Symptoms of Lung Cancer in Dogs

Lung cancer is a condition that affects our beloved canine companions. Although lung tumors are rare in dogs, it is a complex and often devastating disease. It can strike any breed, age, gender or size of dog, and its causes remain multifaceted and not fully understood.

This illness primarily occurs when abnormal cells within the lungs grow uncontrollably, forming tumors or causing structural changes within the respiratory system. These tumors can either originate in the lungs themselves, commonly referred to as primary lung cancer, or spread from other parts of the body, resulting in metastatic lung cancer. The latter is more common.

Dogs exposed to secondhand smoke are at an increased risk of developing the disease. Although any dog can potentially be affected, certain breeds appear to be more prone to contracting the disease due to their genetic predisposition. Examples include Australian Shepherds, the West Highland White Terrier, Bernese Mountain Dogs, and the Bichon Frise.

Statistics show that over 50% of dogs over 10 years of age will develop cancer, but only 1% of these cases account for lung cancer. However, despite primary lung tumors in dogs being rare, more than 80% are cancerous when they do occur. Additionally, it is highly likely that these tumors will spread to the lymph nodes, chest cavity bones, and brain.

This article will explore the types of lung cancer in dogs, symptoms, diagnosis, treatment, stages, and life expectancy for dogs suffering from the disease.

Types of Lung Cancer in Dogs

Although less common in dogs than in humans, lung cancer is a serious and often fatal condition. There are several variations of this illness that can affect our four-legged friends, including:

Primary Lung Tumors

This refers to tumors that originate in the lungs and can be broadly categorized into two main types, namely, adenocarcinoma and squamous cell carcinoma. Adenocarcinomas tend to be slow-growing and are often detected at an advanced stage, whereas squamous cell carcinomas are more aggressive. Dogs with primary lung carcinomas may exhibit symptoms such as coughing, labored breathing, and lethargy.

Metastatic Lung Tumors

These are secondary tumors that have spread to the lungs from other parts of the body. Dogs may develop metastatic tumors as a result of cancer originating elsewhere, like the mammary glands or bone. The symptoms vary depending on the location of the primary tumor and include coughing, weight reduction, and respiratory distress.

Pulmonary Carcinomas

This term encompasses various types of lung cancer, including small-cell lung carcinoma and large-cell carcinoma. Small-cell carcinomas are highly aggressive, while large-cell carcinomas tend to grow more slowly. Both types can lead to symptoms such as coughing, chest pain, and difficulty breathing.

Pleural Mesothelioma

While relatively, pleural mesothelioma affects the lining around a dog's lung, also known as the pleura. It is often linked to asbestos exposure and can cause breathing difficulties, chest pain, and fluid accumulation in the chest cavity.

Causes of Lung Cancer in Dogs

The causes of lung cancer in dogs are not entirely understood, but several factors may contribute to its development. Below is a list of potential causes and risk factors associated with the disease:

1. Genetic Predisposition: Certain dog breeds appear to be more prone to lung cancer due to their genetic makeup. For example, the West Highland White Terrier, Bichon Frise, Australian Shepherd, Bernese Mountain Dogs, and Boxers have a higher risk of developing this disease.

2. Secondhand Smoking: Exposure to cigarette smoke is a significant risk factor for lung cancer in dogs, just as it is for humans. Therefore, dogs living in households with smokers are at an increased risk.

3. Environmental Toxins: Exposure to cancer-causing pollutants such as air pollution, asbestos, and other carcinogens may cause your dog to be more susceptible to contracting the disease.

4. Age: It is more common in older dogs, with the risk increasing as dogs age. This is likely due to the cumulative effects of long-term exposure to potential carcinogens.

5. Occupational Hazards: Dogs that work in environments with exposure to industrial chemicals or environmental toxins may have an increased risk of developing lung cancer.

6. Radiation Exposure: Dogs that have undergone radiation therapy for other medical conditions may have an increased risk of developing secondary cancers, including that of the lungs.

