Lung cancer in dogs may occur due to a tumor that starts in the lungs or one that spreads to the lungs from a different location. But either way, it can be a scary-sounding diagnosis. To help you know what to expect, integrative veterinarian Dr. Julie Buzby explains the causes, symptoms, diagnosis, treatment, and prognosis for lung cancer in dogs.
Compared to many other types of cancer, primary lung tumors (i.e. cancer that starts in the lungs) are rare in dogs, accounting for only 1% of cases of cancer in dogs. However, over the last 20 years or so, it seems that the number of lung cancer cases in dogs are rising.
Understandably, this is concerning for veterinarians and dog parents alike. While the exact reason for this change isn’t fully understood, it is good for dog parents to have the facts.
What is lung cancer in dogs?
Lung cancer in dogs occurs when abnormal cells replicate and form a tumor. This mass can destroy normal lung tissue and potentially spread to other locations. Sometimes the tumor originates in the lungs. This is called primary lung cancer. But in other cases, a tumor spreads to the lungs from elsewhere in the body. This is known as secondary lung cancer, and it is the far more common type of lung cancer in dogs.
Primary lung cancer in dogs
Unfortunately, about 80% of primary lung tumors in dogs are malignant (i.e. cancerous). Primary lung cancer starts out as a solitary mass affecting one lung lobe, but can invade other lobes. And it can spread to other parts of the body, including the lymph nodes, liver, kidneys, pancreas, chest cavity, bones, and brain.
The vast majority of all primary lung tumors in dogs are carcinomas, with the two most common types being adenocarcinomas (e.g. papillary or bronchogenic adenocarcinoma) or alveolar carcinomas (e.g. bronchioalveolar carcinoma). However, dogs can also have other primary lung tumors, including squamous cell carcinoma, osteosarcoma in dogs, mast cell tumor in dogs, histiocytic sarcoma, and anaplastic carcinoma.
Secondary lung cancer in dogs
On the other hand, cancer in a different area of the body can spread (i.e. metastasize) to the lungs, creating secondary lung tumors. Often, vets will refer to this as metastatic lung disease or metastatic lung cancer.
The lungs are one of the most common organs to be affected by metastasis. This is the case because your dog’s entire blood volume moves through the lungs. Thus, cancer cells that make it into the blood stream can easily go to the lungs, lodge there, and start creating lung tumors. Sometimes the dog may only have one tumor or a few tumors. But in other cases, there will be many tumors spread throughout the lung lobes.
Many common types of cancer spread to the lungs, including:
- Hemangiosarcoma in dogs
- Osteosarcoma
- Mammary cancer
- Bladder cancer in dogs
- Mouth cancer in dogs
- Liver cancer in dogs
- Prostate cancer in dogs
Lung masses that aren’t cancerous
Additionally, there are some lung problems that can look like lung cancer or have similar symptoms to lung cancer, but are actually due to a non-cancerous process. For example, sometimes focal masses in the lung can be due to infections like pneumonia in dogs or an abscess. Or a dog with fungal lung disease may have multiple spots in the lungs that look like metastatic lung cancer but aren’t.
How do dogs get lung cancer?
Cancer is more likely to happen in senior dogs, with an average age of 10 to 11 years. Like in humans, older dogs are at a higher risk due to the accumulation of cellular damage over time. Still, lung cancer can affect dogs of any age. All breeds can develop lung cancer, though Bernese Mountain Dogs, Boxers, Dobermans, and Irish Setters may have a slightly higher risk.
There is a known link between environmental tobacco smoke and lung cancer in people. But secondhand smoke has not been definitively proven to cause primary lung cancer in dogs. Even still, experts recommend avoiding exposing your pets to it. Research does suggest, though, that dogs exposed to air pollutants and to radon may have a higher risk of developing primary lung tumors.
What are the symptoms of lung cancer in dogs?
