Median Sternotomy in Dogs

Median sternotomy is a surgical procedure, also known as a sternal split, which allows the surgeon access to both halves of the chest cavity. Other means of entering the chest include intercostal thoracotomy and rib removal. 

The choice of technique depends on the location of the pathology within the chest cavity. In circumstances such as bleeding or a purulent discharge within the chest where the exact origin is not known, then median sternotomy is preferred. This is because of the greater field of vision with access to both right and left lungs, as well as the heart and structures in the mediastinum. 

Sternotomy may be performed in first opinion practice, but in reality rarely is. Many of the conditions requiring open chest surgery are diagnosed using sophisticated imaging such as an MRI scan, and therefore referral is likely. 

The patient is first stabilized, then given a general anesthetic. The dog is positioned lying on their back and the fur clipped from the entirety of the chest area. The skin is aseptically prepared and the dog draped. 

The surgeon makes a long skin incision over the center of the chest and dissects down until the central sternum is exposed. The latter is made from tough cartilage and an orthopedic rotary saw is needed to cut through in a longitudinal direction. 

The chest is then opened and the sternum held apart using retractors. A chest drain is placed as the operation draws to an end. Once the surgeon has completed the desired surgery the retractors are removed. The sternum is held together either with wire or non-absorbable suture material. The skin wound is repaired and the patient woken. 

Sternotomy is a means to an end, with the aim of giving the surgeon access to the chest cavity. This surgical approach gives superior visualisation of the chest, over other techniques such as intercostal thoracotomy. 

The decision about which technique to use is based on the need for access, rather than one of pain or recovery times. Sternotomy is not proven to be more or less painful than other ways of entering the chest, and recovery times are similar. 

This is painful surgery and the patient is given strong pain relief ahead of surgery. This is often maintained during and after the operation with a constant rate infusion of an opioid-type painkiller. In addition, the surgeon may use nerve blocks or local anesthesia to reduce discomfort. 

Sternotomy is not undertaken lightly and significant complications can arise. These include: 

• Continued bleeding or fluid buildup within the chest
• Air leakage into the chest causing the lungs to collapse
• Excessive pain at the sternotomy site
• Breakdown of the wires or sutures holding the sternum together
• Infection of surgical site
• Complications with the chest surgery

The patient may spend several days in intensive care. This facilitates careful monitoring of their discomfort as well as regular emptying of the chest drain. If all goes well, the patient may be discharged a few days after surgery. Skin sutures are removed at the 10 to 14 day point. The patient should avoid vigorous exercise for a period of weeks following surgery. 

In 2010, Shelby, a Labrador hit the news as the dog that underwent an $10,000 operation. Shelby had a condition called spontaneous pneumothorax, which required a median sternotomy to repair. This illustrates that sternotomy is part of a wider procedure, of which the costs are going to be in the thousands of dollars. This is most especially true because of the intensive care nursing necessary during the recovery period, which can cost $600 per night.

Median sternotomy is a major procedure that is only undertaken when there is a proven benefit to the patient. Typically, this is driven by a diagnosis of life-threatening chest pathology which requires surgery to correct. 

Complications are not unknown and so the risks and benefits need to be carefully assessed by the surgeon and discussed with the owner. In most cases, the patient's long term survival would be unlikely without surgery, so the benefits outweigh the risks. 

When sternotomy is required to correct a congenital heart defect, then that animal should not be bred from. In addition, careful assessment of the parent dogs is required in order to decide if it is ethical to breed from them again. 

Trauma to the chest can result in bleeding, free fluid, air, or infection in the chest cavity. The biggest single cause of trauma in the dog are road traffic accidents. Thus, dogs should be restrained on a leash near roads, and obedience trained to stop on command.