Animal Bites in Emergency Medicine Treatment & Management
- Author: Alisha Perkins Garth, MD; Chief Editor: Joe Alcock, MD, MS more...
Obtaining the history of the bite event is of major importance, including home treatment of wounds, body parts involved, and other symptoms (see History).
Rinse bite wounds, if possible, and cover with a sterile dressing. Tap water has been shown to be as effective for irrigation as sterile saline.
Encourage patients to seek prompt care.
Emergency Department Care
Most bite wounds can be treated in the ED. Essentials of treatment are inspection, debridement, irrigation, and closure, if indicated. Complete trauma evaluation occasionally is indicated.
Carefully inspect bite wounds to identify deep injury and devitalized tissue. Obtaining an adequate inspection of a bite wound that has not been anesthetized is nearly impossible. Care should be taken to visualize the bottom of the wound and, if applicable, to examine the wound through a range of motion.
Debridement is an effective means of preventing infection. Removing devitalized tissue, particulate matter, and clots prevents these from becoming a source of infection, much like any foreign body. Clean, surgical wound edges result in smaller scars and promote faster healing.
Irrigation is a key means of infection prevention. A 19-gauge blunt needle and a 35-mL syringe provide adequate pressure (7 psi) and volume to clean most bite wounds. In general, 100-200 mL of irrigation solution per inch of wound is required. Heavily contaminated bite wounds require more irrigation. Large dirty wounds may require irrigation in the operating room. If available, povidone-iodine solution has been shown to be virucidal and is recommended for irrigation by the US Centers for Disease Control (CDC) if there is concern for rabies. A 10% solution can be diluted (10 or 20:1) and used to both cleanse the surface of the wound as well to irrigate. Additionally, isotonic sodium chloride solution or tap water is a safe, widely available, effective, and inexpensive irrigating solution. Few of the numerous other solutions and mixtures of saline and antibiotics have any advantages over tap water or saline. If a shieldlike device is used, take care to prevent the irrigating solution from returning to the wound,which decreases the effectiveness of the irrigation.
It may be difficult to appropriately irrigate small puncture wounds, especially those inflicted by the teeth of a cat. Given that these have a higher rate of infection, consideration should be given to opening the wound with a 15-blade scalpel and creating a 1-1.5cm incision that can be well irrigated and left open to heal by secondary intention.
Studies estimate the rate of infection of non – high-risk mammalian bites to be approximately 6-8% when closed primarily.[19, 20, 21] A study of dog bites showed improved cosmetic scores and no increased risk of infection with primary closure of wounds in multiple anatomic locations with provision of prophylactic antibiotics.
Facial wounds have a low risk of infection even when closed primarily due to their increased blood supply.[9, 22, 19] A randomized clinical trial showed no increased risk of infection (without the use of prophylactic antibiotics) and improved wound healing times with primary closure of facial wounds from dog bites. Given the cosmetic implications of facial wounds, primary closure is therefore advisable.
Primary closure should only be considered in bite wounds that can be cleansed effectively. Bite wounds to the hands and lower extremities, with a delay in presentation (>8-12 hours old), or in immunocompromised hosts, generally should be left open or treated by delayed primary closure. Closure management decisions should be at the discretion of the provider after discussion with the patient and consultation with specialists if available. Deep sutures should be avoided because they can act as a nidus for infection.
If a bite wound involves the hand, consider immobilizing the hand in a bulky dressing or splint to limit use and promote elevation.
Consider tetanus and rabies prophylaxis for all wounds. Antirabies treatment may be indicated for bites by dogs and cats whose rabies status can not be obtained, or in foxes, bats, raccoons, or skunks in the Americas (see Rabies and Tetanus for treatment and dosing information).
Oehler et al have established a wound management strategy following animal bites to prevent severe complications that include the following steps :
Culture for aerobes and anaerobes if abscess, severe cellulitis, devitalized tissue, or sepsis is present
Use saline solution for wound irrigation
Debride necrotic tissue and remove any foreign bodies
If fracture or bone penetration has occurred, radiography is indicated (MRI or CT may also be indicated)
Initiate prophylactic antibiotics in selected cases (based on type and specific animal species involved)
If methicillin-resistant Staphylococcus aureus (MRSA) is suspected, first-line antibiotics include trimethoprim-sulfamethoxazole, doxycycline, minocycline, and clindamycin 
Hospitalization is indicated if fever, sepsis, spreading cellulitis, severe edema, crush injury, or loss of function is present; also consider hospitalization for patients who are immunocompromised or are likely to be noncompliant
Administer tetanus booster (if none given in past year) or initiate primary series in nonvaccinated individuals (see Tetanus for further recommendations)
Assess the need for rabies vaccine and immunoglobulin (see Rabies for further recommendations)
For additional information, see Medscape's Wound Management Resource Center.
Further inpatient care and transfer
Patients with infected animal bites may need inpatient care. This depends on the general health of the patient, the extent and nature of the infection, and the patient's likely degree of compliance.
Consider admitting patients with hand bites that become infected (generally those involving deep structures). Consider consultation with the hand surgery service if deep infection, such as involving the tendon sheath or other structures, is suspected, as surgical irrigation may be indicated.
Patients who require extensive repair or prolonged inpatient care may need transfer to a tertiary care facility.
Extensive wounds, those involving tissue loss, or those involving complex structures may require plastic surgery consultation.
If the skull is penetrated, neurosurgery consultation is indicated.
Local public health authorities should be notified of all bites and may help with recommendations for rabies prophylaxis.
Complications of bite wounds may include the following:
Loss of limb
Loss of function
Pediatric patients who have been bitten remain at risk if the dog, cat, or other animal that bit them continues to be aggressive or is located where another bite could occur. To prevent further incidents, the animal should be moved to another location.
Close follow-up care is essential in animal bite wounds. Reevaluate a low-risk bite for signs of infection within 48 hours and a high-risk bite within 24 hours.
In some centers that have an observation unit, admission to that area for direct clinical observation and repeat doses of parenteral antibiotics can be considered on a case-by-case basis.
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