Should a dog develop lung cancer, the symptoms can be variable. Interestingly enough, one in four dogs with primary lung tumors will be asymptomatic at the time of diagnosis. (Those tumors may be found on imaging performed for other purposes.) However, dogs may also show some of the following signs of lung cancer:
- Dog coughing and gagging—Over 95% of dogs who are symptomatic will be coughing
- Lack of appetite
- Being a lethargic dog
- Weight loss
- Coughing up blood
- Difficulty breathing or abnormal sound to the breathing
- Dog breathing fast
- Difficulty exercising
- Vomiting or regurgitation
- Difficulty swallowing
Additionally, if the dog has metastatic lung tumors, you may see clinical signs related to the original tumor. These symptoms could include bleeding into the abdomen, difficulty urinating, limping, or masses on the skin, mammary glands, or mouth.
How does the vet diagnose lung cancer in dogs?
If your vet suspects your dog may have lung cancer, he or she may start with performing a physical exam and gathering a history. Then he or she will discuss any recommended diagnostic tests.
X-rays
Chest X-rays are often the primary way your family veterinarian will find a lung tumor. But X-rays cannot determine what type of lung tumor it is. Also, a tumor must be at least 5 millimeters in size to show up on an X-ray. This is important to understand because 40% of dogs with metastatic lung cancer have tumors that are too small to be visible on an X-ray.
CT scan
A CT scan is the gold standard for detecting lung cancer. This is the case because it is the least likely to miss a tumor and can detect smaller nodules than X-ray. Additionally, it can help the vet determine if the tumor has invaded any surrounding tissue. However, you would need to go to a veterinary specialist near you for a CT as they are not typically available in a general practice setting.
Ultrasound
In some situations, the vet may recommend a lung or abdominal ultrasound. Lung tumors do show up on ultrasound. But an ultrasound can only evaluate the periphery of the lungs, so it can miss tumors that are deeper in the lungs.
Abdominal ultrasound is useful for looking for tumor spread or searching for the primary tumor.
Cytology or biopsy
In order to attempt to determine the type of lung tumor, the vet (or veterinary pathologist) will need to examine the tumor cells under a microscope. Sometimes, if the tumor is close to the chest wall, the vet can perform an ultrasound guided aspirate or biopsy (i.e. use a needle to get cells or tissue from the tumor). However, this method may provide a non-diagnostic sample.
Therefore, a traditional biopsy (i.e. examining sections of the tumor under the microscope after the tumor has been removed) is the best way to determine the tumor type, grade, and stage. Plus, it allows the veterinary pathologist to assess if the vet removed the whole tumor.
Additional diagnostics
The vet may also recommend blood tests for dogs, urinalysis, a dog lymph node aspirate (i.e. looking at lymph node cells under the microscope) or other tests. These diagnostics allow the vet to look for tumor spread, rule out other problems, or make a treatment plan.
What are the stages of lung cancer in dogs?
Based in the diagnostic information the vet gathers, he or she may apply a staging system to a primary lung tumor. One potential staging system, based on the World Health Organization system is:
- Stage I—Small primary lung tumor that has not spread elsewhere
- Stage II—Tumor is larger and has spread to the lymph nodes nearby
- Stage III—Cancer has spread to the lymph nodes in the mediastinum (i.e. area between the lungs)
- Stage IV—Lung cancer has spread to the brain, kidneys, liver, or other organs
However, a new staging system for lung tumors in dogs has also been proposed. It is called the canine lung carcinoma stage classification (CLCSC). It’s based off the human lung cancer stage classification (HLCSC). CLCSC subdivides the tumors based on size since tumor size can be a prognostic indicator. The categories in that system are: less than or equal to three centimeters, between three and five centimeters, between five and seven centimeters, and greater than seven centimeters.
What is the treatment for dog lung cancer?
The treatment for lung cancer in dogs can vary depending on type and stage of the tumor, and whether it has metastasized.
