Dog: Lung Cancer

General information

Other common/scientific names: lung tumors, pulmonary neoplasia

A dog has two sets of lungs on either side of the chest cavity. They surround the heart and fill most of the chest between the base of the neck and the diaphragm. Each set of lungs are made up of lobes or sections. The right lung has four lobes and the left lung has three. The lungs are responsible for taking in oxygen and eliminating waste gases like carbon dioxide.

Lung cancer in dogs can be either primary (originating in the lung) or metastatic (originating in another organ and spreading to the lungs). While primary lung cancer is uncommon in the dog, it is usually a malignant type known as a carcinoma. The cause of primary lung cancer is unknown although there may be an increased risk in dogs exposed to second hand smoke. Primary lung cancer is usually diagnosed in older dogs (over 11 years) and in medium to large sized dogs.

Metastatic lung cancer in more common than primary. Malignant cancer cells spread through the body via the bloodstream or lymphatics. Mammary cancer, bone cancer (osteosarcoma), hemangiosarcoma and oral melanomas are cancers which commonly spread to the lungs from other areas. Tumors may be single or multiple masses, diffuse (widely spread throughout the lungs) or as a consolidated lobe. Lung cancer can also involve the pulmonary lymph nodes.

Cardinal symptom

Chronic cough


A chronic, nonproductive cough is most common sign of lung cancer. Other signs will depend on where the tumor originated and include lethargy, trouble breathing, weight loss, coughing up blood and lack of appetite.


While lung cancer can be initially diagnosed on radiographs, a tissue sample is needed for confirmation of cancer. If the tumor is accessible with a needle, a fine needle aspirate can be used to obtain cells. Cells can also be obtained by flushing the trachea or with a bronchoscope. These procedures are best performed by an experienced veterinarian at a specialty clinic. If metastatic disease is suspected, abdominal radiography, ultrasonography and bloodwork is needed to assess other internal organs.

Abb. GG95VMIT: Lung Cancer.
This is a radiograph of a dog with metastatic lung cancer in a diffuse pattern. The black arrows point to multiple small areas of cancer. Heart (A).

Abb. GG95WZ10
Abb. GG95WZ10: Lung Cancer.
This is a radiograph of a dog with a single, large tumor (B) between the heart (A) and the diaphragm (C).


Treatment will depend on the type of cancer present in the lungs. Surgical removal of the cancerous lung lobe or tumor is the treatment of choice. However, complete removal may not be possible. Inoperable tumors or metastatic disease may be controlled or slowed with chemotherapy.


If the tumor can be completely removed, the survival time for dogs is 15-26 months. Lymph node involvement or multiple tumors shorten the survival time. Recurrence is common and metastatic disease carries a grave prognosis.

Update version: 4/24/2014, © Copyright by
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