I found the lump on Cooper’s gum on a Tuesday in March. I’d actually been doing an oral check — something I’d started doing casually after reading about dog dental health — and there it was. A small, dark, raised spot near his back teeth. It hadn’t been there the month before. I called the vet that afternoon.
It was oral melanoma. Stage two. He was eight years old.
I am not sharing this to scare you. I’m sharing it because catching it at stage two instead of stage three or four gave us almost a year more together than we otherwise would have had. And I found it because I was looking. Most dog owners don’t know what to look for, or never think to look at all. That changes today.
Cancer is the leading cause of death in dogs over age ten. Approximately one in four dogs will develop some form of cancer in their lifetime — and certain breeds (golden retrievers, boxers, rottweilers, bernese mountain dogs) face dramatically higher risk. Early detection isn’t guaranteed to change outcomes, but it matters enormously for options and quality of remaining time.
The Monthly Check: What to Look For
1. Lumps, Bumps, and Changes in Existing Masses
Run your hands over your dog’s entire body once a month. Feel for any new lumps, bumps, or swellings — under the skin, along the jaw, in the armpits, groin, and along the belly. Not all lumps are cancer (many are lipomas — harmless fatty deposits), but any new lump should be evaluated. More importantly, watch existing lumps for rapid growth. A lump that doubles in size over two to four weeks is a red flag that needs immediate vet attention.
2. Changes in the Mouth
This one saved Cooper some time. Lift your dog’s lips and look at the gums, teeth, tongue, and the roof of the mouth. You’re looking for: unusual color changes, dark or discolored spots, raised growths, sores that don’t heal, or foul odor that seems different from normal dog breath. Oral tumors can grow rapidly and are often missed because owners don’t look in their dog’s mouth regularly.
3. Unexplained Weight Loss
If your dog hasn’t been on a diet and is losing weight, take it seriously. Unexplained weight loss — especially more than 10% of body weight — is one of the most common early signs of cancer. It can also signal other serious conditions, but it should never be written off as “just getting older.”
4. Persistent Sores or Wounds That Don’t Heal
A wound that won’t close after two to three weeks, or a sore that keeps reopening, can indicate that something is affecting your dog’s immune function or that there’s abnormal tissue growth. Don’t wait it out — get it seen.
5. Bleeding or Unusual Discharge
Bleeding from any orifice — nose, mouth, ears, vulva, or rectum — that can’t be explained by an obvious injury is worth an urgent vet call. Same with unusual discharge that’s bloody, discolored, or has an abnormal odor. These can be signs of tumors affecting internal tissues.
6. Changes in Eating or Swallowing
Sudden difficulty eating, reluctance to chew on one side, dropping food, or pawing at the face can indicate mouth pain from a tumor. Changes in appetite that don’t have another obvious explanation — illness, medication, stress — should be noted and reported to your vet.
7. Coughing or Breathing Changes
A persistent cough — especially a dry, honking cough in a dog that wasn’t previously coughing — can indicate lung masses or fluid accumulation in the chest. Labored breathing, rapid breathing at rest, or unusual exercise intolerance can also signal cardiac or pulmonary tumors. These symptoms also overlap with heart disease, which is equally serious.
8. Lameness or Difficulty Using Limbs
Bone cancer (osteosarcoma) is tragically common in large and giant breeds. It often presents as lameness in one leg, swelling around a joint, or pain on palpation that doesn’t respond to typical arthritis treatment. If your large dog develops a sudden limp that doesn’t improve with rest, ask your vet to rule out bone involvement.
9. Swollen Lymph Nodes
Lymph nodes are located under the jaw, in front of the shoulders, under the armpits, in the groin, and behind the knees. When they’re enlarged and firm — not just temporarily swollen from fighting an infection — they can indicate lymphoma, one of the most common cancers in dogs. Learn where your dog’s lymph nodes are and check them monthly as part of your body scan.
10. Changes in Bathroom Habits
Straining to urinate or defecate, blood in urine or stool, and sudden changes in bowel consistency can all indicate tumors affecting the urinary tract, colon, prostate, or reproductive organs. If your dog is straining or if you notice blood, don’t wait more than a day or two to call your vet.
How to Do Your Monthly Check
Set a date — the first of every month, or tied to something you already do. Get your dog comfortable (treat rewards help). Systematically work from nose to tail:
- Mouth and gums — lift the lips, look at all surfaces
- Lymph nodes — jaw, shoulder, armpits, groin, knees
- Body surface — both hands, slow strokes over the entire coat
- Belly and groin — feel for firm masses or asymmetry
- Legs and paws — check between toes, feel along bones
- Tail and rear — note any swelling or discharge
Write down anything you notice. Take a photo of any lumps with something for scale (a coin, a ruler). This documentation is invaluable when you go to the vet.
When to Call the Vet Immediately
Don’t wait for your next annual exam if you find: a lump that’s growing rapidly, unexplained bleeding, a dog who suddenly can’t bear weight on a limb, or a dog who seems to be in significant pain. Cancer treatment outcomes are dramatically better with early intervention. Your instinct that something is wrong is worth a phone call.
The Takeaway
You know your dog better than anyone. Monthly body checks take five minutes and could give you months or years. Make it a habit — not out of fear, but out of love. Cooper gave me that lesson. I’m passing it to Birch, and now to you.