How should dog bites be managed to reduce risk of infection?
H. CodyMeissner, M.D., FAAP
Most of the estimated 5 million bites that occur each year in the U.S. are dog bites,
and children are more likely than adults to be bitten by a dog, according to the 2018
AAP Red Book and the Centers for Disease Control and Prevention.
Meticulous cleaning with extensive irrigation with sterile normal saline is the cornerstone
for post-exposure management of a bite to reduce the risk of infection. Some evidence
suggests high-pressure irrigation may reduce bacterial counts more effectively than
simple irrigation, although other recommendations suggest avoidance of high-pressure
irrigation because of concern that infectious agents will be driven into deeper tissue
Devitalized tissue should be debrided, and foreign material should be removed. Surgical
exploration may be needed if extensive tissue damage has occurred. Bites on the hand
and foot have a higher risk of infection, especially if the wound penetrates multiple
tissue planes. Bite wounds of the face are associated with a lower risk of infection
because of a rich vascular supply and perhaps because these wounds come to medical
attention sooner than bites in other anatomic areas. Increasing time to medical attention
is associated with increasing risk of infection.
The role of wound closure is controversial. Infectious Diseases Society of America
guidelines state that primary closure is not routinely indicated following a dog bite,
except for bites to the face (Clin Infect Dis. 2014;59:e10-52). Other wounds may be approximated. Primary closure may increase the
risk of infection, even when prophylactic antimicrobial therapy is administered.
Which of the following statements are true?
a) Commonly isolated anaerobic bacteria from a dog bite include Fusobacterium, Bacteroides, Prevotella and Peptostreptococcus species.
b) Eikenella corrodens and group A streptococcus are frequently associated with dog bites.
c) Pasteurella canis is a frequently isolated organism from a dog bite, and Pasteurella multocida is frequently isolated from cat bites.
d) The highest risk of a dog bite is outside the home.
e) The majority of dog bites are from dogs owned by the family or friends of the family.
Answer: a, c and e are true
A bite wound generally becomes colonized or infected with bacteria from the animal’s
mouth rather than by bacteria colonizing the victim’s skin. Oftentimes, multiple bacteria
including both aerobes and anaerobes can be isolated from the site of injury. Despite
numerous studies, the role of presumptive antimicrobial therapy to prevent infection
is not clear. Prophylactic therapy for three to five days appears to have some benefit
in reducing infection if initiated within 12 to 24 hours after injury.
Antibiotic prophylaxis commonly is recommended for moderate to severe wounds of the
face, hands (bites tend to involve the dominant hand), feet or genital area. Bites
involving tendon, bone or joints and bites resulting in devitalized tissue generally
are treated with antibiotic prophylaxis. All immunocompromised children are candidates
for post-exposure prophylaxis following a dog bite. Capnocytophaga canimorsus is recognized to cause bacteremia and sepsis after a dog bite, especially in children
If wound prophylaxis is indicated, amoxicillin-clavulanate is recommended. For a child
truly allergic to penicillin, trimethoprim-sulfamethoxazole plus clindamycin may be
used for oral therapy.
Infected animal bite wounds should be treated with an empiric antimicrobial agent,
such as amoxicillin-clavulanate, that is active against both aerobic and anaerobic
bacteria. For intravenous therapy, ampicillin-sulbactam or piperacillin-tazobactam
may be used. If indicated, doxycycline can be administered orally or intravenously
regardless of patient age.
Aerobic and anaerobic cultures are recommended prior to antibiotic therapy if the
bite appears infected or systemic signs of infection are present. Culture of wounds
that appear uninfected is not recommended.
When examining the wound of a dog bite, it is important to determine the depth of
penetration and injury to deeper structures; the risk of involvement of the joints,
tendon or bone; range of motion of the involved limb; type of drainage, including
purulence or malodor; nerve involvement; lymphangitic streaking; regional lymphadenopathy;
and the possibility of a foreign body such as a tooth. Wounds contaminated with soil
may involve atypical mycobacteria or fungi.
Vaccine considerations following a dog bite should include evaluation of need for
tetanus prophylaxis. Dog bites generally are not considered to be tetanus prone unless
they are contaminated with soil. If tetanus prophylaxis is indicated, an appropriate
tetanus-containing vaccine (Tdap, DTaP, DT) should be administered based on the child’s
age and vaccination history. Tetanus immunoglobulin should be considered in a child
who is incompletely vaccinated.
Tetanus toxoid should be administered to patients following a high-risk bite and without
vaccination within 10 years. Tdap is preferred if this vaccine has not been given
previously. A booster dose of tetanus toxoid vaccine should be administered for dirty
wounds if more than five years has elapsed since the last dose and for clean wounds
if more than 10 years.
Assessment for rabies risk will determine the need for rabies immunoglobulin and the
rabies vaccine series. Public health personnel in a state health department can assist
in determining the need for post-exposure rabies prophylaxis. The potential for rabies
infection is highest after a bat or carnivore bite or from a dog with uncertain rabies
vaccination status that cannot be captured for adequate quarantine.
Eikenella corrodens and group A streptococcal infections are rarely associated with dog bites. They are
constituents of normal human mouth flora and often are associated with human bites.
Most dog bites to young children occur in the home.
Dr. Meissner is professor of pediatrics at Floating Hospital for Children, Tufts Medical
Center. He also is an ex officio member of the AAP Committee on Infectious Diseases
and associate editor of the AAP Visual Red Book.