AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

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

INTRODUCTION

Section 2 of 11  

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

Background

Estimates indicate that more than 5 million Americans are bitten by animals each year. Dogs and cats are involved in most of these bites. Bites from both cats and dogs require careful management, and patients may experience long-term morbidity or may even die. Cat bites have a high incidence of infection (approximately 50%), and dog bites may cause severe injury to tissues. Dog and cat populations in the United States are each estimated to exceed 50 million animals. Many households in the United States include pets, and many children are bitten by family pets.

Breeds associated with serious dog bites in children include pit bull, Rottweiler, wolf mix, Saint Bernard, German Shepherd, and Akita.

Pathophysiology

Dogs and cats have prominent canine teeth; however, great differences are observed in the structure of those teeth. Dogs have wider canines, while cats have thinner canines. Dogs are capable of exerting enormous pressure when biting, and some breeds can pierce metal plates with their teeth. In particular, the bites of large dogs can be dangerous to children. Large breeds tend to cause wounds in the head and neck areas of younger children, and their powerful jaws can penetrate the skull and destroy deep tissue. Cat bites are characterized by puncture wounds that inoculate bacteria deep into tissues.

Cats and dogs harbor a number of potentially pathogenic species of aerobic and anaerobic bacteria in the oral flora.¹ Common genera include Staphylococcus, Streptococcus, Pasteurella, and Bacteroides.² Other organisms cultured in dog bites include Capnocytophaga canimorsus and species of Eikenella, Enterobacter, Proteus, Haemophilus, and Klebsiella. Cat bites may contain Actinomyces, Fusobacterium, Peptostreptococcus, Clostridium, Wolinella, and Propionibacterium organisms. Infections should be assumed to be polymicrobial.

Frequency

United States

Estimates indicate that more than 5 million Americans are bitten by animals each year. Dog bites account for nearly 85% of the total number of animal bites, and cat bites for approximately 10%. Other animals involved in bites include rodents and other small mammals, such as ferrets and rabbits. Bites from more exotic animals (eg, snakes, lizards, monkeys, farm animals) are rare.

International

Types of animal bites can vary depending on land development and the natural flora. For example, in India, tiger bites may be encountered. In general, in North America, dogs are the agents in most animal bites.

Mortality/Morbidity

Each year, approximately 20 people die as a result of dog bites; most of these people are young children who have massive neck and head injuries resulting from the bites. The mouths in breeds of large dogs are at the height of young children's faces. Pit bulls, with powerful jaws that are capable of causing rapid and devastating damage, are responsible for nearly three fourths of all dog bite fatalities.

• Wound infection and cellulitis resulting from bacterial infections are the most common causes of morbidity.
• Bite wounds in joint spaces may be complicated by septic arthritis. Deep wounds may be complicated by osteomyelitis, and penetrating skull wounds may result in meningitis.
• Although rare, rabies can be a fatal complication of mammalian bites. The possibility of rabies should be addressed in the history.
• Puncture wounds have a higher rate of infection than lacerations. However, lacerations cause more damage to tissues.

Sex

Males are more likely than females to be bitten by dogs.³ Females are more likely than males to be bitten by cats.

Age

Animal bites are most common in children aged 5-14 years.

CLINICAL

Section 3 of 11  

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

History

Begin taking the history with prehospital care.

• Important details in the history include the type of animal that attacked the patient, behavior of the animal, and time of day the bite occurred. For instance, a raccoon bite in the daytime places the patient at higher risk of rabies exposure, as does an unprovoked attack.
• Document the address or location of the attack and the time of the attack (important).
• Ascertain ownership of the animal, current location of the animal, and rabies vaccination status.
• Document prehospital care (eg, wound cleansing).
• Document the patient's allergies, current medications, medical history, immunization status, and the time of the last meal.

Physical

• Focus physical examination initially on the ABCs.
• • Patients with animal bites rarely require resuscitation.
  • Ensure that no compromise of circulation, motor skills, or sensation is present.
  • Inspect the wounds, paying careful attention to soft tissue damage, tendon exposure or injury, bone exposure, and the presence of foreign bodies.
• Limitations of the physical examination are as follows:
• • Cat bites may appear innocuous but may violate joint space integrity.
  • Dog bites to the head may penetrate the skull, and foreign bodies (eg, teeth, fragments of teeth) may not be detected upon examination.

Causes

Bites may be either provoked or unprovoked.

• Causes of provoked attacks
• • Antagonizing an animal
  • Hurting an animal
• Causes of unprovoked attacks
• • Approaching the young of an animal
  • Approaching an animal that is eating
  • Entering the property of a territorial animal
  • Nearing an animal with rabies
• Dogs are pack animals. Many instances have occurred in which individuals were mauled by packs.

