Lung Cancer in Cats

There are two types of lung cancer that affect cats: primary lung tumors and metastatic lung tumors. Primary lung tumors, which originate in the lung, are rare in cats. The number of cases of primary lung tumors in cats has increased in recent years, however, though the exact reason for the increase is unknown. Metastatic lung tumors are a secondary type of lung cancer that originally forms in another part of the body and spread to the lungs. Both types of lung cancer primarily affect cats that are older.

The symptoms of lung cancer may differ depending on where the cancer originated, how aggressive it is, and whether or not the affected cat has suffered from prior lung disease. Symptoms may manifest in different ways, and some may not appear at all. For example, breathing problems and coughing are surprisingly uncommon; less than a third of cats diagnosed with lung cancer have breathing problems.

Look out for any of the following symptoms if you suspect your cat may have lung cancer:

• Anorexia, or loss of appetite
• Lethargy and weakness
• Labored or rapid breathing
• Excessive coughing
• Coughing up blood
• Excessive hiding
• Fever
• Excessive meowing
• Insomnia
• Vomiting
• Sudden lameness

Metastatic cancer that has spread to the lungs may be accompanied by other symptoms depending on where the cancer originated, including:

• Change in urination and defecation
• Slow-healing wounds
• Skin sores
• Unexplained bleeding

The causes of lung cancer may vary depending on whether or not the cancer is primary or metastatic. However, the primary cause of lung, and many other types of cancer, is exposure to carcinogenic substances in the environment. Cats that live in households with an active smoker are twice as likely to develop cancer as those that live in smoke-free households.

The vet will initially perform a chest x-ray, but sometimes these can come back normal even if the cat does have cancer because tumors have to grow to a certain size before they are visible on x-rays. Ultrasounds and CT scans, used in conjunction with fine needle aspiration (FNA), are also diagnostic methods to diagnose several types of cancer. The vet may also take urine and blood samples in order to test for other diseases.

Before recommending a course of treatment, the vet will have to determine the stage of the cancer. Due to the nature of the cancer, treatment is purely palliative in many cases, or given to ease the cat’s pain as opposed to treating the underlying cause. 

For primary lung tumors, surgery is generally required to remove the part of the lung where the tumor is located. The extent of the surgery and supportive care needed will vary, depending on the location and size of tumor.  The surgery will normally be followed by chemotherapy or radiation treatment to slow the spread of any remaining cancer cells. This course of treatment has the best prognosis.

For metastatic lung tumors, the vet will recommend treatment based on where the other tumors are located in the body. Certain types of tumors are difficult to remove surgically and may be treated with chemotherapy or radiation. Unfortunately, by the time the cancer spreads to the lungs, it is usually in its aggressive final stages, resulting in a poor prognosis with a high likelihood of tumor recurrence.

In most cases of feline lung cancer, anticancer drugs may be ineffective as pulmonary cancer tends to have a strong resistance to drugs.

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The cat will be kept in the hospital until its breathing has improved and pain subsides enough to be managed at home.  

If surgery occurred, the cat will need to be confined and quiet for up to 2 weeks following the surgery in order for the surgery site to heal completely. An Elizabethan cat collar or bandage may be used in order to prevent the cat from irritating the site. 

The vet will prescribe pain medication which must be taken for several days after the surgery. The vet will schedule follow-up appointments as needed for chemotherapy or radiation treatment, as well as to check for tumor recurrence.

If the owner is an active smoker, the best thing they can do for their cat (and themselves) is to stop smoking.