Surgical lung lobectomy
If there is no evidence the tumor has metastasized, the treatment of choice is to have the affected lung lobe surgically removed (i.e. lung lobectomy). In most cases, this involves open-chest surgery (vs. a laparoscopic procedure).
However, if the surgeon discovers enlarged lymph nodes or a surgical lymph node biopsy indicates the tumor had actually spread, the dog may need follow-up chemotherapy or radiation.
Chemotherapy
If there are signs of metastasis, surgery isn’t a good option, or not all of the tumor was removed, chemotherapy can also be used to treat lung tumors. Your veterinary oncologist can help find the chemotherapy protocol that is right for your dog.
Radiation
Occasionally, the veterinary oncologist may recommend stereotactic body radiation therapy (SBRT) to try to precisely target the lung tumor. Or he or she may use hypofractionated radiation therapy to provide palliative care.
Supportive care
Regardless of the type of cancer present, your veterinarian may prescribe medications to help your dog feel better. They include:
- Antibiotics—If there is evidence of a secondary bacterial infection in the lungs, antibiotics can be helpful.
- Anti-inflammatory medications—These medications will help improve local inflammation around the cancer and decrease discomfort.
- Cough suppressants—Certain pain medications can also help reduce cough, keeping dogs more comfortable.
- Bronchodilators—These medications can help open the tiny lower airways in the lungs.
Additionally, you can help support your dog by keeping a cool ambient temperature in the house and paying close attention to the temperature and humidity when taking your dog outside. Heat and high humidity can make it harder for your dog to breathe. You should also avoid exposing your dog to air fresheners, perfumes, smoke, or other irritants.
Palliative care
If treatment is no longer working or if you decide surgery, chemotherapy, or radiation aren’t right for your dog, you may switch your focus to palliative (i.e. comfort) care. What exactly this entails will depend in your dog’s situation.
If your dog has fluid building up around the lungs due to the tumor, therapeutic thoracocentesis (i.e. using a needle to remove the fluid from the chest) can help your dog breathe better. Or if your dog is painful due to tumor spread, your vet may recommend a combination of different pain medications to give your dog some relief.
If you have concerns about your dog’s comfort, please talk to your vet. He or she can work with you to find some solutions that might help your dog.
What is the prognosis and life expectancy for dogs with lung cancer?
The outlook for dogs with primary lung cancer can be variable. If the dog has a primary lung tumor that has not spread, he or she may survive for around 12 to 16 months, or sometimes even longer, after a lung lobectomy. But without treatment, or with more advanced lung cancer, average survival times may only be around two to three months.
Overall, the prognostic indicators for primary lung tumors include:
- Lymph node spread—Prognosis is better if the tumor has not spread to the lymph nodes.
- Tumor grade—Lower grade tumors have a better prognosis than higher grade tumors.
- Tumor size—Smaller tumors carry a better prognosis.
- Symptoms—Dogs who were asymptomatic at the time of diagnosis generally lived longer.
- Tumor stage—Lower stage is more favorable.
- Tumor type—The prognosis is better for papillary adenocarcinoma than other primary tumor types.
Since there is so much variation, your veterinarian or veterinary oncologist can give you a better idea of what to expect for your dog.
Additionally, your vet can help you understand the outlook if your dog has metastatic lung cancer. With all the different types of cancer that can spread to the lungs, it isn’t possible to give a specific idea of life expectancy here. However, in general, once a tumor has spread to the lungs, the overall prognosis tends to be poor.
How do you know when to put down a dog with lung cancer?
Unfortunately, the day may come when you have to start considering if it is time to euthanize your dog with lung cancer. In end-stage lung cancer, your dog may have significant trouble breathing, be coughing frequently, not be able to eat well, be in pain, or have minimal energy. And his or her quality of life may decline as a result. In that situation, the kindest thing may be to set your beloved dog free from his or her struggles.
