eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Reconstructive Surgery

Animal Bites

Suzanne K Doud Galli, MD, PhD, Consulting Staff, Cosmetic Facial Surgery, Private Practice
Philip J Miller, MD, FACS, Assistant Professor, Department of Otolaryngology, Division of Facial Plastic and Reconstructive Surgery, New York University School of Medicine

Updated: Jan 7, 2009

Introduction

Background

Animal bites are not uncommon occurrences. However, victims who are treated in emergency centers represent only a small percentage of all bite victims. Although notification is mandatory in many states, an estimated 50% of all dog bites are not reported.

Most animal bites are dog bites (80-90%). Cat bites make up approximately 10%, and bites from miscellaneous animals and rodents also contribute to these figures.

Most animal bites occur on the extremities, but the head and neck region is also often affected. Animal bites to the face are most commonly made by dogs or cats. Of all dog bites, 9-36% occur to the head and neck region. The head and neck region is injured in 6-20% of persons who sustain cat bites. Children are injured more frequently in the head and neck region than adults.

Most bites occur in the summer months in the late afternoon. Additionally, most bites occur in the victim's home or in the home of a friend or relative. Often, the animal is known to the victim (eg, a pet).

Pathophysiology

Although the risk of infection exists in any bite situation and proper wound management is required, animal bites to the head and neck require special considerations. The intimate juxtaposition of vital structures and the cosmetic issues of the head and neck region warrant special care for animal bite wounds to these areas.

Frequency

United States

Animal bites account for 1% of the emergency department visits in the United States. Up to 4.5 million people are treated for animal bites each year.

International

In studies from England and Scotland, animal bite injuries account for 3% of emergency department visits. In Switzerland, up to 23,000 people are treated for animal bites and scratches annually.

Mortality/Morbidity

Animal bites can lead to infection, and, if treated appropriately, patients can avoid this risk. Other complications include sepsis, osteomyelitis, septic arthritis, and even death. Fatalities are uncommon, but an average of 10-15 deaths occur following dog bites each year in the United States. Most of these fatalities are children who sustain bites to the head and neck region. Even a minor bite to a major vessel can lead to hemorrhage in a small child. Skull fractures resulting from dog bites have been reported.

Race

Epidemiologic data have failed to demonstrate an association between race and bites.

Sex

In general, animal bites occur with equal incidence in men and women. However, dog bites occur more frequently in men and boys, while cat bites occur more frequently in women and girls.

Age

Animal bites occur more frequently in adults. However, children have a higher percentage of head and neck bites. Additionally, bites in children are more likely to warrant medical attention.

Breed

The breed of the dog has been reported for some bites. Most bites (>50%) are inflicted by working dogs, which includes German shepherds, Doberman pinschers, collies, Great Danes, huskies, and mixed shepherd-type dogs. Sporting dogs, such as spaniels, retrievers, pointers, and setters, are implicated less frequently. Cats are not typically identified by breed.

Clinical

History

Although the incidence of infection transmission is quite low, the risk of rabies is probably the best reason for investigating animal bite injuries. Regardless, many animal bites remain unreported because they are minor and can be self-treated.
When evaluating a patient following an animal bite, the nature of the injury is pertinent, including whether or not the animal was known to the victim. The time of injury may have implications for treating potential wound infections or for addressing avulsed appendages.

Physical

Following an animal bite, patients require a full physical examination to address all bite wounds.
Adults are injured most often in the extremities. Children are injured more often in the head and neck region compared with adults.
The degree of injury is important. Some patients can be managed with local wound care or simple suturing by emergency department staff. Others require a consultation with a specialist or a trip to the operating room to address their wounds.

Causes

Epidemiologic studies have shown that most dog and cat bites are not from stray animals. Rather, the animal is often the pet of the victim or an acquaintance of the victim. In many animal bites in children, the animal was inadvertently provoked by the child. Infant swings have been linked to dog attacks.^{[1 ]}

Workup

Laboratory Studies

Routine laboratory studies are not mandatory in the workup following an animal bite. However, with the risk of infection or sepsis, a complete blood cell count and cultures may provide useful information for treatment.

