How to Do a 10-Minute Cancer Check on Your Dog

Once a month, in about ten minutes, you can check your dog for the cancers that show up on the outside. Watch how they move, look in the mouth, feel three sets of lymph nodes, sweep both hands over every inch of skin, check the belly, weigh them, and write down what you found.

That is the whole thing. It is not complicated and it works, because you have your hands on your dog far more often than your veterinarian does, and the tumors that get caught small are the ones that get treated most easily.

Before you start, one honest limitation. A home check finds things you can see or feel. Several of the most serious canine cancers grow where your hands cannot reach, and a completely normal exam does not rule them out. Splenic masses often announce themselves as sudden collapse in a dog who seemed fine the day before, and definitive diagnosis of a splenic mass requires histopathology rather than any exam finding (Campbell, 2024). Roughly 90% to 95% of dogs with osteosarcoma already have microscopic spread at diagnosis, whether or not anything shows on chest radiographs (Luu et al., 2021).

So this is a supplement to veterinary care, not a replacement for it. Keep the wellness visits. Do this in between.

Key Points

Monthly is the right frequency for most dogs. Twice monthly is reasonable for breeds predisposed to skin tumors.

Only three sets of lymph nodes are reliably palpable in a normal dog: the mandibular under the jaw, the superficial cervical in front of the shoulder, and the popliteal behind the knee. Normal nodes are under 1 cm, often under half that, soft, and not painful (Verbrugghe et al., 2021).

If you cannot find your dog's lymph nodes, that is usually good news.

The rule to remember for lumps: a mass the size of a pea, meaning about 1 cm, that has been present for a month should be aspirated or biopsied rather than watched (Ettinger, 2022).

No one can tell what a lump is by looking at or feeling it, including an oncologist. Cancer is a cellular diagnosis (Ettinger, 2022).

Write down what you find, including where it is and how big. Memory is not a monitoring tool.

A normal home check is not evidence that your dog does not have cancer. It is evidence that you did not find anything on the surface this month.

Set Up First

Pick a time when your dog is calm and slightly tired. After a walk is ideal. A wound-up dog turns a ten-minute exam into a wrestling match, and you will rush and miss things.

Sit on the floor with your dog lying down or standing relaxed. Have treats. Keep your hands slow and flat rather than poking. Most dogs settle into this quickly because it feels like an unusually thorough petting session, which is essentially what it is.

You need one more thing: a place to write. A note on your phone works. So does a paper page taped inside a cabinet. Anything you will actually open again next month.

Minute 1: Stand Back and Watch

Before you touch anything, watch your dog move across the room.

You are looking for a limp that was not there before, stiffness getting up, a head that carries lower on one side, reluctance on stairs, a change in how they sit, or breathing that looks like effort at rest. Persistent lameness matters. Difficulty breathing matters. Both appear on the standard list of cancer warning signs (American Animal Hospital Association, 2026).

Lameness in a dog has a hundred causes and most of them are not cancer. It has one cause you do not want to miss, and limps that do not resolve get imaged rather than rested.

Minutes 2 and 3: Head and Mouth

Lift the lips on both sides and look. Then look at the roof of the mouth and, if your dog will allow it, under the tongue.

You are checking for any mass or growth on the gums, a bleeding or ulcerated spot, a tooth that has become loose in an area where the gum looks abnormal, or gum tissue that is darkly pigmented in a way that seems new. Sores that do not heal and abnormal bleeding or discharge are both on the warning-sign list (American Animal Hospital Association, 2026).

Also note bad breath that is new or noticeably worse, drooling that has increased, a dog dropping food or chewing on one side, or any asymmetry in the face.

While you are up here: check the eyes for a new bulge or a difference between the two, look at the nose for discharge or bleeding from one nostril, and check inside the ear flaps and around the ear openings.

Many dogs dislike having their mouths handled. If yours is one of them, do what you can without a fight and tell your veterinarian that the oral exam is the part you cannot manage. That is a normal thing to say and they will look for you.

Minute 4: Lymph Nodes

This is where owner guides tend to overcomplicate things by listing five sets of nodes to find. In a normal dog, three are reliably palpable: the mandibular nodes below the jaw, the superficial cervical or prescapular nodes in front of the shoulder joint, and the popliteal nodes behind the knee (Verbrugghe et al., 2021).