Lean on your support network and spend time with your dog
I know that hearing the word “cancer” can be scary. And lung cancer is no different. If your dog has been diagnosed with lung cancer, or lung cancer is on the table as a potential diagnosis, the best advice I can give you is to cling to your support system and to remember that you still have today with your dog.
Your veterinarian or veterinary oncologist can provide a wealth of medical information. But they can also give you emotional support and guidance for the journey. And your family and friends are there for you too. You don’t have to face this alone—and you shouldn’t.
Additionally, I urge you to pause your research for a moment, go sit with your dog, and enjoy just being with him or her. It is tempting to want to read and read about your dog’s condition, and I fully support that. But it is also important to stop for a moment and have some quality time with your dog. This can be a comfort to you, and to your dog too.
Was your dog diagnosed with a lung cancer?
Please share his or her story below.
My 9 year old black Labradoodle, Gunner, has always been a big guy. All his adult life he has weighed in at about 100 lbs (not overweight, he is just big, stout). He has been dropping weight over the past year and going grey. I assumed it was just the typical aging issues. About a year ago he started coughing here and there. I have taken him to the vet several times for it, and they have assumed it was kennel cough as he does attend doggie daycare throughout the week. A couple weeks ago the coughing had gotten persistent and he seemed to be having a hard time breathing. I took him in again, he was running a slight fever but his heart and lungs sounded good so they prescribed him antibiotics and steroids. After the meds were finished he was no better. Took him in again and this time he was down a total of 20 lbs. since last fall and the vet felt a lump in his neck/throat. We thought he may have gotten something stuck in his throat so they took an X-ray. They found a large tumor pushing up against his windpipe causing it to bend. Upon further inspection, and X-rays of his chest, they found that his lungs and chest cavity were overrun with cancer. The news was shocking and devastating to say the least. The vet told me he probably had days to weeks to live before his quality of live deteriorated to the point he would be in too much distress, therefore we would need to make the call to let him go. It has been 2 weeks now. He’s continued to take prednisone twice a day to help with the inflammation of his airway. Within that time, he has stopped eating his dog food, however will still eat human snacks and dog snacks. I have started preparing him chicken and rice, which he will happily eat. There are times he just looks so sad and exhausted and I think it’s time to make the call. But then there are still moments that he looks happy and still able to enjoys life. I don’t want him to suffer but I also don’t want to make the decision prematurely. He really struggles with breathing and it’s very labored even during sleep and rest. We are keeping him inactive (not that he gets excited anymore about much). I am thinking that he doesn’t have but just a few days left and it’s very depressing.
Dear Stephanie,
My heart goes out to you as you spend these final days with Gunner. I hope you can find a way to fill this time with joy and love. Praying for your strength and comfort as you navigate this emotional path. Bless you and your sweet boy. ♥
Our lovely Dollar, an 11 year old labrador retriever, just got diagnosed today. We were advised to prepare the the forth coming weeks as she will be declining soon. She was started on Prednisone to help with her labored breathing. Right now, our priority is spending more time with her and making sure she enjoys every bit of time she has left. I am still hurt and extremely sad and unsure of how to cope but I will dedicate every time I have to care for her.
Dear Lora,
I am sorry Dollar has received this tragic diagnosis and you are facing these final days with her. I am glad you are trying to make the most of the time you have and finding ways to bring joy to each day. Here is a link to another article that may be very helpful during this time: Preparing for Your Dog’s Euthanasia: 10 Thoughts for Peace
Wishing you all comfort and peace. Bless you and your sweet girl. ♥
I am going through the same thing right now with my 15 year old cocker.
I feel your pain.
