Lung cancer is disease that needs to be taken seriously and detected early. Lung cancer can be either metastatic or primary in dogs. No one gender or breed is more prone to it than another; however, just like with humans, if the dog is continually exposed to second-hand smoke, its risk of developing the disease increases significantly. Lungs are of course a key component of life, with the responsibility of supplying oxygen to the bloodstream.

Metastatic lung cancer means the cancer itself has begun somewhere else in the body, rather than the lungs. In most cases this type of lung cancer will involve multiple masses on the lungs. It could have developed at any place in the body such as the thyroid gland, the mouth, or the leg bone. The cancer then went on to spread through the bloodstream to the lung.

Primary lung cancer refers to cancer that began in the lung tissue. This form is much more rare; however, it is extremely aggressive and can metastasize quickly throughout the body. In most cases they are carcinomas, which means they cancerous. They may have started in airways, the lung tissue, or bronchioles. When an x-ray is done on the chest, it will appear as one giant mass.

Although the exact cause of lung cancer cannot be pin-pointed, it has been shown that those dogs that are exposed to second-hand smoke on a regular basis are at much higher risk of developing the disease. Besides second-hand smoke, living in an urban city setting may also play a factor due to the pollutants in the air.

Another factor that can contribute to the development of lung cancer is exposure to asbestos. This actually causes a very specific form of cancer called mesothelioma.

Cancer itself is a mutation in the cells or damaged cells. Why this happens in some and not others still isn’t known.

Due to the fact that the causes are largely unknown, there isn’t a lot an owner can do to prevent lung cancer in his or her dog. The best prevention method is to be sure your dog is not exposed to environmental factors on a regular, on-going basis.

In one-quarter of the cases, dogs with lung cancer will show no symptoms so it is sometimes a hard disease to detect early. Symptoms may include one or more of the following:

  • fever;
  • pain;
  • rapid breathing;
  • poor appetite;
  • difficulty breathing or a shortness of breath;
  • lethargy;
  • muscle wasting;
  • slow weight loss;
  • lameness;
  • coughing up blood;
  • a buildup of fluid in the abdomen; and
  • a persistent/chronic cough.

Dogs at Risk
For dogs exposed to cigarette smoke on a regular basis are more at risk to develop lung cancer. Short-nosed breeds are at a higher risk than those that are long or medium-nosed. The reason for this is that these breeds have a shorter nasal passage which doesn’t do a good job preventing the carcinogens from entering the lungs when inhaled. The gender of the animal plays no role but age is usually a factor, with it commonly occurring in older dogs. It is also believed that those dogs living in an urban environment are more at risk.

Testing and Diagnosis
After a physical examination is done on the dog, the veterinarian will need to conduct blood work and most x-rays of the chest. The blood work will include a biochemical profile as well as a CBC (complete blood count). Other tests may include a urinalysis so the veterinarian can see how the kidneys are functioning and an ultrasonography of the abdominal area. MRIs and CT scans are used when it is believed the tumour has spread to other areas of the body. A fine-needle aspirate of the mass in the lungs may be needed for a more complete picture. If a lung mass has been discovered, a biopsy will be taken to determine the diagnosis. All of these methods will help to determine if the dog in fact has lung cancer, what stage it is at and where it’s located.

Treatment and Prognosis
Treatment will differ from case to case. Surgery is a common first step to remove a lung tumour that is still localized, or is still primary lung cancer. Sometimes surgical removal isn’t possible though, so other treatment options will need to be discussed.

Other treatment methods may include radiotherapy and chemotherapy. Even if surgery was performed, it may still be necessary to include these forms of treatment. They are used to prevent the spreading of the cancer or to slow it down.

In the case of metastatic lung cancer, chemotherapy and radiation will be used. Because the cancer is no longer localized to one spot, surgical removal is not possible.

Prognosis varies on what type of cancer the dog has. For those with primary lung cancer, if the cancer hasn’t spread and was just a single, small mass, prognosis should be good. In general though, no matter what type of lung cancer the dog has, expected life span will range from two months to two years.