No pet parent wants to hear that their dog has cancer. If your dog has been diagnosed with lung cancer, you may be filled with questions. What causes lung cancer in dogs? Can dogs recover from lung cancer? Here's the basic information about this type of cancer in dogs to help you better understand the path forward.
How is Lung Cancer Classified?
So, what causes lung cancer in dogs? There's no straightforward answer. Lung cancer may arise from a variety of environmental and genetic risk factors, one of which is age. Lung cancer in dogs is divided into two broad categories: primary lung cancer (which means the cancer started in the lungs) and metastatic lung cancer (which means the cancer spread from another part of the body to the lungs).
Primary Lung Cancer
Primary lung tumors are rare in dogs, with adenocarcinoma being the most common type. According to the Merck Manual, most primary lung cancer is diagnosed in older dogs between 10 and 12 years of age. There's no breed or sex predisposition. About 80% of primary lung tumors in dogs are malignant and regrow after treatment or spread to other parts of the body, including the lymph nodes, bones, brain and other parts of the lungs. Coughing is a common sign of primary lung cancer.
Metastatic Lung Cancer
Metastatic lung cancer is more common in dogs than primary lung cancer. Cancer often spreads to the lungs because all the blood in the body goes through the lungs, and blood can carry cancer cells. The lymphatic system or tumor cells in other organs near the lungs can also spread metastatic lung cancer. Can dogs recover from lung cancer if it's metastatic? Because cancer typically spreads to the lungs in late-stage cancer, unfortunately, the answer is usually no.

What Are the Signs of Lung Cancer in Dogs?
Coughing is one of the most common signs of primary lung cancer due to a tumor pressing on and irritating airways. Dogs with metastatic lung cancer may also develop a cough but not always. In some cases, your dog may show no signs at all. Other signs of lung cancer can include:
- Difficulty breathing
- Panting
- Coughing up blood
- Weight loss
- Decreased appetite
- Lethargy
- Fever
- Signs associated with cancer in other parts of the body, including increased thirst and urination and lameness due to bone cancer
Seek veterinary care if your dog exhibits any of these signs. While they may indicate lung cancer, many conditions can share the signs of lung cancer. Your veterinarian can help determine your dog's condition so you can get the best available care for them.
How Is Lung Cancer in Dogs Diagnosed?
Your vet will use several tools to determine whether your dog's signs are caused by lung cancer or something else. They'll likely ask you about your dog's history and conduct a full physical examination, including listening to their heart and lungs and taking vitals (heart rate, respiratory rate and body temperature). They'll likely use one or more diagnostic tools to further determine the cause of your dog's condition. These often include:
- Chest radiographs (X-rays)
- Blood and urine tests, including heartworm testing and clotting profiles
- Fecal testing for parasites
Your vet may order additional tests depending on the initial results. These may include advanced imaging with abdominal ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and chest taps or tissue biopsies for samples to send to the lab.