7. Diet and Nutrition: While not a direct cause, diet and nutrition can play a role in a dog's overall health and immune system function. A healthy diet and appropriate weight management can help support the immune system's ability to combat cancer.

Symptoms of Lung Cancer in Dogs

The symptoms can be subtle and easily mistaken for other respiratory issues. Consequently, you must be vigilant about changes in your dog's health. Common clinical signs that your furry friend may have a lung tumor include:

• Coughing: Persistent and unproductive coughing is one of the earliest symptoms of lung cancer. The cough may be dry or accompanied by blood.

• Labored Breathing: Dogs with a lung condition may experience increased respiratory rate and effort. They may also show signs of wheezing and shallow breathing.

• Reduced Exercise Tolerance: If your dog becomes less active, struggles during exercise, or tires easily, it could be one of the early signs of lung cancer.

• Weight Loss: Unexplained weight loss, even when appetite remains normal, is a concerning symptom.

• Lethargy: A general lack of energy, reluctance to engage in activities, and a change in behavior could be indicative of illness.

• Loss of Appetite: Dogs with the disease may lose their appetite, leading to reduced food consumption.

• Hemoptysis: Coughing up blood can be a severe symptom and requires immediate medical attention.

• Cyanosis: In advanced cases, dogs may develop a bluish tint to their mucous membranes such as the gums and tongue due to decreased oxygen levels in the blood.

Note that both primary lung cancer and metastatic cancer in dogs have similar symptoms, but coughing in the former is typically more common than in the latter.

Diagnosis of Lung Cancer in Dogs

If you notice any of the aforementioned symptoms in your dog, it is crucial to consult a veterinarian promptly. Diagnosing this ailment typically involves a combination of the following steps:

• Physical Examination: Your veterinarian will conduct a thorough physical examination, paying particular attention to your dog's respiratory system and chest.

• Radiographs (X-rays): Chest X-rays are the primary imaging tool used to detect lung cancer. They can reveal the size, location, and extent of the tumor.

• Cytology: A fine needle aspiration biopsy may be performed to obtain a sample of the tumor for cytological analysis. This helps determine the type of cancer and its malignancy.

• Blood Tests: Bloodwork provides insights into the dog's overall health and may detect any secondary complications related to the cancer.

• Computed Tomography (CT) Scan: In some cases, your veterinarian may recommend a CT scan, which is used for more detailed imaging to assess the extent of the cancer and help with treatment planning.

Treatment of Lung Cancer in Dogs

Once your furry friend has been diagnosed with this illness, the next logical step is treatment. However, the choice of treatment is made depending on the size of the tumor, the type of cancer, its stage, the dog's overall health, and the owner's preferences. The most common treatment options include:

Thoracic Surgery: If the tumor is localized, surgery may be an option for removing it. However, this is typically more common in cases of a primary lung tumor and is often accompanied by chemotherapy. Thankfully, most dogs tend to improve drastically after surgery.

Chemotherapy: Chemotherapy is commonly used for treating cases where the cancer has spread. It helps slow down the progression of the disease, alleviate symptoms, and improve the dog's quality of life.

Radiation Therapy: Radiation therapy may be used to treat cancer in dogs, especially when surgery is not an option. It is also often combined with chemotherapy for more effective results.

Palliative Care: When multiple tumors are found and the cancer is too advanced for curative treatment, palliative care focuses on managing symptoms and improving the dog's quality of life through therapy and medication.

Stages of Lung Cancer in Dogs

Staging helps determine the extent of the disease and plays a crucial role in treatment decisions. The stages are typically classified as follows:

Stage 0: The cancer is limited to a portion of the lung and has not spread.

Stage 1: The tumor is localized within the lung and has not spread to the dog's lymph nodes.

Stage 2: The tumor has invaded nearby structures or has spread to regional lymph nodes.

Stage 3: The cancer has spread more extensively within the chest or has invaded other organs within the chest.

Stage 4: The cancer has metastasized to distant organs, making it difficult to treat.

