Treating Lung Cancer in Dogs with Chemotherapy

Cancer in dogs is surprisingly common. Dogs can get many of the same type of cancers that can afflict humans, including lung cancer. Many of the same treatment options available to humans with lung cancer, like chemotherapy, are available to dogs with lung cancer.

Lung Cancer in Dogs

A dog’s environment is thought to be the primary cause of lung cancer. Second-hand cigarette smoke can greatly increase the risk of lung cancer in a dog, especially in dogs that have short or medium-length snouts. Medium and large older dogs have been diagnosed with lung cancer more than smaller breeds. The primary symptoms of lung cancer in dogs are coughing, difficulty breathing, shortness of breath, lack of energy, weight loss, and loss of appetite.

A dog can be diagnosed with two different types of lung cancer: primary lung cancer and metastatic lung cancer. Primary lung cancer is when the tumors begin in a dog’s lungs. This type of cancer is rarer in dogs and the tumors look like a large mass in an x-ray. Metastatic lung cancer is when the cancer begins in another part of a dog’s body and spreads to the lungs through the bloodstream. The cancer can originate in a bone, the mouth, thyroid, etc. and it is not uncommon for the cancer to spread to a dog’s lungs. A dog with metastatic lung cancer will usually present with several nodules in his lungs.             

Treating Lung Cancer in Dogs with Chemotherapy

After a thorough examination and diagnosis of lung cancer has been made, a veterinary oncologist may choose to treat the cancer with chemotherapy, especially if the cancer has spread or surgery is not an option.

Chemotherapy is when a dog with cancer is treated with cytotoxic drugs that damage the cells that divide and spread. The dose of medications used is based on the size of the dog and the minimum dose is typically administered in order to reduce the side effects of the chemotherapy.

Chemotherapy treatments last about eight weeks with the medications being administered every other week. Dogs undergoing chemotherapy have to be monitored closely and are usually hospitalized during treatment because the drugs used can be dangerous. The side effects of chemotherapy include a weakened immune system, a higher rate of infection, heart problems and bladder problems.


A dog with lung cancer can live anywhere from 2 months to 2 years after being diagnosed depending on the type of cancer, how advanced it is, and symptoms presented. The prognosis for dogs with primary lung cancer is usually better than dogs with metastatic lung cancer as masses in the lungs that have not spread can be removed surgically. However, the prognosis for dogs with metastatic lung cancer is not very good. In these instances, pet owners can help their dog by keeping him comfortable and has a good quality of life for as long as possible.

After chemotherapy treatments for lung cancer, remission can last up to 24 months. Chemotherapy will not always cure a dog of cancer, but can help control it.