I’m so sorry 😞 I too am facing the same with my rescue cocker and he’s 13-15
Sending prayers 🙏
My baby daughter Toffee is leaving me behind and has entrusted me to facilitate her passage. She is 9 years and 4 months old and truly an angel. People might think I am a master dog trainer, but in reality, I did nothing; she was just super polite and incredibly smart. In December 2023, I found a lump on her that turned out to be a mammary tumor. It was successfully removed, and Toffee fully recovered as I relentlessly watched over her and cared for her. As soon as the vet confirmed she was healed, I fell apart and became ill with medically unexplained reasons that persist to this day. This illness caused me to lose my job and my life outside the home, allowing me to stay with Toffee 24/7 from December 2023 until now, August 26, 2024. Ironically, as I started to get better recently, Toffee began showing symptoms of GERD. On August 2nd, we went to the vet for an X-ray of her esophagus, which revealed tumors all over her lungs. Her health deteriorated rapidly, and by August 24th, we barely made it to the vet and back home. The X-ray confirmed the extent of the tumors, and the vet told me I would need to let her go in a matter of days. This is the worst I have ever felt in my life, even worse than recovering from heroin addiction and rebuilding my life—a life that now lacks purpose. It is so unfair that I have to continue living, but I hope that what remains of me is what I learned from her and that I can pass it on to any other innocent creature in need. (I took Toffee from my manager, who had put her up for adoption, to bring her to a friend of mine who then refused to take her because she is a Labrador mix, not purebred. Before I could return her, I got food poisoning and stayed in bed for a few days, and she never left my side. We’ve been together since then—what an unplanned magical journey that sadly has to end)
Dear Toffee’s father,
My heart goes out to you as you grieve the loss of your beloved girl. What a blessing you found each other and it brought out the best in you both. It is clear Toffee was dearly loved and I am certain she knew how much she meant to you. I know it will be hard without her by your side, but I hope you will be comforted knowing you gave her the peace and rest she deserved. I cannot think of a greater act of selfless love than to allow your own heart to break so that your girl didn’t have to suffer needlessly. May her memory stay with you always as you continue life’s journey. Praying for healing for your heart and wishing you brighter days ahead. ♥
My 15 year old Westie was just diagnosed with pulmonary lung cancer. The Xrays showed a mass that was about 7CM on his right lower lung. It was devastating and heartbreaking as aside from coughs which just seemed to happen suddenly, he is totally fine. It is just sad to know that the inevitable is approaching,
We are opting to skip surgery after speaking with the surgeon. It would take him 2-3 months to heal (provided it is a success through the open chest surgery and anesthesia), and the prognosis can’t be determined.
At this point, the best quality of life with the limited time he has left is our primary objective.
So we are showering him with walks, car rides, lots of yummy snacks and hugs.
Dear Regina,
My heart goes out to you as you face these last days with your beloved Westie. I think it is great you are trying to make the most of the time you are gifted and showering your pup with love and affection. Praying for your strength and comfort as you walk this emotional path. Bless you and your sweet boy.
My 9-year-old boxer went to a cardiologist for an assessment of arrhythmia. The imaging for his heart revealed a 5.4×5.2 cm mass in the right caudal lung field. At this point, he is not showing any symptoms of distress. We have not yet stabilized his arrhythmia, so there are no options to explore the source or type of the mass. I am most concerned with maintaining his quality of life so, even with options for surgery or treatments that are disruptive to his comfort, I do not think I would take them.
He eats and drinks fine and maintains a lower but involved activity level. I do no know how long he will sustain this, but I enjoy each day with him.
Dear Grace,
I am sorry your Boxer is facing this difficult situation. I understand your concern and also think it is good you are focused on his comfort and quality of life. Try to make the most of the time you are gifted. Praying for clarity and peace as you navigate this unknown path.
My dog was recently diagnosed with metastatic lung cancer. The primary tumor is a hemangiosarcoma tumor in the right atrium of her heart. The symptoms we noticed seemed sudden and are from the lung cancer. we are trying to support her and spoil and love her until it’s time to let her go. We are going to start prednisone tomorrow as her breathing is getting more labored and her cough is worse. Thank you for your article.