Under the jaw. Use your thumb and finger on each side, feeling below the jawbone toward the front. Mandibular nodes are usually more mobile than the nearby salivary gland and sit slightly further forward (Verbrugghe et al., 2021).

In front of the shoulder. Easiest with your dog standing. Feel over the front of the shoulder joint and press progressively deeper into the soft tissue there (Verbrugghe et al., 2021).

Behind the knee. Feel in the soft tissue behind the stifle on each hind leg. Most people find these the easiest of the three.

What you are assessing is size, texture, and pain. A normal node is under 1 cm and often under 0.5 cm, soft, and not painful when touched (Verbrugghe et al., 2021).

The single most useful thing about this step is symmetry. Compare left to right every time. One enlarged node on one side means something different from several enlarged nodes on both sides, and both are worth a phone call.

For dogs who have been treated for lymphoma, this check is part of routine follow-up, since increased lymph node size is typically how relapse is detected (North Carolina State University College of Veterinary Medicine, n.d.).

Minutes 5 Through 7: The Skin Sweep

This is the longest part and the highest-yield part.

Use both hands, flat, and move systematically so you do not skip regions. A workable route: start at the nose and work over the head and ears, down the neck, over the shoulders, along the back to the tail, then down each leg to the toes, then the chest, belly, and groin, then the tail itself and around the base of the tail.

Feel for anything raised, anything firm under otherwise normal skin, and anything that feels different from the same spot on the other side. Look as well as feel, particularly on thin-coated dogs and in places where the skin is pale.

The spots people miss: between the toes and around the nail beds, the armpits, the fold where the back leg meets the body, the inside of the ear flaps, under the collar, around the anus, and the tail base. Take the collar off for this.

Abnormal or rapidly growing swellings are a warning sign (American Animal Hospital Association, 2026). One caution on speed, though. A fast-growing lump on a young dog is often a cutaneous histiocytoma, a benign tumor that grows quickly by nature, which is exactly why growth rate alone cannot sort dangerous from harmless. Our article on cutaneous histiocytoma in dogs covers that one in full.

When you find something, be gentle with it. Note where it is, note roughly how big, and leave it alone rather than repeatedly squeezing or massaging it to see whether it has changed. Photographs with a coin beside the lump for scale are more useful than repeated handling.

Minute 8: The Underside

Roll your dog onto their side or back, if they tolerate it, and check the parts you never see.

Female dogs have two mammary chains running from the chest to the groin. Run your fingers along both, feeling for any firm nodule near a nipple. Mammary tumors are common and are often found by owners rather than at appointments.

Intact male dogs should have both testicles checked for a change in size, a difference between the two, or a firm area. Also look at the scrotal skin.

Every dog gets a look at the belly for distension or asymmetry, and a note if the abdomen seems larger or fuller than it was. Difficulty urinating or defecating belongs on this list too (American Animal Hospital Association, 2026).

Minute 9: Weight and Condition

Weigh your dog if you have a way to do it. If not, use your hands.

You should be able to feel ribs under a thin layer of covering without pressing hard, and see a waist when looking down from above. What you are tracking is change over months rather than an ideal number.

Weight loss and loss of appetite are both warning signs (American Animal Hospital Association, 2026), and weight loss in a dog eating normally is the version that deserves a prompt call. Gradual loss is easy to miss because you see your dog every day. This is exactly what the written log is for.

Minute 10: Write It Down

Record the date. Note anything you found, where it was, and its approximate size. Note the weight. Note anything about energy, appetite, drinking, breathing, or bathroom habits that has changed since last month.

If you found nothing, write that too. "Nothing new, 62 lb" is a complete entry and it is genuinely valuable, because it establishes that whatever you find in March was not there in February.

Take this log to appointments. Your observations between visits are information your veterinary team has no other way to get.

The Rule That Matters Most

Finding a lump is only half of the job. What you do next is the half that changes outcomes.

The guideline to remember comes from veterinary oncologist Sue Ettinger: if a dog has a mass the size of a pea, about 1 cm, and it has been there a month, get it aspirated or biopsied (Ettinger, 2022). Visual monitoring of superficial masses is not enough, and cytology or biopsy is what actually answers the question (Ettinger, 2022).

