1. Bites
Presentation
Histories of animal bites are usually volunteered, but the history of a human bite,
such as one obtained over the knuckle during a fight, is more likely to be denied or
explained only after questioning. A single bite may contain various types of injury,
including underlying fractures and tendon and nerve injuries, not all of which are
immediately apparent.
What to do:
• Obtain a complete history, including the type of animal that bit, whether or
not the attack was provoked, what time the injury occurred, the current
health status and vaccination record of the animal, and whether or not the
animal has been captured and is being held for observation.
• Assess the wound for any damage to deep structures, any need for surgical
consultation, and any risk of infection. Look for bone and joint involvement
and, if present, obtain appropriate imaging studies (dog bites have caused
open depressed skull fractures in small children). Examine for nerve and
tendon injury and be aware that crush and puncture wounds as well as bites
on the hands, wrists and feet are at higher risk for development of infection
and significant complications such as tenosynovitis, septic joints, osteomyelitis
and sepsis. Bites from cats, humans, other primates* are also associated
with higher rates of infection. If tissue damage is extensive, then obtain
vascular, orthopedic, otorhinolaryngologic, reconstructive or other
consultation.
• For crush wounds and contusions, elevate above the heart and apply
cold packs.
• If the wound requires debridement, or will be painful to cleanse and irrigate,
anesthetize with buffered lidocaine (epinephrine will slightly increases
infection rates).
• If there are already signs of infection, obtain aerobic and anaerobic
cultures of any pus.
• Cleanse the wound with antiseptic (10% povidone-iodine solution, diluted
1:10 in normal saline) and sharply debride any debris and non-viable tissue.
• Irrigate the wound, using a 20ml syringe, a 19 gauge needle or an irrigation
shield (Zerowet), and at least 200ml of sterile saline or the diluted 1% povine-
iodine solution. This technique demonstrably reduces microscopic debris and
bacteria. You can use an intravenous setup to irrigate a large area.
• Prepare every wound as if you were going to suture it.
• For animal bite wounds that are clean, uninfected lacerations located
anywhere other than the hand or foot, you may staple, tape, or
suture them closed. Prophylactic antibiotics are not necessary.
Infection rates in sutured dog bite wounds have compared favorably with
those for unsutured wounds and with non-bite lacerations.

2. • If the wound is infected when first seen, plan either a delayed repair after
three to five days of saline dressings or secondary wound healing without
closure. Prescribe antibiotics (see below) for seven to ten days. Severe
infections require hospitalization for elevation, immobilization,
intravenous antibiotics and surgical consultation.
• With human bites, animal bites that are punctures or located on the hand,
wrist or foot, or bites more than 12 hours old, in most cases, you should
leave the wounds open and apply a light dressing or saline dressing and
consider delayed primary closure after two to three days. Wounds
should also be left open on debilitated and patients with diabetes, alcoholism,
chronic steroid use, organ transplants, vascular insufficiency, splenectomy,
HIV or other immunocompromising condition.
• Start prophylactic antibiotics in the ED on these wounds (see above) and
in patients with artificial or damaged heart valves and implanted
prosthetic devices. The most effective dose is the one you can give now.
Augmentin 500 mg tid for three to five days is the current CDC
recommendation for all bites. Alternatives for prophylaxis include:
o dog bites:
 for adults clindamycin (Cleocin) 150-300 mg and ofloxacin
(Floxin) 400 mg bid,
 for children clindamycin and trimethoprim/sulfamethoxazole
o cat bites: penicillin V 500 mg qid, doxycycline 100 mg bid for adults, or
ceftriaxone 500-2000 mg im/iv
o human bites: cefoxitin 2000 mg q8h iv
• If the patient has had no tetanus toxoid in the past 5-10 years, provide
prophylaxis.
• If the patient was bitten by an oddly behaving domestic animal, or a bat,
coyote, fox, opossum, raccoon, or skunk, you should start rapid rabies
vaccination with 20IU/kg of rabies immune globulin and the first of
five l mL doses of human diploid strain rabies vaccine. Reassure the
patient that bites of rodents and lagomorphs, including rats, squirrels,
hamsters, and rabbits, in America do not usually transmit rabies. Such bites
also have a low incidence of secondary infection and do not require
prophylactic antibiotics.
• Provide hepatitis prophylaxis for patients who have been bitten by known
carriers of hepatitis B. Administer hepatitis B immune globulin 0.06ml/kg
im at the time of injury and schedule a second dose in 30 days. Follow
standard guidelines applicable to contaminated needle sticks.
• Minimize edema (and infection) of hand wounds by splinting and elevation.
• Have patient return for a wound check in two days, or sooner if there is
any sign of infection. Explain the potential for serious complication such as
septic arthritis, osteomyelitis and tenosynovitis (evident when a finger
becomes diffusely swollen, immobile, tender along the flexor surface or painful
on passive extension) which will require specialty consultation.

3. What not to do:
• Do not overlook a puncture wound.
• Do not suture debris, non-viable tissue, or a bacteria innoculum into a wound.
• Do not use buried absorbable sutures, which act as a foreign body and cause
a reactive inflammation for about a month and increase the risk of infection.
• Do not waste time and money obtaining cultures and Gram stains of fresh
wounds. The results of these tests do not correlate well with the organisms
that subsequently cause infection.
• Do not routinely suture human bites.
Discussion
Animal bites are often brought promptly to the ED, if only because of a legal
requirement to report the bite, or because of fear of rabies. Bite wounds account for
1% of all ED visits in the US, most caused by dogs and cats. Most dig bites are from
household pets rather than strays. A disproportionate number of dog bites are from
German shepherds.
Bites occur most commonly among young, poorly supervised children who disturb
the animals while they are sleeping or feeding, separate them during a fight, try to
hug or kiss an unfamiliar animal or accidently frighten it. Malpractice claims and
other civil lawsuits often follow bite injuries.
Dog and cat bites both show high rates of infection with staphylococcus and
streptococcus species, as well as Pasteurella multocida and many different gram-
negative and anaerobic bacteria. In addition to these organisms, 10-30% of all
human bites are infected with Eikenella corrodens, which sometimes show resistance
to the semisynthetic penicillins, but sensitivity to penicillin. Adequate debridement
and irrigation are clearly more effective than prophylactic antibiotics, and except in
wounds that are at high risk for developing infection are often all that is required to
prevent infection of bites.
Less than 0.1% of all animal bites result in rabies. For questions of local rabies risk,
local public health services may be available and valuable support as sources of
information regarding the area's prevalence of rabies in an involved species.