Issue Description Lung cancer is a disease of uncontrolled cell
growth in tissues of the lung. This growth may lead to metastasis,
which is the invasion of adjacent tissue and infiltration beyond the
lungs. The vast majority of primary lung cancers are carcinomas of the
lung, derived from epithelial cells. Other Names Lung Cancer
Causes Canine lung cancer can be primary lung cancer
or metastatic lung cancer.
Primary lung cancer is defined as lung tumors that originate in the
lung. The tumors are almost always malignant and are usually
carcinomas (often adenocarnimas), although can be hemangiosarcomas.
The tumors are easily visible on a chest x-ray as one large solitary
mass. Primary canine lung cancer is rare but is aggressive and can
metastasize to the regional lymph nodes in the upper chest area.
Adenocarcinomas tend to spread to the central nervous system.
Metastatic lung cancer originates in other parts of the body such as a
leg bone, the mouth, or the thyroid gland, but has spread to the lung
through the bloodstream. Metastatic lung tumors usually present
themselves in multiples, not as a single mass.
Symptoms Initial signs of lung cancer, like all types of
cancers, tend to remain hidden, and the first signs usually surface in
the shape of problems with the canine respiratory system. Symptoms
like heavy breathing and chronic cough begin to appear. Frequent cough
that is deep and harsh with a lot of phlegm or blood is a sure sign
that there is a problem with the dog's respiratory system. The manner
in which lung cancer progresses depends largely on the type of tumor.
Sometimes the only way to really determine the specific type of
problem is to remove or obtain a piece of the malignant tissue for
Canine lung cancer normally occurs in older
dogs, and therefore there is a need to decide whether or not you want
to pursue with treatment at all. To be able to decide this, it is
necessary that you understand the kind of treatment that will be
required, the prognosis and the risks involved.
Diagnosis Cancer that is in the lungs tends to spread to
nearby lymph nodes. The lymphatic system is responsible for your dogs
immune system response. X-rays are taken to see if the lymph nodes are
enlarged from trapped cancer cells. Once these enlarged nodes are seen
then a veterinarian will take a sample for testing (biopsy).
Treatment If the veterinarian suspects your dog has
canine lung cancer, he may refer you to an oncologist who will be able
to provide specialized treatment. Treatment of the disease depends on
whether or not it has already begun to spread. If the disease is
localized to one area, treatment will usually involve surgery. If it
has already spread from other areas, canine lung cancer will have to
be treated with radiation or chemotherapy.
In the case of
primary lung cancer, surgery is the preferred treatment if the tumor
is small, because complete excision may not be possible in all cases.
Surgery is ruled out in cases of metastatic lung cancer. Chemotherapy,
after surgery or as a primary treatment choice, has shown good results
in controlling the progression of lung cancer. Lung cancer usually
proves to be fatal, and after treatment, you will be required to
provide extra home care to monitor the side effects of strong drugs
and provide comfort for as long as the dog lives.
Prognosis Dogs with small, low grade
(well-differentiated) tumors without lymph node involvement, the
average survival time is 16 months with surgery alone. Dogs with high
grade (poorly differentiated) tumors with lymph node involvement have
an average survival of 2 months. Because many patients will ultimately
develop metastatic disease following surgery, chemotherapy is commonly
recommended. However, it is unknown whether the use of chemotherapy
following surgery significantly improves survival over surgery alone.