The reason is simple and worth stating plainly. Even an experienced cancer specialist cannot look at or feel a mass and know what it is. Cancer is a cellular diagnosis (Ettinger, 2022). When you or your veterinarian decide to watch a lump instead of aspirating it, you are not making an assessment. You are postponing one.

Two habits that undermine this rule:

Assuming it is another lipoma. A dog with a history of fatty tumors gets exactly the same treatment for a new lump as a dog with no history at all. Previous benign aspirates do not make the next one benign.

Assuming age settles it. A young dog's lump is not automatically harmless, and an old dog's lump is not automatically not worth pursuing. Cancer occurs across the canine lifespan, which our article on cancer in young dogs covers in detail.

What This Check Cannot Do

Being clear about this is part of doing it responsibly.

A monthly exam will not find a splenic mass, a tumor in the chest, a bladder tumor, a brain tumor, or bone cancer that has not yet caused a limp. Splenic masses in particular are known for presenting as sudden collapse from internal bleeding in a dog with no prior signs, and no exam finding substitutes for the histopathology that eventually gives the diagnosis (Campbell, 2024). The same limitation applies to microscopic spread, which is present in the great majority of osteosarcoma cases at diagnosis and is invisible on physical examination (Luu et al., 2021).

None of that makes the ten minutes less worthwhile. Skin, subcutaneous, oral, mammary, and lymph node cancers are a large share of what dogs get, and those are exactly the ones a pair of hands can find early.

It does mean that a clean home check is not a reason to skip a wellness visit, to decline recommended bloodwork, or to dismiss a symptom because you felt nothing last week.

When to Contact a Veterinarian

Book an appointment for:

Any mass about 1 cm or larger that has been present for a month, and any mass that is growing, changing, ulcerated, bleeding, or bothering your dog regardless of how long it has been there.

Any enlarged lymph node, particularly if several are enlarged at once.

A growth in the mouth, a non-healing sore anywhere, unexplained bleeding or discharge, or a loose tooth with abnormal surrounding gum.

Weight loss without a diet change, ongoing appetite loss, or persistent lethargy.

Lameness that does not resolve, or a firm swelling on a limb.

Difficulty eating, swallowing, breathing, urinating, or defecating.

Seek emergency care for collapse, pale gums, a distended abdomen with weakness, sudden severe difficulty breathing, or a seizure.

If you are unsure whether something warrants a visit, call and describe it. That call is free and the answer usually takes a minute.

Questions to Ask Your Veterinarian

Can you show me where my dog's lymph nodes are so I know what normal feels like?

Can we aspirate this lump today rather than monitoring it?

Given my dog's breed and age, what should I be checking for specifically, and how often?

What is my dog's current weight, and what change would concern you?

Are there spots on my dog that are hard for me to check that you should look at?

How often should my dog have a full physical exam, and does that change with age?

Would routine bloodwork or imaging be worth adding at my dog's age?

Sources

American Animal Hospital Association. (2026, April 29). How common is cancer in dogs? Risk and early warning signs. https://www.aaha.org/resources/canine-cancer/

Campbell, B. G. (2024). Splenic masses in dogs: Algorithms for differentials, diagnosis, and definitive treatment. Today's Veterinary Practice. https://todaysveterinarypractice.com/soft-tissue-surgery/splenic-masses-in-dogs-differentials-diagnosis-and-treatment-algorithm/

Ettinger, S. (2022). Veterinary oncology: What to do with lumps and bumps on dogs and cats. Today's Veterinary Practice. https://todaysveterinarypractice.com/oncology/tumor-detection-dogs-cats/

Luu, A. K., Wood, G. A., & Viloria-Petit, A. M. (2021). Recent advances in the discovery of biomarkers for canine osteosarcoma. Frontiers in Veterinary Science, 8, Article 734965. 

North Carolina State University College of Veterinary Medicine. (n.d.). Medical oncology: Canine rescue lymphoma. NC State Veterinary Hospital. https://hospital.cvm.ncsu.edu/services/small-animals/cancer-oncology/oncology/canine-rescue-lymphoma/

Verbrugghe, A., Defarges, A., Phillips, E., Gaitero, L., Abood, S., Raheb, S., & Blois, S. (2021). Peripheral lymph nodes. In Clinical medicine 1: Small animal clinical skills textbook. University of Guelph. https://books.lib.uoguelph.ca/vetm3430/chapter/peripheral-lymph-nodes/