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The disease

Canine nasal adenocarcinoma

The most common cancer of a dog's nose and sinuses. It grows slowly and quietly, it is often mistaken for allergies or infection, and it is usually found late. Here is what families should know.

Video in production. Captions and a full transcript will publish with it.

Video explainer

Four minutes to understand the disease

An animated walkthrough of a dog's nasal anatomy, how the tumor grows, how it's diagnosed and the treatments available today.

  1. Inside a dog's nose

    Turbinates, sinuses and the thin bone that separates the nose from the brain.

  2. How the tumor grows

    Adenocarcinoma starts in the glandular lining and spreads locally into bone.

  3. The warning signs

    One-sided discharge, nosebleeds, sneezing and noisy breathing.

  4. Getting a diagnosis

    Why a CT scan and biopsy are the keys.

  5. Treatment and hope

    Radiation today, and the frontier research that could change the outlook.

What it is

A local cancer in a crowded space

A dog's nasal cavity is packed with scrolls of thin bone called turbinates, which warm and filter air and carry an enormous sense of smell. Nasal adenocarcinoma begins in the glandular cells that line this space.

The tumor is locally aggressive. It destroys turbinates and bone as it grows, and it can push into the sinuses, the eye socket, or through the cribriform plate, the thin bone between the nose and the brain.

It is slow to spread elsewhere. At diagnosis, most dogs have no detectable spread to the lungs or lymph nodes. Most of the harm comes from local growth, which is why treatment focuses on controlling the tumor where it is.

Adenocarcinoma is one of several carcinomas that occur in the nose; others include squamous cell and undifferentiated carcinomas. Sarcomas such as chondrosarcoma, and lymphoma, account for most of the rest.

Side view diagram of a dog's skull showing the nasal cavity, turbinates, frontal sinus, cribriform plate and brain, with a tumor in the nasal cavity Brain Tumor in nasal cavity Turbinates Frontal sinus Cribriform plate Nostril
Simplified side view. The tumor destroys the fine turbinate bones as it grows and can erode through the cribriform plate toward the brain.

Who gets it

Any dog can, but some are at higher risk

Age

Middle-aged to older dogs

Most dogs are diagnosed around 9 to 10 years old, though it can occur younger.

Size & skull shape

Medium and large, long-nosed breeds

Dogs with long muzzles (dolichocephalic breeds) are overrepresented, likely because they have more nasal surface to filter inhaled particles.

Environment

Indoor air exposure

Studies link secondhand smoke and indoor combustion, such as some heaters and stoves, to higher risk. See causes & prevention.

Why it's so challenging

The signs look like everyday problems

Early signs, like sneezing, discharge and a stuffy nose, look like allergies, a tooth root infection or a foreign body. Dogs often get antibiotics or allergy medicine first, and the signs may improve briefly before they return.

By the time a nosebleed or facial swelling appears, the tumor has usually filled much of the nasal cavity. Seeing it takes a CT scan under anesthesia, and confirming it takes a biopsy, so it can take weeks or months to reach a diagnosis.

The location makes treatment hard too. The tumor sits next to the eyes and brain, so surgery alone can't remove it cleanly. That is why radiation, and more precise radiation, is at the center of care.

Typical path to a diagnosis: early signs treated as allergies or infection, brief improvement, signs return, nosebleed or facial swelling, CT scan under anesthesia, then a biopsy, often weeks to months after the first signs Sneezing, discharge, stuffy nose Looks like allergies or a tooth or sinus infection Antibiotics or allergy medicine Signs often improve for a while Signs return Often on one side of the nose Nosebleed or facial swelling The tumor has usually filled much of the cavity CT scan under anesthesia Shows the size and spread of the mass Biopsy confirms the diagnosis Then treatment planning begins WEEKS TO MONTHS
A typical path to diagnosis. Early signs mimic common problems, so the tumor is often advanced by the time it is found.
When to ask about a CT scan

If your dog has discharge or bleeding from one nostril, sneezing that doesn't resolve with treatment, or any swelling of the face or nose, ask your veterinarian whether advanced imaging is warranted.

See the full symptom list →

Causes & prevention

What we know, and what we're still learning

No single cause has been proven. Research points to environmental exposures that owners can reduce today.

Moderate evidence

Secondhand smoke

A case-control study found higher nasal cancer risk in long-nosed dogs living with smokers. Keep smoke away from your dog, indoors and in the car.

Limited evidence

Indoor combustion

Penn-affiliated research associated exposure to some indoor heaters and fuels with sinonasal cancer. Ventilate well and service wood stoves, kerosene and coal heaters.

Under study

Genetics & biology

Researchers are studying tumor genetics and the immune environment to explain why some dogs develop it and how to find it earlier.

Read the studies →Quick reference guide →