Skin Cancer In Canines & In Cats

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Arizona has the second highest cases of skin cancer in the world.  Australia is the #1 place for the disease. With this knowledge I regularly see a dermatologist to have my moles and my kids’ moles checked, but I hadn’t thought about our pets.  When our writer, Lisa Walton asked me if she could write about this and share her own dog’s story, I was very appreciative that she wanted to share to make us all aware of what to look out for when it comes to skin cancer and our beloved pets.  Lisa’s dog, Geo is doing well thanks to several things that Lisa did right in this situation, so read on and be aware…

Lisa says:

With my fair skin and freckles I’m hyper-sensitive about living in the Arizona sun.

I see my dermatologist for my annual skin check without fail.

But I wasn’t aware that my furry canine companion could get skin cancer too!


geo 2Three years ago we were blessed to adopt a black lab from the Desert Labrador Retriever Rescue of Phoenix.  Geo, is now 5 years old, and is the sweetest boy on the planet.  Many months ago I noticed a flat, flesh colored mole (about the size & shape of a pencil eraser tip) on his back leg.  While at a routine visit to our vet, I pointed it out.  At the time, she had no concerns.  Fast forward to the beginning of summer, and I happened to notice the same mole had become elongated, and flecked with raspberry bumps, difficult to really notice hidden by his black fur.  When we went back to the vet for his annual shots, I showed the mole to her again.  Initially, she had no concerns upon inspection, but when I explained how it had changed, she agreed that it should be removed.

Since it was so flat, a needle aspiration could not be done for a biopsy, so we scheduled a procedure to have it completely removed.  A week later our vet called to tell us that she was shocked to get the lab results back; that it was indeed Cancer.  After losing our other lab to Cancer, this was a devastating blow.  Fortunately, for our Geo these results were a best case scenario.  The grade of cancer was a 1; meaning there is no further treatment needed past surgery.  There is a 90% chance or better that this was an isolated case.  Secondly, the margins of the removed tissue all the way around the tumor were cancer-free, considered to be a Stage One (meaning it had not spread to any other tissue or organs).  Our vet commended us on how tuned in we are with our furry friend, and our vigilance contributed to his good prognosis.  Geo recovered from his surgery and is back to his happy playful self, we are relieved but will remain watchful.

Mast cell skin cancer is the most common in dogs.  Mast cell tumors in cats look very similar to those in dogs; they are allergy cells that induce itching, swelling and redness.  These tumors may be red, itchy and periodically swell up and then disappear.  Although dogs and cats who suffer from allergies are not more prone to developing mast cell skin tumors, certain breeds of dogs — including Labrador Retrievers, Boxers, Pugs and Golden Retrievers — are predisposed to developing this type of tumor.

Light-colored cats and dogs are more prone to skin cancers (carcinomas) that come directly from sunbathing, especially those that like to lay belly up exposing their thinly-haired tummies.  So limit your pet’s exposure to the sun and provide ample shade. Some breeds are more susceptible than others (especially on the tips of their ears, noses, bellies, or bodies that are shaved), and may require pet-safe sunscreen (consult with your vet).  If you find a lump or sore anywhere on your pet’s skin, see your veterinarian as soon as possible.

 As in almost any form of cancer in dogs, but especially with certain types of skin cancer, it is critical to identify and treat this disease in its early stages.  Examine your dog monthly by separating the hair with your fingers and closely look at the skin. Check for:

  • tumors, areas of color change, or scaly, crusty lesions.
  • new growths or a change in color or size of an existing growth
  • tumors that bleed easily or areas that do not tend to heal
  • an area the dog is continually licking or scratching
  • swelling in the breast tissue or discharge from a nipple
  • suspicious lumps or areas of discoloration under the tail
  • masses or tissue that seems different from surrounding areas in the mouth


About our writer, Lisa:


Lisa Walton–Parenting tips & Family Matters
Valley Teacher and Mother

Lisa Walton has been a teacher in the Valley for over 18 years. She holds a Bachelor’s Degree in Deaf Education from Illinois State University; and Master’s Degree in Special Education from Arizona State University. She currently works as an itinerant teacher, collaborating with regular education teachers in the public schools.

Read more about Lisa on our team bio page









  1. What a wonderful reminder that even our dogs can be at risk in our harsh Arizona sun. We actually sell a lot of our UPF 50+ rash shirts and sun visors for dogs. We also hear many stories of dogs with skin cancer (or other illnesses that make them more sensitive to the sun). Sun protective shirts and hats are a great way to keep your dog cool, protected (and cute!) in the summer sun. Thanks for a great reminder!

    • says:

      Thanks Gina! Good idea and I’m so glad that your company sells those items to protect our beloved pets.