DIFFERENTIALS

Section 4 of 11  

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• Follow-up
• Miscellaneous
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Other Problems to be Considered

Wound infection
Cellulitis
Fractures
Foreign bodies
Meningitis
Cervical spine injury
Vascular injury

WORKUP

Section 5 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Lab Studies

• Laboratory testing is rarely helpful when patients with dog bites present immediately after injury. Patients who are hemodynamically unstable are an obvious exception.
• Additional laboratory testing should be performed as indicated. Usually, patients who present with infection require further workup.
• • Consider obtaining a tissue culture in patients who do not have sepsis when presenting with a wound infection.
  • Obtain a CBC count and blood culture in patients with more severe infections.

Imaging Studies

• Radiography is generally not helpful but may be useful for certain bite wounds.
• Dog bites to the head may penetrate the skull. At the minimum, perform skull radiography in a child with a dog bite to the head, especially with a bite from a large dog.
• Foreign bodies, such as tooth fragments, may be revealed by radiography. Perform radiography if the possibility of a foreign body cannot be excluded by examination.
• Patients with deep tissue injuries may have fractures. The hand and joint spaces are particularly vulnerable.
• Patients who present with signs of infection may have osteomyelitis or septic arthritis. Bone scans may reveal osteomyelitis even in patients in whom radiography findings are negative.
• Perform head CT scanning in children with penetrating skull injuries.

Procedures

• Joint aspiration may aid in the diagnosis of septic arthritis.

TREATMENT

Section 6 of 11  

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• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical Care

• Address ABCs immediately in the event of facial and neck wounds.
• Wounds should be copiously irrigated with isotonic sodium chloride solution under high pressure (usually with an 18- or 19-gauge needle or angiocatheter). Wounds may require more than 200 mL/in of isotonic sodium chloride solution.
• Infection is a feared complication of animal bites, especially cat bites. Studies have shown that infections are polymicrobial. Antibiotic coverage for staphylococci and anaerobes is necessary.
• Consider tetanus prophylaxis.
• Consider rabies prophylaxis in certain circumstances (eg, raccoon bites, bat bites, unprovoked attack by an unknown animal).

Surgical Care

Surgical treatment may be appropriate.

• Debridement is useful for removing foreign bodies and devitalized tissue, which can serve as a nidus for infection. Remove blood clots, and inspect the wound further during the procedure.
• Careful wound excision may improve the cosmetic appearance of the scar and decrease the incidence of wound infection.
• Perform primary closure in certain wounds. Facial wounds rarely become infected because the face is well vascularized. Clean wounds can also be closed. Wounds on the hands or lower extremities should be left open. Patients who have a wound older than 6 hours are best treated using delayed primary closure in lieu of primary closure.

Consultations

• Plastic surgeon for potentially disfiguring injuries
• Hand specialist for injuries to the hand
• Orthopedist for bone and joint injuries or deep structural injuries
• Neurosurgeon for penetrating wounds to the skull
• Vascular specialist for neck wounds
• Infectious disease specialist for immunocompromised patients

MEDICATION

Section 7 of 11  

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• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Amoxicillin combined with a beta-lactamase inhibitor is the most commonly used oral antibiotic. Patients who are allergic to penicillin and are tolerant of cephalosporins may be treated with ceftriaxone. Patients who are intolerant to cephalosporins may be treated with a combination of trimethoprim and sulfamethoxazole plus clindamycin. Prophylaxis may also be provided with erythromycin or a tetracycline. A 3- to 7-day course of antibiotic therapy is commonly used for prophylaxis.

Drug Category: Antibiotics

These agents are used for prophylaxis and treatment of infection. Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Drug Category: Vaccines and immune globulins

These agents provide active and passive immunization and increase resistance to infection.

FOLLOW-UP

Section 8 of 11  

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• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Further Inpatient Care

• Patients who require inpatient care include those with airway compromise, hemodynamic instability, penetrating skull injury, or severe soft tissue injuries. Patients with wound avulsion with tissue loss as well as patients with open fractures or exposed bone typically are admitted.
• Appropriate surgical subspecialties should be involved in treating patients admitted to the hospital. Decisions to incise, drain, and explore tissue should be made after surgical consultation.
• Patients who may not be compliant with outpatient antibiotic therapy may require admission. Patients who have developed signs of infection may benefit from admission.
• If osteomyelitis is suspected despite normal radiography findings, consider a bone scan.
• Patients with severe injuries may require several wound debridements in the operating room.
• Patients may develop hypovolemic shock or septic shock; these patients should be treated appropriately with isotonic crystalloids and pressors as indicated.

Further Outpatient Care

• Follow-up care is necessary within 24-48 hours for all bite wounds because of risk of infection.

Transfer

• Transfer patients who are hemodynamically unstable, have airway compromise, or have massive trauma to a tertiary care center.

Deterrence/Prevention

• Pet owners should watch animals when children are present. Children should be discouraged from approaching animals, especially when the animal is not the family pet. Children should avoid animals that are eating.
• Citizens should insist on leash laws, and pet owners should keep their animals on a leash.
• Clinicians can educate parents about the potential dangers of certain breeds and the need to be vigilant if they own a pet.

