Intrathoracic Mass Removal in Dogs

An intrathoracic mass is a tumor located within the chest cavity. Most commonly an intrathoracic mass is associated with the lungs, but can also involve tumors of the lymph nodes in the chest, the thymus, or even the heart. 

Each patient must be carefully assessed prior to surgery, to ensure that they will benefit from the procedure in the mid to long term. Typically, a dog with a solitary lung tumor is considered a good candidate for surgery, given that removal of a primary lung tumor may be curative. However, a poor candidate is the dog with multiple secondary lung tumors as they are liable to recur swiftly after removal. 

Most intrathoracic surgical procedures are performed at referral centers. This is in part due to the complexity of the surgery, but also because of the need for special anesthetic nursing and post-operative care. 

Pre-surgical planning is key. MRI or CT scans of the chest will map out the borders of the mass and the structures it is closest to. Thus the surgeon can pre-plan if the aim is to remove the lump in its entirety or debulk it prior to chemotherapy or radiotherapy. 

Strict surgical asepsis is essential. The surgeon gains entry to the chest either by a lateral approach where the chest is opened between two ribs, or by a medial sternotomy. The later is more invasive but gives better visualization of both halves of the chest and all its structures. 

The surgeon carefully dissects the mass away from adjacent structures, and removes it with as wide a surgical margin of healthy tissue as possible. 

A drain is placed in the chest and then the chest wall closed. The drain facilitates the removal of air and fluid from the chest after the operation is complete. The patient is carefully monitored for 24 to 48 hours after surgery until they are breathing without distress or discomfort. 

There is a wide spectrum of possible outcomes, from improving the ability to breathe to complete cure. This will depend on the size, location, and invasiveness of the mass. In some cases, the aim is to debulk (make smaller) the mass so that it interferes less with the lungs and heart. In these cases, follow up radiotherapy or chemotherapy is needed in order to keep the patient in remission for as long as possible. 

Without surgery, often the patient has a poor outlook, and the only option is medical control to try and ease breathing and reduce the size of the mass. This can offer a short-term improvement with the aim of maximizing quality of life, rather than length of life. 

Thoracic surgery is high risk and the danger period extends a few days beyond the actual surgery. Postoperatively, air in the chest cavity or fluid seepage compresses the lungs and makes breathing difficult, hence the importance of a chest drain that is monitored hourly initially, to make sure it is draining. 

The patient will be in pain for several days postoperatively and on strong, morphine-related painkillers. Once through this initial period, the dog should slowly become more comfortable and regain some of their former energy. 

Regular follow-up chest radiographs are taken, usually at three monthly intervals, to monitor for recurrence. 

Initial costs include radiography at the first opinion practice for $500 to 600. The referral consultation is around $200, with an MRI scan in the region of $1,500. Expect the procedure and postoperative care to average around $7,000.

This is a matter of balancing the dog's current quality of life and the predicted outcome if nothing is done vs. having surgery. Intrathoracic mass removal is a major procedure and should be undertaken only if the dog stands to benefit in terms of a longer period or better quality life. 

This type of surgery is not without risk and the pros and cons should be carefully discussed with the specialist prior to deciding to go ahead.

Aside from the inhalation of secondhand cigarette smoke, there are few predisposing factors to the development of intrathoracic masses in the dog. Breed may play a part, with Golden retrievers and beagles being more prone than other breeds to thyroid cancer with secondary spread to the lungs.