Animal Bite Injuries

Frederick Ilgenfritz, MD
Bitterroot General & Vascular Surgery

Bite injuries, particularly those with some tissue removed can result in significant cosmetic and functional problems. This problem is fairly common; about 50% of the population will at some point in their life suffer an animal bite. Animal bite wounds account for about 1% of all emergency room visits. Examples of animals inflicting bites in the Bitterroot would include dog, cat, horse, donkey, bear, wolf, lion, raccoon, badger, and reptiles.

Management of bites requires both local wound and systemic attention. The principles of management of bite wounds include evaluation, complete wound cleansing and removal of dead and damaged tissue. Involvement of the tendon, joints, nerves and blood vessels should be checked. All foreign material needs to be removed including dirt, sticks, stones, broken teeth and hair.

A major concern in all bite wounds is infection due to the presence of the large number of bacteria in the animal's mouth. All bite wounds are considered contaminated. The risk of infection is related to the species of animal, bite location, time until wound treatment, type of wound, and preexisting patient illnesses. Typically the infections are polymicrobial, with mixed aerobic and anaerobic species.

Antibiotic therapy is appropriate for infected bite wounds and fresh wounds considered at risk for infection, such as large wounds, large hematoma, full-thickness skin punctures and wounds with tissue loss. The most common antibiotics advocated are amoxicillin/clavulanate or a combination of amoxicillin and cephalexin. Generally, five days of prophylactic antibiotic coverage is adequate. Tetanus and rabies prophylaxis should be considered for all bite wounds. Rabies shots are given if the rabies status of the animal isn't known and the animal has not been recovered to test it.

The basic principles of surgical management of bite wounds include proper mechanical cleansing and debridement. High-pressure irrigation is an important means of wound cleansing. Adequate debridement with removal of devitalized tissue, particulate matter, and clots helps to prevent infection. Clean surgical wound edges result in better scars and quicker healing. In wounds made by large animals, there may be significant tissue loss or additional crushing injury. These wounds will require more prolonged dressing care to stabilize them, and then possibly flap transfers or other complex reconstructions.

Immediate closure/reconstruction may be considered in relatively clean bite wounds or wounds that can be cleansed effectively so as the possibility of infection has been reduced. Areas of cosmetic concern such as facial wounds, because of the excellent blood supply are at low risk for infection and should be closed right away. In other areas, a short period of aggressive wound care followed by delayed closure/reconstruction results in better long-term result.

Animals are a part of Bitterroot life. Even with the best of intentions and due care, not all interactions with these animals are positive. When a bite occurs, quick attention to basic first aid and appropriate referral to the emergency room and surgical care will result in the optimal recovery.

Questions or comments can be addressed to Frederick M. Ilgenfritz, MD, FACS, c/o Bitterroot General & Vascular Surgery, 1150 Westwood Drive, Suite C, Hamilton, MT 59840 or visit



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