Dogs with primary lung cancer can generally live up to one year after surgical removal of the mass in their lungs, provided the disease has not spread to the lymph nodes or other tissue, reports Canine Cancer. However, the dog's life expectancy is affected by the type of cancer, whether the dog was showing symptoms, and how advanced the cancer was at the time of surgery.
Primary lung cancer occurs in less than one percent of dogs, making it one of the rarest types of cancer to affect canines. It is almost always malignant, Canine Cancer says. Although experts generally agree that cancer is caused by mutations, there is thought to be a genetic component as well. Just like humans, dogs that live in homes where they are exposed to secondhand smoke are at higher risk for developing lung cancer. Because dogs with short to medium-length snouts are unable to filter carcinogens out of the air they breathe as effectively as longer-nosed dogs, they are more likely to develop lung cancer.
There are no breeds predisposed to developing lung cancers, but it is diagnosed more frequently among larger animals. Symptoms include coughing, lethargy, weight loss, loss of appetite and shortness of breath. However, up to 25 percent of dogs do not show any symptoms of respiratory illness at all.