Animal Bites

Updated: Jan 27, 2017
  • Author: Suzanne K Doud Galli, MD, PhD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Overview

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. See the image below.

Animal bites. The devastating damage sustained by Animal bites. The devastating damage sustained by a preadolescent male during a dog 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 certain dog breeds.

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). Indeed, a retrospective study by Kumar et al indicated that in pediatric patients, dog bites to the head, face, and neck requiring neurosurgical consultation often are inflicted by the family pet, in most cases a large-breed dog who has manifested no previous incidents of aggression. In such patients, according to the study, the cranial vault is commonly injured, with the most frequent injury being depressed skull fracture. [1]

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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.

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Epidemiology

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.

A study by Garvey et al of morbidity in pediatric dog bites, using data from a level one pediatric trauma center, found that 69% of patients required surgery. According to the report, which involved 282 pediatric patients (median age 5 years), surgical procedures included laceration repairs (76%), tissue transfers (14%), and neurosurgical operations (2%), with the most severe traumas consisting of laryngotracheal transection, intracranial hemorrhage, depressed skull fracture, and bilateral orchiectomy. No deaths occurred among the study’s patients. [2]

A Swiss study of dog bites indicated that wounds to the hand are at particular risk of developing secondary infectious complications. This may relate to the proximity of bradytrophic tissue, such as the tendons, to the surface of the skin, and a lack of natural anatomic barriers in the hand, which allows infection to spread. [3]

A prospective, multicenter, observational study by Tabaka et al indicated that among patients with dog bite wounds, those with puncture wounds or wounds that are closed during treatment have a high infection risk and should be considered for prophylactic antibiotic therapy. The study involved 345 dog bite patients, 18 of whom (5.2%) developed wound infections. [4]

A study by Babovic et al of 193 patients who had suffered a cat bite injury indicated that risk factors for hospitalization following a cat bite include the following [5] :

  • Smoking
  • Immunocompromised state
  • Wound location over a joint or tendon sheath
  • Erythema and swelling at presentation

The investigators did not find evidence that the length of time between bite and presentation affected the likelihood of hospitalization. They also found no link between hospitalization and the patient’s white blood cell count, C-reactive protein values, and erythrocyte sedimentation rate. [5]

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.

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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.

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