Dog lung cancer is a disease of middle aged and elderly animals. This type of cancer may be primary or secondary. Primary lung cancer arises from tissues of the lung and airways, and tends to be a single, discrete mass. Secondary cancers have spread from tumors in other parts of the body. Malignant cells from bone cancer and mammary cancer can move through the lymphatic system and cause multiple small tumors throughout the lungs. The majority of tumors that are found in the lungs of dogs are secondary tumors.

25% of cases of dog lung cancer are asymptomatic; that means that the affected dog is showing no sign that there is a problem with their lungs. Their tumor shows up on a chest x-ray when they are being examined for an unrelated condition. A diagnosis of 肺癌第三期 comes as a terrible shock to their owner.

Dogs that live with smokers may be at increased risk of primary lung cancer.

Diagnosis

Animals affected with dog lung cancer can often show symptoms of lung disease, including a cough and difficulty in breathing. They are also less able to exercise, and become short of breath sooner than usual. As the disease progresses, they will lose weight and may regurgitate their food as the tumor presses on their esophagus.

X-rays of the chest of an affected dog will reveal either one single mass on one part of the lung, or a grainy appearance to all areas of their chest. If the tumor is on the outer part of the lungs, it may be possible to pass a needle into the mass, and take a sample of cancer cells. Other diagnostic methods include passing a bronchoscope down into the airways to take a biopsy of the tumor, or instilling sterile fluid into the windpipe and sucking it out, hopefully collecting some cells at the same time. These cells can be examined under a microscope to identify the type of tumor, and the likely prognosis.