel' undermine her credibility. It's offensive: I want to hear about warning signs of this horrible illness from someone who: 1) treats the topic seriously & in a thorough manner 2) instills more confidence in her training & abilities to educate about prevention.

Linda Cummings 
March 23, 2015

I have pet insurance to cover my Daschund in the event he needs any kind of treatments.  I am very happy with [my pet insurance] as they cover 90% less the office visit and deductible.  Many of us would pay quite a bit to save our pets and I recommend [insurance]. [Editors' note: In accordance with VetzInsight's non-commercial comments policy, specific pet insurance names have been removed from this comment.]

March 23, 2015

Please add that owners should check lymph nodes regularly. Lymphoma is sudden and quick. Thanks.

March 23, 2015

I can't emphasize enough how important it is to take Christine's advise to heart. Our first beloved Westie -Duffy- seemed fine. Then his energy level suddenly went down and he had a hard time getting up on the couch. We soon learned he had testicular cancer that had spread within a matter of a few months. There was nothing we could do. Watch your older babies especially closely( Duffy was 12) for any changes. They will let you know.

March 20, 2015

My dog is pointer/walker hound and mostly white.  He developed a pea sized dark mole that I could feel on the side of his neck.  It was removed and it was precancerous.  He loves to sunbathe!  Now his time in the sun is limited.

Lillian Toll 
March 19, 2015

Every word Christine says is true.  My cat was given chemo for his cancer.  The most important things are our pets' comfort and gentle, loving care. That's all they ask of us and it is all we can give them.

Christine Holmstrom 
March 19, 2015

I agree - it's important to get an early diagnosis.  My experience has been that diagnosis can be difficult (I had a cat with stomach cancer) and treatments expensive and the curative effects can be short-lived.  Still, it's important to find out what's wrong in order to make an informed decision and reduce suffering.


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