Dear Lyllian,
I am sorry your girl has received this devastating diagnosis and is facing her last days. Try to make the most of the time you are gifted and lavish her with love and affection. Praying for your strength and comfort as you navigate this emotional path. Bless you and your sweet girl. ♥
I am going through the same thing right now with my 15 year old cocker.
I feel your pain.
Dear Diane,
My thoughts are with you as you face this difficult situation with your senior pup. Bless you. ♥
Hi there. I am curious- how is prednisone helping your pup? Mine is currently on Vetprofen and I am not sure when do we ask for stronger meds. He seems absolutely fine now, though his prognosis isn’t good.
I had a beagle Jack mix I adopted in 2020. In 2021 I took her to the ER because she seemed bloated and not eating. The vet x rayed her and on the film she saw a tennis ball size mass on the right side of her chest. She recovered just fine but I did take her to AVIM&O for biopsy and possible treatment. Diagnosed with bronchial carcinoma I elected Piroxicam instead of sx due to possibility for recurrence. She liv d 2 1/2 more years! Had a happy life. Saw her Vet every month for rads and bloodwk. This year more tumors appeared and on June 10 we thought it best to say good bye and not let her struggle anymore. I also had her on supplements ( turkey tail mushrooms etc) raw diet and long walks as she tolerated. What is belly breathing and why? We experienced this toward the end. Thank you so much.
Dear Rita,
I am sorry for the loss of your senior girl to this terrible disease. What a blessing you gained over 2 extra years together and were able to offer her a peaceful passing. Belly breathing is when a dog’s oxygen levels are too low, and they are struggling to get enough air into their lungs. In order to try and take in more air with each breath, they will use their abdominal muscles to try and pull the diaphragm (main muscle that is in charge of breathing) down to take a bigger breath. It makes them look like their stomach is heaving when they breathe. Thank you for sharing your story with us and bringing up this important topic. I am sure this will help others as they face a similar situation. Wishing you all the best as you continue life’s journey. Bless you.
Yes, my 11 yr old Jack Russell was suddenly diagnosed after a bout of bronchitis. It was horrible and so sudden. He was in terrible pain. My dog had Addisons disease and was on steroids since the age of 4, this was the reason he was so susceptible to this horrible disease
Dear Patty,
My heart goes out to you as you face this difficult diagnosis in your senior boy. I pray the veterinary team will find the best way to ensure he remains happy and comfortable for as long as possible. Wishing you strength and peace as you navigate the unknown path ahead.
My 11 year old Jack russell has been diagnosed with lung cancer today after 4 weeks of ‘kennel cough’ and has been placed on palliative care. He must have been in so much pain and still wagged his tail every day. We are in so much shock thinking he had years left and now he’s lucky to have a couple of months.
Dear Rosie,
My heart goes out to you as you face this emotional situation with your senior guy. Make the most of the time you are gifted and fill each day with happiness and joy. Praying for comfort and peace for everyone involved. Bless you and your sweet boy. ♥
We have a beautiful Springer Spaniel Eva. She will turn 16 in 3 months. She spent a week at a kennel, as we went on our first vacation in years. Returning we thought she had kennel cough. Our Vet diagnosed her with a lung tumor. She thought at her age, she may live 2-4 weeks. We have been back 2 weeks and her breathing is very labored. She’s barking loudly and is very restless. We walk at least 4,times a day.. Our hearts are torn we have planned a 3-4 week trip to Italy for our 35th wedding anniversary. We felt we should cancel but decided , she was getting more stressed each day.. We FaceTimed with our kids today .. I’ve cried a river the last week. Tomorrow we say our goodbyes.. Miss Eva is the only dog our family has ever had, my first dog also. She will always be in our hearts and never forgotten. I’m going to miss her so much..
Dear Sharon,
My heart goes out to you with your recent loss of Eva. I can only imagine how much you miss her but what a blessing you were able to offer her a peaceful goodbye and spare her from unnecessary suffering. May her memory be with you and your family forever. Wishing you comfort and brighter days ahead.