Canine lung cancer is of 2 types: primary lung cancer, which is quite rare and metastatic lung cancer, spread from other areas of the body. The life expectancy of a dog diagnosed with lung cancer can be up to 22 months, depending on the type of tumor and on the treatment the dog undergoes.
Risks of Canine Lung Cancer
Primary lung cancer (i.e. the tumor originates in the lung tissue) is very uncommon in dogs (less than 1% of canine cancer cases).
As the condition is so rare, there are no studies with results to show the causes of lung cancer in dogs. However, it can be assumed that causes of canine lung cancer are not very different from the causes of human lung cancer (second-hand smoking and exposure to asbestos being among the top causes).
Statistically short and medium-nosed breeds are more prone to cancer. Probably, shorter noses retain fewer carcinogens from the environment, so these reach the lungs more easily).
In dogs already diagnosed with cancer elsewhere in the body, tumors are very likely to extend to the lungs, through blood circulation. When the cancerous cells reach the lungs, usually more than one tumor is present. However, the presence of several masses in the dog's lungs can also mean a fungal infection, so x-rays and biopsies are required to diagnose the cancer.
Both male and female dogs are exposed to lung cancer risks.
However, larger breeds and older dogs seem to be more predisposed to this type of cancer.
Improving Life Expectancy in Canine Lung Cancer
In primary canine lung cancer surgery is the first step (the affected lobe or sometimes an entire lung needs to be taken out).
Although dogs can live with only one lung, dogs with the left lung removed have fair better survival chances then those who had their right lung removed.
Dogs that have undergone this surgery can live from 2 to 22 months afterwards, depending on the size of the tumor and of the stage of cancer at the time of the surgery.
About 50% of dogs with lung cancer surgery have a life expectancy of 1 year.
To prevent the spreading of the cancerous cells, chemotherapy or radiation can be recommended.
In metastatic cancers, if the tumors have affected fewer lobes, surgery can be performed, even though it is normally not recommended with metastatic patients.
Antiangiogenic therapy can usually help such cases, by inhibiting the creation of new blood vessels in the affected area. Drugs such as ABT-510 can slow the cancer, but are still on veterinary trial.
Some veterinarians recommend chemotherapy with Deramaxx (a non-steroidal anti inflammatory drug) and an oral chemotherapy drug, cyclophosphamide (cytoxan). Combined, these seem to have the effect of inhibiting the formation of new blood vessels, so the tumor cannot grow.
As the cancer treatment will put the dog through a lot of pain, you should discuss things over with your veterinarian and oncologist to establish whether the time your pet is gaining is worth the suffering.