Metastatic Lung Cancer in Dogs

Cancers in dogs can appear on almost any type of tissue, both internal and external. In addition to their location, these cancers can vary greatly in terms of their spread and lethality. By their nature, cancers involve the abnormal growth of cells which often result in the appearance of solid tumors. Some cancers do not always result in solid tumors. This is the case with leukemia and other blood cancers. Not all types of dog tumor are cancerous.

As the cancer cells proliferate, they spread to neighboring tissues. This normal growth is known as cancer invasion and is distinct from metastasis. When a cancer metastasizes, the cancer cells are able to break into the circulatory or lymphatic systems. These systems spread the cancer cells to other parts of the body to create a secondary tumor, also known as a metastatic tumor.

When the metastasis occurs through the dog's respiratory system into the lungs, it is known as metastatic lung cancer. This is different from primary lung cancer which is less common. It is interesting to note that these cancer cells are more similar to those from the primary tumor rather than those of the secondary location. Metastatic lung cancer is a common form of metastasis since the lungs process a large amount of blood in the dog's organism.

The possibility of metastasis is something which distinguishes malignant tumors from other types of benign canine tumor. It can greatly affect how the dog responds to the cancer, particularly in terms of prognosis and life expectancy.

The life expectancy of a dog diagnosed with lung metastasis depends on several factors. These include the following:

• The type of primary cancer and its severity.
• The general health of the dog.
• The degree of advancement of the metastasis in the lungs.

Dogs with advanced metastatic lung cancer, aggressive primary cancer and poor overall health will have a shorter life expectancy. This is when compared to dogs with less advanced metastases, a more treatable tumor and are of a better physical condition.

When dogs receive treatment with surgery, chemotherapy or radiation therapy, they may experience an improvement in their quality of life, symptoms and even life expectancy. This will always depend on the specific case and the most appropriate treatment based on the type of primary tumor.

In summary, the prognosis for metastatic lung cancer in dogs is guarded. Generally, most dogs diagnosed with lung metastasis secondary to another type of tumor have a life expectancy of weeks or a few months. This can vary depending on the dog's health, as the better their condition, the better they will tolerate treatment. The severity of the metastasis also plays a role, with less advanced cases being more promising.

If no treatment is given or if the cancer is very advanced, most dogs die within weeks. With proper treatment, some dogs with metastatic lung cancer can live between 6 and 12 months. Life expectancy may even be longer if the metastasis is very localized, the dog is in good health and the primary tumor is not too aggressive.

However, it is important to note that metastatic lung cancer in dogs is almost always terminal. It is very rare for any type of remission to occur, although treatment may extend lifespan. This is why it is vital we monitor the dog's quality of life and best ensure they are not suffering.

Whether primary or secondary, lung cancers can result in various symptoms in the dog. Learn about one of the most concerning with our article explaining pulmonary edema in dogs.

We've already discussed what determines the life expectancy of a dog with a metastatic lung tumor. The main factors that influence how the disease progresses and how the dog responds to treatment include the following:

• Size and severity of the metastasis: if the metastasis is localized to specific areas of the lungs, it can be treated with surgery or radiation therapy. This will often result in a better prognosis, but treatment is not always an option. Widespread or disseminated cancers have a more guarded prognosis.
• Primary cancer type: some tumors are more aggressive than others and tend to metastasize more quickly or extensively. Common examples include osteosarcoma, melanoma, lymphoma and breast cancer in dogs.
• Primary cancer stage: the prognosis and life expectancy are better when the primary tumor is diagnosed and treated in its early stages. Treatment is much more difficult when it is already very advanced and lung metastasis is extensive.
• Response to treatment: if the dog responds well to radiation therapy, chemotherapy or surgery (depending on the type of tumor), tumor growth can be controlled and symptoms reduced. This can improve life expectancy.
• General health of the dog: if the dog is strong and healthy, it should positively influence their life expectancy. Dogs with previous kidney, liver or heart problems are less likely to respond well to treatment due to their more compromised health.
• Dog's age: in general, younger dogs tend to respond better to treatment than older dogs. This also positively influences prognosis and life expectancy.

Even if senior dogs respond to treatment, it may reduce their quality of life significantly. In these cases, guardians will need to consider whether it is time to euthanize the senior dog for humane reasons.

Lung cancer in dogs does not always present obvious symptoms, especially in early stages. This is not the case with metastatic lung cancer. Metastatic canine lung cancer typically presents noticeable symptoms, even if they are misattributed to another cause. The spread of cancer cells to different organs and tissues can aggravate symptoms and further deteriorate the dog's health. Some of the signs of metastatic lung cancer in dogs include:

• Dyspnea or respiratory distress: usually with labored, rapid or shallow breathing, often accompanied by stridor or wheezing due to airway obstruction. In addition to cancer, you can learn about other reasons senior dogs cough or gag with our related guide.
• A chronic, dry or productive cough: may contain blood or mucus if the tumor has invaded the blood vessels. This cough often worsens and becomes more frequent over time.
• Extreme fatigue or tiredness: the dog refuses to participate in everyday activities such as walking or playing, and resting more frequently than usual.
• Loss of appetite or anorexia: leads to significant weight loss, aggravated by the high energy expenditure required by the body to fight cancer.
• General pain and discomfort: may manifest as changes in behavior, irritability, or restlessness.
• Bleeding or discharge from the nose: when the tumor has reached the upper respiratory tract and invaded the nasal passages, you may see blood coming out of the dog's nose.
• Cyanosis: a bluish coloration or paleness of the dog's mucous membranes, caused by a lack of oxygen in the blood due to respiratory failure.
• Difficulty resting: pain and shortness of breath prevent the dog from finding a comfortable position to sleep or relax.

We have already explained there are various factors which contribute to the life expectancy of a dog with metastatic lung cancer. These include that which we cannot change, such as the dog's age or the type of primary cancer. Life expectancy can generally be improved if the diagnosis is made early, the metastasis is localized and the dog is strong enough to tolerate chemotherapy treatment.

Unfortunately, there is not much we can change to influence these factors. We can ensure their basic needs are met. This includes not only providing food, but encouraging them to eat even when they lose appetite. This often involves providing more appetizing food which has a greater nutrient density.

Providing peace and quiet to recuperate is also very important, especially if they are dealing with chemotherapy or radiotherapy treatments. This will help ensure the efficacy of treatment, as well as improve their quality of life.

Although there are ways we can support a dog with metastatic lung cancer, there is an almost nil chance of them changing its terminal nature. This means the disease will eventually reach the stage when the dog's quality of life is very low. In these cases, the most humane course of action will be euthanasia.

You can discover more about the treatment of fatal cancers with our article on fibrosarcoma in dogs.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Metastatic Lung Cancer in Dogs, we recommend you visit our Degenerative diseases category.