Imaging Studies

Imaging studies are not routinely performed, except for possible fractures. An imaging study may be helpful to identify the presence of a foreign body (eg, a tooth).

Treatment

Medical Care

Thorough cleansing is adequate for contused, intact skin. If the skin is penetrated, copious irrigation is warranted. Debridement is then required to remove any devitalized tissues resulting from the crush injury of the bite.
Special consideration is given to injuries to the head and neck region because of their close proximity of vital structures and the importance of cosmesis in this region. Consultation with a specialist may be required.
Basic wound management is the sine qua non of therapy for animal bites. Treatment may include debridement, antibiotic therapy, supportive care, and, possibly, primary suturing or hospitalization with operative debridement. Of all bite injuries, 1-3% require hospitalization for surgical debridement and intravenous antibiotics. Clearly, wound severity dictates surgical management.
Tetanus toxoid is administered, and the rabies status of the animal is investigated. In the event of possible rabies exposure, human diploid vaccine can be administered.
Wounds can be classified as abrasions, lacerations, punctures, and avulsions. In the head and neck region, avulsions of special appendages are of particular concern, with the lip being the most common site of injury.
The bite of a dog can yield between 150-450 pounds of pressure per square inch, depending on the dog and its training. Therefore, although a dog bite may appear as a laceration or avulsion, it most likely has components of a crush injury. Therefore, in this type of injury, debridement is required to remove any crushed tissues. Once débrided, the laceration injury is then amenable to suturing and primary closure.
The force of a domestic cat's bite does not match that of a dog. However, its sharp teeth may cause a puncture wound into which bacterial organisms are inoculated. The risk of infection is compounded by the feline habit of paw licking, which may contaminate their claws with oral flora. The risk of infection is higher following a cat bite than a dog bite. Also, cat bites carry the risk of causing catscratch fever with resultant adenopathy. However, this is usually self-limited.
Signs of infections are typical and include rubor, dolor, calor, and edema of the tissues. Purulent discharge from the wound is another good indicator of infection. Signs of infections may appear 24-72 hours following the bite. Obtain wound cultures to guide antibiotic therapy. Blood cultures are necessary if signs of a systemic infection are present. Drain any collections.
Initial wound care mandates vigorous cleansing. This is accomplished easily with copious saline lavage under pressure. Puncture wounds also require copious lavage. Irrigation with povidone-iodine solution (Betadine) also may have an antiseptic effect.

Surgical Care

Debridement of devitalized tissues in the head and neck region is performed with care.
Surgical management can be immediate or delayed.
Laceration injuries can be closed primarily, but avulsion injuries may benefit from delayed treatment.
Injuries with significant tissue loss may require local flap treatment, composite grafts, or even vascularized flaps.

Consultations

Injuries to the head and neck region can be especially complex.
Involvement of vital structures may require consultation with a head and neck surgeon.
Because of cosmesis issues, consultation with a facial plastic surgeon may be required to ensure proper closure of a complex bite, to a repair fracture, or for reconstruction.

Medication

Injuries to the head and neck region have a lower risk of infection than injuries to the extremities. The risk of infection is increased with puncture wounds, treatment delay (6-12 h), and in patients older than 50 years. Likewise, patients who are immunocompromised are at increased risk.

The most common organisms are Staphylococcus species, Streptococcus species, Pasteurella multocida, and anaerobic organisms. No single drug of choice exists for empiric therapy (ie, no single drug targets all these organisms).

Antibiotics

Therapy must be comprehensive and cover all likely pathogens in the context of this clinical setting.

Amoxicillin and clavulanate (Augmentin)

Drug combination treats bacteria resistant to beta-lactam antibiotics.
In children >3 mo, base dosing protocol on amoxicillin content. Due to different amoxicillin/clavulanic acid ratios in 250-mg tab (250/125) vs 250-mg chewable tab (250/62.5), do not use 250-mg tab until child weighs >40 kg.

