By: Jennifer MacLeod, VMD, DACVS
Veterinary Specialty & Emergency Center
With warmer weather comes an increase in outdoor activities. And with outdoor activity, there is an increased number of patients presenting with wounds.
Lacerations, bite wounds, vehicular trauma and wounds of unknown etiology all increase in frequency with more animals spending time outdoors.
Extensive wounds can be very challenging. Wounds must be managed in some way until they are free of necrotic debris and infection and have a healthy granulation tissue bed before they can be closed, reconstructed or allowed to heal by second intention. This management often requires repeated daily sedation or anesthesia for wound management and dressing changes. Veterinarians are always looking for a quicker, less expensive, less labor-intensive means of managing these patients.
Some general principles for the management of any wound:
- First, assess the overall patient status. Are they in shock? Often with extensive wounds comes extensive underlying soft tissue trauma. Patients must first be stabilized.
- Assess the wound. After stabilization, the wound needs to be evaluated. Is it a clean wound? Is it dirty/contaminated? Is it a new wound or an old injury? How big is the wound and do we have an idea of what caused it? Often bite wounds appear small on the surface but it is important to remember the “iceberg effect”; a tooth hole in the skin is just the tip of the iceberg- there is often extensive underlying trauma. Is there any penetration of body cavities? Or any damage to underlying joints or vessels?
- Debridement of the wound. Once the patient is stabilized, sedation or anesthesia for wound debridement and cleaning is the first step. This also helps with further evaluation of the wound.
- Deciding on whether to close the wound or leave it open. With large extensive or irregular wounds, primary closure can be difficult if not impossible. Can it be closed? Does it need a drain? Will it need further debridement?
Some extensive, irregular wounds may benefit from vacuum-assisted wound therapy or VAC therapy. VAC therapy is the concept of applying negative pressure to the wound in order to speed healing time.
VAC therapy involves placing a porous primary dressing (foam) over the wound bed, sealing the wound area with a non-permeable, adhesive sheet, and applying continuous or intermittent vacuum through tubing connected to a fenestrated pad on the foam.
Proposed mechanisms of action of VAC therapy include:
- Increased tissue perfusion
- Enhanced formation of granulation tissue
- Reduction of bacterial contamination (although this point is controversial)
- Removal of exudative fluid from the wound
- A decrease in pro-inflammatory mediators in the wound
Use of VAC therapy requires appropriate equipment and careful patient monitoring. Appropriate care and monitoring of the patient is extremely important. Ideally, the system should be checked every two hours while in place. Loss of suction must be reported quickly as it is recommended that the wound be flushed after two hours of suction loss. The character and volume of the fluid needs to be removed from the wound and needs to be monitored. And the patient should also be monitored to ensure protein levels and hydration are being maintained.
Not all wounds are compatible with VAC therapy. Contraindications to using VAC therapy include:
- Exposed vessels, nerves, tendons or ligaments
- Bleeding or coagulation disorders
- Unprotected organs
- Eschar over necrotic tissue unless debrided first
- Unexplored wounds that could connect with chest or abdomen
Although well tolerated by most patients, some complications can be seen with VAC therapy. Complications seen with VAC therapy include loss of suction, erosion of underlying vessels causing hemorrhage, pain and lack of response to therapy.
Dr. Jennifer MacLeod, is a Board-Certified Surgeon at the Veterinary Specialty & Emergency Center. The Veterinary Specialty & Emergency Center operates state-of-the-art emergency and specialty veterinary hospitals that are open 24/7/365 in both Levittown PA and Philadelphia PA. For more information about our world-class emergency and specialty care, please visit VSEC on the web at www.VSECVET.com.
- Pitt KA, Stanley BJ. Negative Pressure Wound Therapy in 45 Dogs. Vet Surg 2014; 43:380-387.
- Demaria M, Stanley BJ, et al. Effects of Negative Pressure Wound Therapy on Healing of Open Wounds in Dogs. Vet Surg 2011; 40:658-669.
- Howe LM. Current Concepts in Negative Pressure Wound Therapy. Vet Clin Small Anim 2015; 45:565-584.