SURGERY: WOUNDS, JOINTS, CRIBBERS, AND ABDOMEN


should be lavaged and cleaned at each bandage change and new sterile gauze packing inserted into the wound. To promote granulation tissue forma- tion, topical medications can be applied to the gauze before it is packed into the wound. Additionally, 15 to 30 mL of procaine penicillin G (300,000 IU/mL) can be applied to the gauze to provide local admin- istration of antibiotics.


Secondary Complications


Fig. 1. Caudoventral-craniodorsal view of a horse with a wound in the left axilla. A 35-mL plastic syringe with an attached 18-gauge needle is used to irrigate the wound with sterile saline.


bandage should be placed around the thorax and axillary region to keep the stent in place and covered (Fig. 2). The horse should be administered flunixin meglu-


mine (1.1 mg/kg, q 12 h, IV) and broad-spectrum antibiotics. A tetanus toxoid should also be admin- istered. To help avoid progressive accumulation of air within the soft tissue, limiting movement is in- dicated. Therefore, the horse should be on strict stall rest until the wound is healed. The horse can be allowed to lie down, but if he rolls or is very active in the stall he should be cross-tied to prevent exces- sive movement. The bandage should be changed every 24 to 48


hours or as needed, on the basis of the amount of drainage and condition of the bandage. The wound


Subcutaneous emphysema may develop as a second- ary complication. Subcutaneous emphysema may not be present on initial evaluation of the horse; it develops as air progressively accumulates in the subcutaneous tissue as the wound acts as a one-way valve. Once the source of the subcutaneous emphy- sema has been addressed, residual subcutaneous emphysema is usually self-limiting and rarely re- quires additional treatment. However, if the sub- cutaneous emphysema is extensive and the risk of complications from the amount of subcutaneous em- physema is high, small intravenous catheters may be inserted subcutaneously to aspirate some of the air.3 Inserting subcutaneous catheters is not with- out its own potential complications (ischemia of overlying skin, local infection); therefore, this tech- nique should only be performed when deemed nec- essary to prevent complications from subcutaneous emphysema. Additionally, the horse’s temperature should be monitored because the subcutaneous em- physema has an insulation-like effect. At warmer times of the year or in warm climates, there is a potential for serious hyperthermia. When subcutaneous air dissects through the mus-


Fig. 2. Horse with an axillary wound that has been cleaned, packed, and sealed. A stent and thoracic bandage have been applied to hold the packing in place.


486 2013  Vol. 59  AAEP PROCEEDINGS


cle layers and fascial planes into the mediastinum, pneumomediastinum ensues. A diagnosis of pneu- momediastinum is based on radiographic findings. Otherwise, pneumomediastinum in the horse is of- ten clinically silent and there is no specific treat- ment beyond treatment of the underlying cause. Cases should be monitored for complications includ- ing pneumothorax, impairment of venous return to the heart, and rupture of the mediastinal pleura, which has been reported in humans but is yet to be reported in horses.4 If pneumomediastinum progresses, it can result in pneumothorax and specifically a tension pneumo- thorax. Tension pneumothorax occurs when a flap of skin or soft tissue acts as a one-way valve, allow- ing air into the cavity on inspiration but preventing its escape on expiration. This is a rapidly progres- sive form of pneumothorax that classically consists of progressive respiratory distress, tachycardia, hy- potension, and absent lung sounds. Delays in the development of pneumothorax are commonly en- countered; therefore, serial evaluations should be performed to identify progressive changes in pulmo- nary function. Radiographs or ultrasound can be used to confirm the diagnosis. However, when sub- cutaneous emphysema is present, ultrasound has limited diagnostic value to evaluate a pneumotho-


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