Dosing

Adult

500 mg PO tid

Pediatric

Not established

Interactions

Coadministration with warfarin or heparin increases risk of bleeding

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in renal impairment; give for a minimum of 10 d to eliminate organism and prevent sequelae (eg, endocarditis, rheumatic fever); following treatment, perform cultures to confirm eradication of streptococci

Penicillin (Beepen-VK, Pfizerpen)

Inhibits biosynthesis of cell wall mucopeptide. Bactericidal against sensitive organisms when adequate concentrations are reached. Most effective during stage of active multiplication. Inadequate concentrations may produce only bacteriostatic effects.

Dosing

Adult

500 mg PO tid

Pediatric

Not established

Interactions

Probenecid may increase effectiveness by decreasing clearance; tetracyclines are bacteriostatic, causing a decrease in effectiveness of penicillins when administered concurrently

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in renal impairment

Toxoids

These agents are used to induce active immunity against tetanus in selected patients.

Tetanus toxoid

Immunizing agent of choice for most adults and children > 7 y is tetanus and diphtheria toxoids. Necessary to administer booster doses to maintain tetanus immunity throughout life. Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen–containing product.
In children and adults, may administer into deltoid or midlateral thigh muscles. In infants, preferred site of administration is the mid thigh laterally.

Dosing

Adult

Suggested dosing
Primary immunization: 0.5 mL IM; give 2 injections 4-8 wk apart and a third dose 6-12 mo after second injection
Booster dose: 0.5 mL every 10 y

Pediatric

Administer as in adults

Interactions

Patients receiving immunosuppressants, including corticosteroids or radiation therapy, may remain susceptible despite immunization due to poor immune response; cimetidine may enhance or augment delayed hypersensitivity responses to skin-test antigens; avoid concurrent use of medication with systemic chloramphenicol because it may impair amnestic response to tetanus toxoid; concurrent use of tetanus immune globulin may delay development of active immunity by several days (interaction is nevertheless clinically insignificant and does not preclude its concurrent use)

Contraindications

Documented hypersensitivity; a history of any type of neurological symptoms or signs following administration of this product; FDA recommends that elective tetanus immunization be deferred during any outbreak of poliomyelitis because tetanus toxoid injections are an important cause of provocative poliomyelitis

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Not for use in actual tetanus infections or for immediate prophylaxis of unimmunized individuals (use tetanus antitoxin, preferably human tetanus immune globulin, instead); diminished antibody response to active immunization may be observed in patients receiving immunosuppressive therapy; better to defer primary diphtheria immunization until immunosuppressive therapy is discontinued; routine immunization of symptomatic and asymptomatic HIV-infected persons is recommended

Vaccines

In the event of possible rabies exposure, human diploid vaccine can be administered.

Rabies virus vaccine (Imovax, RabAvert)

Inactivated form of virus grown in primary cultures of chicken fibroblasts. Offers active immunity and, when used in combination with human rabies immune globulin and local wound treatment, protects postexposure patients of all age groups. Fourteen days after initiating immunization series, antirabies antibody titers reach levels well above minimal protective level of 0.5 IU/mL.
Vaccine must be injected IM and never SC, ID, or IV. In adults, inject into deltoid muscle area. In small children, administer into anterolateral zone of thigh.

Dosing

Adult

Suggested dosing
Postexposure prophylaxis (previously unvaccinated patients): 20 IU/kg as soon as possible after exposure, and a total of 5 IM doses (do not inject ID) each 1 mL on day 0, 3, 7, 14, and 28
Previously immunized patients: 1 mL IM/ID on day 0 and 3

Pediatric

Administer as in adults

Interactions

Corticosteroids, antimalarials, and other immunosuppressive agents may reduce protective efficacy; persons receiving immunosuppressive therapy should receive rabies immune globulin (3 doses/mL each) by the IM route

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in documented hypersensitivity (may pretreat such patients with antihistamines); never inject rabies vaccine in gluteal area; epinephrine injection (1:1000), volume replacement, oxygen, and corticosteroids must be immediately available to counteract anaphylactic reactions that may occur

Follow-up

Further Inpatient Care

For most animal bites, local wound care with thorough cleansing and perhaps suturing of wound edges may be adequate treatment. Not all authors recommend the routine use of antibiotics following these treatments. However, in the event of more extensive injury or the development of infection, hospitalization may be required.
With larger animal bites, bedside debridement may not be adequate. In situations with large amounts of tissue loss or an avulsed appendage, surgical debridement of the wound with immediate reconstruction or salvage of an appendage may be required.