Complications

• Meningitis
• Sepsis
• Septic arthritis
• Osteomyelitis
• Cellulitis
• Wound infection
• Facial/neck deformities
• Limb deformities
• Limb loss

Prognosis

• Most patients with animal bites have a good-to-excellent prognosis.

Patient Education

• Patients and their families should receive instructions that clearly outline the signs of infection.
• Inform patients of the risk of infection as a consequence of the animal bite despite treatment with irrigation and antibiotics.
• Emphasize the need for follow-up care as well as the need to receive immediate medical attention if signs of infection develop.
• 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.

MISCELLANEOUS

Section 9 of 11  

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• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Medical/Legal Pitfalls

• Failure to consider the possibility of skull penetration
• Failure to consider the possibility of inoculation of bacteria into a joint space
• Improperly closing wounds (eg, cat bite to the hand)
• Failure to adequately document the patient's history
• Failure to adequately document treatment (eg, irrigation, antibiotic use)
• Failure to report the injury to police or the local animal control agency
• Failure to note any compromise of motor nerves, sensory nerves, or circulation
• Failure to consider hypovolemia in patients with extensive wounds

Special Concerns

• If the animal is a family pet, it may attack the child again. Consider discussing the removal of the pet with the family.
• Dogs that are left off a leash and have bitten individuals constitute a menace to the community. Dogs should always be on a leash. Aggressive dogs may require a muzzle.

MULTIMEDIA

Section 10 of 11  

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• Differentials
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• Follow-up
• Miscellaneous
• Multimedia
• References

Media file 1:  The devastating damage sustained by a preadolescent male during a pit bull attack. Almost lost in this photograph is the soft tissue damage to this victim's thigh. This patient required 2 units of O- blood and several liters of isotonic crystalloid. Repair of these wounds required a pediatric surgeon, an experienced orthopedic surgeon, and a plastic surgeon. Attacks such as these have caused a movement in some areas of the country to ban pit bulls.
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Media file 2:  Massive soft tissue damage of the right leg caused by a pit bull attack. This patient was transferred to a level one pediatric trauma center for care. At times, staff members may need counseling after caring for savagely mauled patients.
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Media type:  Photo

Media file 3:  Massive soft tissue damage of the lower left leg caused by a pit bull attack. Most of the fatalities from dog bites are children. Rottweilers and pit bulls are responsible for about 60% of fatalities.
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Media type:  Photo

Media file 4:  A different angle of the patient in Image 3 showing the massive soft tissue damage to this child's left lower leg. Pit bull attacks are not rare.
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Media type:  Photo

Media file 5:  Wounds to the left arm inflicted during a pit bull attack. This young patient was also bitten once on the left side of his face.
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Media type:  Photo

REFERENCES

Section 11 of 11

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

1. Brook I. Management of human and animal bite wounds: an overview. Adv Skin Wound Care. May 2005;18(4):197-203. [Medline].
2. Stefanopoulos PK, Tarantzopoulou AD. Facial bite wounds: management update. Int J Oral Maxillofac Surg. Jul 2005;34(5):464-72. [Medline].
3. Brogan TV, Bratton SL, Dowd MD, Hegenbarth MA. Severe dog bites in children. Pediatrics. Nov 1995;96(5 Pt 1):947-50. [Medline].
4. CID. Report of the committee on infectious diseases. In: Red Book. 24^th ed. American Academy of Pediatrics; 1997:122-6.
5. Dire DJ. Cat bite wounds: risk factors for infection. Ann Emerg Med. Sep 1991;20(9):973-9. [Medline].
6. Dire DJ. Emergency management of dog and cat bite wounds. Emerg Med Clin North Am. Nov 1992;10(4):719-36. [Medline].
7. Dos Santos LM, Abramo TJ, Schunk JE. Dog bites. Pediatr Emerg Care. Oct 1995;11(5):313-6. [Medline].
8. Fleisher GR. The management of bite wounds. N Engl J Med. Jan 14 1999;340(2):138-40. [Medline].
9. Jones N, Khoosal M. Infected dog and cat bites. N Engl J Med. Jun 10 1999;340(23):1841; discussion 1842. [Medline].
10. Litwin CM. Pet-transmitted infections: diagnosis by microbiologic and immunologic methods. Pediatr Infect Dis J. Sep 2003;22(9):768-77. [Medline].
11. Quinlan KP, Sacks JJ. Hospitalizations for dog bite injuries. JAMA. Jan 20 1999;281(3):232-3. [Medline].
12. Talan DA, Citron DM, Abrahamian FM, et al. Bacteriologic analysis of infected dog and cat bites. Emergency Medicine Animal Bite Infection Study Group. N Engl J Med. Jan 14 1999;340(2):85-92. [Medline].

Article Last Updated: Jul 14, 2008