Life Expectancy for Dogs with Lung Cancer

The outlook for dogs diagnosed with this fatal disease is subject to variability, influenced by factors like the cancer's type, its stage, the location of the tumor, the dog's overall health, and the selected treatment plan. Dogs in the early stages, when managed with appropriate treatments, may witness an extension in their average survival time, potentially spanning over a year or more.

Conversely, in cases where the cancer has progressed significantly or has metastasized to other areas, the prognosis tends to be less optimistic with a life expectancy of about two months. In such advanced instances, the emphasis shifts to palliative care, prioritizing the dog's comfort and general quality of life.

Palliative Care

Dealing with a diagnosis of lung cancer in your beloved canine companion can be an emotionally challenging experience. When the illness is advanced, aggressive treatments may not offer a cure or significant improvement, and in such cases, palliative care becomes a crucial consideration. Here are some key aspects of palliative care:

1. Pain Management: Lung cancer can cause discomfort and pain. Palliative care prioritizes pain management through the use of medications, such as non-steroidal anti-inflammatory drugs (NSAIDs) and opioids, to ensure that your dog is as pain-free as possible.

2. Symptom Control: Your dog may experience a range of distressing symptoms, including coughing, labored breathing, and loss of appetite. Palliative care aims to alleviate these symptoms, improving your dog's quality of life. Medications and therapies may be administered to ease these distressing signs.

3. Nutrition Support: Dogs with this ailment tend to lose their appetite, making it challenging to maintain a healthy body weight. Palliative care includes dietary adjustments, such as providing highly palatable and nutrient-dense foods, to ensure your dog receives essential nutrients and stays well-nourished.

4. Emotional Support: Caring for a dog with cancer can take an emotional toll on both the pet and the owner. Palliative care considers the psychological and emotional well-being of both, providing support and counseling when needed.

5. Hospice Care: In some cases, dogs with advanced lung cancer may benefit from hospice care. This approach focuses on end-of-life comfort and allows your dog to remain at home surrounded by familiar and loving faces. It includes providing pain relief, supportive care, and ensuring a peaceful and dignified end.

The Bottom Line

Lung cancer in dogs refers to the development of abnormal cells in the lungs of a canine. These cells divide and multiply uncontrollably, forming tumors or leading to structural changes within the respiratory system. It can occur in dogs of all breeds, ages, genders, and sizes.

This disease is categorized into two main types: primary lung cancer, where the disease originates in the lungs, and metastatic lung cancer, where it has spread to the lungs from another part of the body. Although any dog can contract this illness, particular breeds seem to be more susceptible, including Boxers and Australian Shepherds. In addition, older dogs of 10-12 years of age tend to be more affected.

Lung cancer in dogs is a complex condition with various causes, types, symptoms, diagnostic methods, treatment options, stages, and life expectancy. Early detection and timely intervention are critical for improving the chances of a favorable outcome.

If you suspect that your dog may be ailing from this disease, consult your veterinarian immediately for a thorough evaluation and a tailored treatment plan.

References

1. Merck & Co. (2018, June). Cancers and Tumors of the Lung and Airway in Dogs. Merck Veterinary Manual. Retrieved from https://www.msdvetmanual.com/dog-owners/lung-and-airway-disorders-of-dogs/cancers-and-tumors-of-the-lung-and-airway-in-dogs

2. Animal Hospital of Clemmons. (2021, January 29). Lung Cancer in Dogs: Symptoms and Treatments. Veterinary Pet Care Blog. Retrieved from https://www.animalhospitalofclemmons.com/site/veterinary-pet-care-blog/2021/01/29/lung-cancer-in-dogs-symptoms-and-treatments#:~:text=While%20primary%20lung%20tumors%20are,chest%20cavity%2C%20bones%20and%20brain

3. Eastcott Referrals. (n.d.). Lung Tumours. Fact Sheets for Pet Owners. Retrieved from https://www.eastcottreferrals.co.uk/pet-owners/fact-sheets/lung-tumours/