Further Outpatient Care

Patients who are treated and released are advised to return for consultation in the event of local infection or sepsis.
Patients treated with suturing require follow-up for removal of sutures and wound care, and some patients may be monitored on an outpatient basis for local wound care.

Inpatient & Outpatient Medications

The routine use of antibiotics for all bite wounds has not been established.
Often, persons treated on an outpatient basis are given an oral antibiotic, especially with puncture wounds or wounds that require debridement and suturing.
Patients who are admitted and patients who are septic require intravenous antibiotics. Analgesics are prescribed as necessary.

Transfer

If an injury is extensive and has resulted in the loss of a significant amount of tissue or an appendage, the patient may be transferred to a tertiary care referral center. There, a patient can be treated with a vascularized free flap or replantation of the appendage.

Deterrence/Prevention

Exposure to animals is clearly a risk.
The best preventative strategy is to avoid aggressive behavior with animals and avoid unfamiliar animals.
Teaching young children to avoid unnecessary provocation of animals may lead to fewer incidents of animal bites.
Not leaving children unattended in the presence of animals may also prevent attacks.

Complications

Complications can be considered immediate or delayed.
Immediate complications include loss of appendage or disfigurement, which may warrant more extensive reconstruction later. Otherwise, infection is the most common complication of animal bites, which may prompt patients who were previously untreated or self-treated to seek treatment for their injuries.
Additional complications associated with infection (eg, sepsis, osteomyelitis, septic arthritis) must be avoided or treated appropriately.

Prognosis

Animal bites lead to few fatalities, and most bites are not treated.
Even in complicated cases with extensive tissue loss or infection, the prognosis is generally excellent.

Patient Education

Education is the key to prevention. This is pertinent, especially for children, who are at higher risk for a more serious bite injury.
Children can be educated at a young age to avoid strange animals and to avoid aggravating familiar animals.
The small size of children puts them at risk for aggressive, dominating behavior by animals.
For excellent patient education resources, visit eMedicine's Bites and Stings Center and Bacterial and Viral Infections Center. Also, see eMedicine's patient education articles Animal Bites and Rabies.

References

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Keywords

animal bites, animal bite, bite, dog bite, cat bite, mammalian bite, bite wound, bite infection, animal bite wound, animal attack, dog attack, cat attack, bite victim, rodent bite, rat bite, mouse bite, raccoon bite, animal bite injury, cat scratch fever, catscratch fever, cat-scratch fever

Contributor Information and Disclosures

Author

Suzanne K Doud Galli, MD, PhD, Consulting Staff, Cosmetic Facial Surgery, Private Practice
Suzanne K Doud Galli, MD, PhD is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngic Allergy, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Rhinologic Society, and Triological Society
Disclosure: Nothing to disclose.

Coauthor(s)

Philip J Miller, MD, FACS, Assistant Professor, Department of Otolaryngology, Division of Facial Plastic and Reconstructive Surgery, New York University School of Medicine
Philip J Miller, MD, FACS is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngic Allergy, American College of Surgeons, American Medical Association, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Medical Editor

Clark A Rosen, MD, Director, University of Pittsburgh Voice Center; Associate Professor, Department of Otolaryngology and Communication Science and Disorders, University of Pittsburgh School of Medicine
Clark A Rosen, MD is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Medical Association, and Pennsylvania Medical Society
Disclosure: Bioform Medical Consulting fee Consulting

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Dominique Dorion, MD, MSc, FRCSC, Program Director and Division Chair, Professor of Surgery, Division of Otolaryngology, University of Sherbrooke, Canada
Disclosure: Nothing to disclose.

CME Editor

Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders
Christopher L Slack, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine
Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Head and Neck Society
Disclosure: Covidien Corp Consulting fee Consulting; US Tobacco Corporation unstricted gift unknown

Further Reading