Lung Cancer in Cats

What Is Lung Cancer in Cats?

Cancer in cats is a concerning diagnosis—and lung cancer is especially alarming. But understanding your pet’s condition can help.

Lung cancer in cats is when tumors, or masses of cancerous cells, develop in the lungs. Lung cancer is clinically called pulmonary (relating to or affecting the lungs) neoplasia (uncontrolled abnormal cell growth).

Lung cancer can be primary or secondary. Primary lung tumors start in the lungs. Secondary, or metastatic, lung tumors start in another part of the body and spread to the lungs.

Lung tumors damage the lungs and affect their ability to move oxygen into and carbon dioxide out of the bloodstream. Tumors may also squeeze the lungs or allow fluid to accumulate around the lungs, making it more difficult for your cat to breathe.

Primary lung cancer in cats is rare. Of 5,643 cat cancer cases presented to the North Carolina State University Veterinary Teaching Hospital for evaluation, only 39 (0.69%) were primary lung tumors (pulmonary carcinomas).

However, primary lung cancer is diagnosed more often than it was 20 years ago. This could be due to better detection methods, an increase in exposure to environmental carcinogens (tobacco smoke, radon, and other types of pollution), and cats living longer lives.

On the other hand, the lungs are a common organ for cancer to metastasize to from other parts of the body, so secondary lung tumors are more prevalent than primary.

Primary lung tumors have a better prognosis, but survival rates are affected by many factors, including tumor type, severity, and when the cancer was first diagnosed. Secondary lung tumors typically have a poor prognosis because cancer is already present in other parts of the body.

Types of Lung Cancer in Cats

A study that investigated the different types of primary lung tumors in cats found three main types of cancer:

• Pulmonary adenocarcinoma—Pulmonary adenocarcinoma is a cancerous tumor that usually develops from the glands that line the bronchi (airways within the lungs). 82% of primary lung tumors in cats were pulmonary adenocarcinomas.

• Bronchogenic carcinomas—Tumors arising from other tissues within the bronchi were responsible for another 11% of primary lung tumors.

• Squamous cell carcinoma—The remaining 7% of tumors involved two types of squamous cell carcinomas, which arise from the outermost layer of the epithelial tissue (the squamous epithelium) that lines airways.

There are many different types of secondary lung tumors in cats. Cancer of almost every sort that is located virtually anywhere in the body can metastasize to the lungs.

Symptoms of Lung Cancer in Cats

Signs of all types of lung cancer in cats can include:

• Difficulty breathing

• Rapid breathing (more than 40 breaths per minute)

• Loud breathing

• Weight loss

• Lethargy

• Coughing that may contain blood

• Vomiting or diarrhea

• Lameness due to lung digit syndrome (tumors spreading to one or more of the toes)

Causes of Lung Cancer in Cats

Few cancers have a single known cause. Lung cancer risk is likely dependent on environmental, genetic, and other factors.

Males and females appear to be equally affected, but older cats are more likely to be diagnosed with lung cancer.

Research on 39 cats found that Persians were four times more likely than any other breed to develop lung cancer. Exposure to cigarette smoke has been linked to lung tumors in pets and may increase the chance that a cat will develop the disease.

How Veterinarians Diagnose Lung Cancer in Cats

Your veterinarian will initially perform a complete physical examination, including listening to your cat’s heart and lungs with a stethoscope. Blood work and urinalysis will probably be recommended to evaluate your cat’s internal organs.

Chest X-rays are often the first step in identifying tumor presence. Staging (searching for spread to other body locations) is usually recommended as well.

A CT scan or MRI can help the vet better visualize lung tumors. CT scans can reveal a tumor’s exact location, how invasive it is, and any potential spread to other parts of the body.

If there is still uncertainty in a diagnosis, your cat’s veterinarian may perform a fine needle aspirate, where a small needle is used to take a sample of the tumor cells and view them under a microscope. A tissue biopsy is more invasive and involves taking a piece of the tumor for analysis. This method can most definitively diagnose lung cancer in cats.

To provide the most accurate information to your veterinarian—and to ensure you don’t forget anything—write down your cat’s symptoms as you observe them prior to your veterinary visit.

Your cat’s veterinarian likely has records of previous care, but you may want to check that all prior history, including anything involving tumors, is accounted for.

Treatment of Lung Cancer in Cats

If cancer is diagnosed, your cat’s vet may refer you to a veterinary oncologist who can help you decide the best treatment plan moving forward. Your options will depend on the size, location, and stage of your cat’s cancer and your cat’s overall health.

Surgery to remove the portion of the lung with the tumor, or the entire lung itself, may be recommended for single tumors that are slow-growing. Tumors that cannot be removed may be treated with chemotherapy or radiation.

Radiation can help slow the growth of primary tumors. Chemotherapy is more likely to be recommended if the cancer has spread.

If treatment is not possible, palliative care (symptom relief) is the next best option.

Palliative care may include:

• Pain medication

• Fluid therapy

• Nutritional support

• Cough suppressants

• Anti-inflammatory medications (including corticosteroids such as prednisolone and dexamethasone)

• Antibiotics (to fight secondary infections)

• Thoracocentesis (to help remove fluid build-up around the lungs)

Recovery and Management of Lung Cancer in Cats

Radiation therapy may inflame lung tissue and have a sunburn-like effect on the skin. Chemotherapy can also have side effects, such as nausea, vomiting, and fatigue.

Cats who receive surgery may require intensive care, such as oxygen therapy, before being released. Once home from surgery, there are several ways you can support your cat’s care:

• Keep them in a quiet confined space for at least two weeks.

• Be attentive to their breathing.

• Limit their exposure to anything that could irritate their lungs, like secondhand smoke and other air pollutants.

• Make follow-up vet appointments.

• Follow aftercare instructions and give medication as prescribed.

Recovery times vary. Post-op recovery times are typically shorter for thoracoscopic procedures (a small camera is placed into the chest and incisions made with instruments) than thoracotomy procedures (traditional open chest surgery).

Your vet will instruct you on the best items for recovery after treatment. These may include:

• Surgical recovery body suit

• Recovery cone

• Soft collar

• Pet pen

• Waterproof blanket

Prevention of Lung Cancer in Cats

To promote your cat’s health and reduce lung cancer risk:

• Routinely take your cat to the vet to help catch cancer early.

• Reduce your cat’s exposure to environmental carcinogens, such as cigarette smoke.

• Consider running an indoor air purifier if you live in an urban environment. The link between city living and lung cancer in cats is not well-established, but cities are known to have higher amounts of air pollution, which may contribute to tumor development.