Lung Lobectomy

In dogs and cats, tumors affecting the lung lobes (“pulmonary” tumors) are most often metastatic, meaning cancer cells have traveled through the bloodstream and implanted in the lungs. Tumors that originate in the lungs (primary lung lobe tumors) are much less common. Most primary tumors arise from glandular tissue and are typically classified as adenocarcinoma or bronchogenic carcinoma, but they may also develop from supportive lung tissues, such as:

• fibrosarcoma (from fibrous tissue)
• chondrosarcoma (from cartilage)
• hemangiosarcoma (from blood vessels)
• other tissue origins

Dogs and cats exposed to secondhand smoke or certain environmental pollutants (e.g., asbestos) appear to have increased risk for primary lung tumors. Brachycephalic breeds (bulldogs, pugs, etc.) may also be at higher risk than long-nosed breeds.

Pets with primary lung tumors are typically middle-aged or older. About 25% of dogs and cats with a primary lung tumor may show no obvious signs, and the mass is sometimes found incidentally on chest x-rays taken for another reason. When signs occur, they commonly include:

• cough
• weight loss
• lethargy

Large tumors or those compressing important structures can lead to breathing difficulty or regurgitation (food returning suddenly after eating). Some pets develop lameness, either because the tumor has spread elsewhere or due to hypertrophic osteopathy, a syndrome involving swelling and bony changes along the toes and lower limb bones.

Thoracic radiographs (x-rays) or a chest CT scan are used to diagnose lung tumors (Figure 1). On plain radiographs, lung tumors may not be readily visible until they are at least ~0.5 inch in diameter. Tumors that are large and/or close to the chest wall can sometimes be sampled using a needle and syringe, and the sample is examined microscopically to identify tumor type.

Because many affected pets are older, bloodwork and urinalysis are commonly performed to assess overall health and detect concurrent disease. Additional screening—such as abdominal ultrasound—may be recommended to look for a primary tumor elsewhere in the body.

Figure 1. Lung lobe tumor in a caudal (rear) lung lobe of a dog, measuring 47.8 mm (almost 2 inches) in diameter.

A single lung lobe tumor is typically treated by surgical removal (lung lobectomy), performed either through:

• a standard open chest approach (a larger incision), or
• minimally invasive surgery using several small incisions with a thoracoscope

If multiple lung lobe tumors are present, metastatic disease is most likely, and non-surgical options such as chemotherapy may be discussed.

Dogs and cats have two lungs (right and left), each divided into lobes that can be removed separately. Most lobectomies are performed via a thoracotomy, an incision on the side of the chest just behind the front leg. The incision is made between ribs, which are gently spread and then closed after the lobe is removed. The lobe’s blood supply and airway (bronchus) are sealed using sutures or (more commonly) a surgical stapler.

A chest tube is placed to remove air or fluid after surgery and may also be used for delivery of local anesthetic for pain control. Chest tubes are commonly kept in place for 12–24 hours. Pain control may include combinations of:

• epidural anesthesia
• intravenous medications
• fentanyl patches
• oral medications once the pet is awake

After surgery, pets remain hospitalized until the chest tube is removed, breathing is stable, and pain is controlled with oral medication. Activity is usually restricted for 10–14 days to allow healing. Some dogs may wear a bandage for 1–2 weeks and/or an e-collar to prevent self-trauma. Depending on histopathology results, chemotherapy may be advised. Follow-up chest imaging may be recommended to monitor for recurrence or spread.

Anesthesia carries higher risk in older pets, and risk increases further when significant airway disease is present. Some animals require mechanical ventilation during surgery. Potential complications include bleeding and air leakage if vessels or the bronchus do not seal properly. Adequate pain control is important because painful animals may not breathe deeply enough and can become oxygen-compromised. Despite these risks, most dogs and cats recover successfully.

Because the incision is near the front leg, some dogs may be stiff or have difficulty walking—especially on stairs—for up to 2 weeks, and swelling along the incision is common for several days.

Reported survival after lobectomy for primary lung tumors is often one year or longer. Longer survival is associated with smaller tumors or peripheral location (15–17.5 months), small lymph nodes (~20 months), and complete tumor removal. Survival also varies with tumor type; for example, dogs with completely removed adenocarcinomas have been reported to live longer (~19 months) than dogs with squamous cell carcinomas (~8 months). Best outcomes are reported in small, well-differentiated papillary carcinomas diagnosed before clinical signs and without lymph node spread. Cats more commonly have spread at diagnosis, so prognosis may be less favorable.

Reducing exposure to secondhand smoke is considered an important preventive measure; smoke residues can also be carried indoors on hair and clothing even when owners smoke outside.