An Informative Guide To Canine Lung Cancer

There are basically two popular forms of canine lung cancer.  The first type is a primary form of lung cancer which is characterized as tumor masses that begin growing within the dog's lung tissue.  The second form is a metastatic lung cancer that has originated in other areas of the body such as the dog's mouth, thyroid gland or bones in the legs, but it has spread by traveling through the blood stream to turn into canine lung cancer.

The primary form of canine lung cancer is fairly uncommon and in the past has made up far less than one percent of all cancer statistics in the past but this number has been on the rise.  The reason for the drastic increase is unknown but it is believed to be either due to an increased number of cancer cases overall or that there are just now improved ways for veterinarians to diagnose these tumors.  Canine lung cancer tumors are most often malignant and usually appear as a solitary, large mass in the lung on an X-ray.

There are also metastatic lung tumors which are spread from a tumor somewhere else in the dog's body.  This commonly occurs in dogs that are suffering from bone cancer.  These types of tumors are generally found in multiple masses and not as one single mass like in other tumors.  You should be aware that affected dogs that have multiple masses could also be suffering from a type of fungal infection and not from cancer.  This is why it is so important to be sure that your dog has received an accurate diagnosis in either case so proper treatment can be initiated.


Canine lung cancer can be a direct result of the environment that your dog lives in.  Secondhand smoke is as dangerous to dogs as it is to humans.  It has been associated with nasal and lung cancer in dogs, lung cancer in birds and lymphoma and oral cancer in cats.  It is also proven that dogs that have short noses or medium length noses are much more vulnerable to canine lung cancer since the nasal passages are not as effective at accumulating all of the carcinogens in the inhaled secondhand smoke.  This results in a considerable amount more of carcinogens reaching the dog's lungs.  Lastly, there is also a form of cancer that is called mesothelioma that is present in the lung's lining that is caused from asbestos, similar to humans.

Risk Factor

Male and female dogs are equally susceptible to canine lung cancer.  There is however, a bit of an increase reported in risk factors in those dogs that live in urban areas.  Lung cancer seems to be more common in large and medium-sized, older dogs that are an average of 11 years old as well as dogs with short noses.


Symptoms of canine lung cancer include coughing that often produces blood or phlegm, exercise intolerance and lethargy, loss of appetite or weight loss, difficulty breathing and shortness of breath.  Chronic cough is the most common symptom noted in almost all cases.  If the tumor happens to be large, causing compression on either the trachea or another major airway, the dog will experience difficulty breathing.

Clinical signs can often be vague and not even specific at all to the respiratory tract.  It is reported that around 25 percent of dogs that have lung cancer will not show signs of illness.  Other affected dogs will show signs of lameness or they may limp when walking since the tumor can spread to the bones and affect their growth.  Other symptoms of canine lung cancer include pneumonia, heart failure, heartworm infection, metastatic cancer, fungal infection, collapsing trachea and lung worms.