Lung cancer in dogs may be primary, originating in the lungs or it may come from a different area of the body such as the liver, and then the cancer metastizes to the lungs. Primary lung cancer in dogs is rare and has four stages, and it is important to detect the condition as early as possible, to be able to administer treatment that may save your dog's life.
Stage 1 Lung Cancer
The canine cancer will have four stages. Even though primary lung cancer is rare in dogs and typically, the tumor originates elsewhere, reaching the lungs only in later stages, primary lung cancer is extremely aggressive and should be detected from stage 1 if possible.
During the first stage, the dog will have a tumor (most typically an adenocarcinoma), which will be small and won't affect any other organs, nearby tissues or blood vessels. The dog will present symptoms such as chronic coughing and lack of appetite. The dog may cough up blood, but not mucus. However, some dogs may not present any symptoms at all. At this stage, the tumor can be removed through surgery.
Stage 2 Lung Cancer
Stage 2 lung cancer will manifest through the growth of several smaller tumors that won't exceed 5 cm in length. The tumors will cause breathing difficulties and at this stage, the coughing will be upsetting. Surgery is still possible and the dog will have to get chemotherapy to prevent the development of new cancerous cells.
Stage 3 Lung Cancer
Stage 3 lung cancer can be detected through chest x-rays. At this stage, the dog will have several tumors, most of these larger than 5 cm. The tumors will also spread to the nearby tissues and blood vessels. The dog will display symptoms such as coughing blood and breathing difficulties, due to the tumors which may affect the trachea. Surgery is no longer an option, but the dog can get chemotherapy to delay metastasis. A lung transplant may be possible, but the surgery has several risks and may not be successful.
Stage 4 Lung Cancer
The tumor will metastasize in the chest in the blood vessels, tissues, bones and the neighboring lymph nodes. At this stage, the prognosis is poor and the dog doesn't have a lot of time left. The dog may need help to breathe and may also present lameness, because the cancer may extend to his limbs. You may administer at home care for your pet to make him more comfortable, but many vets will recommend euthanasia, because the dog will be in a lot of pain and even with pain medication, he will still suffer.
On average, lung cancer in dogs will metastize in 2 to 10 months, depending on when the tumor is detected and what treatment options are available or the strength of the animal to fight the disease. However, if surgery is possible and the tumors are completely removed, a total remission may be recorded.