AUTHOR AND EDITOR INFORMATION

Section 1 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

INTRODUCTION

Section 2 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

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.

The majority of 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, 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 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 each year.

Breed

The breed of the dog has been reported for some bites. The majority of 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.

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.

CLINICAL

Section 3 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

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 by stray animals. Rather, the animal is often the pet of the victim or an acquaintance of the victim. In many bites in children, the animal was inadvertently provoked by the child. Infant swings have been linked to dog attacks.

WORKUP

Section 4 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

Lab 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

Section 5 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

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 debrided, 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

Section 6 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

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).

Drug Category: Antibiotics

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

Drug Name	Penicillin (Beepen-VK, Pfizerpen)
Description	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.
Adult Dose	500 mg PO tid
Pediatric Dose	Not established
Contraindications	Documented hypersensitivity
Interactions	Probenecid may increase effectiveness by decreasing clearance; tetracyclines are bacteriostatic, causing a decrease in effectiveness of penicillins when administered concurrently
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Caution in renal impairment

Drug Category: Toxoids

Used to induce active immunity against tetanus in selected patients.

Drug Category: Vaccines

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

FOLLOW-UP

Section 7 of 8  

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

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.

In/Out Patient Meds

• 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

Section 8 of 8

• Authors and Editors
• Introduction
• Clinical
• Workup
• Treatment
• Medication
• Follow-up
• References

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• Galloway RE. Mammalian bites. J Emerg Med. Jul-Aug 1988;6(4):325-31. [Medline].
• Goldstein EJ. Bite wounds and infection. Clin Infect Dis. Mar 1992;14(3):633-8. [Medline].
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• Marcy SM. Infections due to dog and cat bites. Pediatr Infect Dis. Sep-Oct 1982;1(5):351-6. [Medline].
• Massari M, Masini L. Relationships among injuries treated in an emergency department that are caused by different kinds of animals: epidemiological features. Eur J Emerg Med. Jun 2006;13(3):160-4. [Medline].
• Matter HC, Sentinella Arbeitsgemeinschaft. The epidemiology of bite and scratch injuries by vertebrate animals in Switzerland. Eur J Epidemiol. Jul 1998;14(5):483-90. [Medline].
• Oberascher G, Muss N, Gruber W, Albegger K. [Animal bite injuries in the head and neck area and their care]. HNO. Oct 1985;33(10):443-8. [Medline].
• Pinckney LE, Kennedy LA. Fractures of the infant skull caused by animal bites. AJR Am J Roentgenol. Jul 1980;135(1):179-80. [Medline].
• Sacks JJ, Kresnow M, Houston B. Dog bites: how big a problem?. Inj Prev. Mar 1996;2(1):52-4. [Medline].
• Stucker FJ, Shaw GY, Boyd S, Shockley WW. Management of animal and human bites in the head and neck. Arch Otolaryngol Head Neck Surg. Jul 1990;116(7):789-93. [Medline].
• Weiss HB, Friedman DI, Coben JH. Incidence of dog bite injuries treated in emergency departments. JAMA. Jan 7 1998;279(1):51-3. [Medline].

Article Last Updated: Aug 1, 2006