Bite, Animal

Basics

Animal bites are common and account for ∼1% of ED visits
Most bites are from provoked animals
Dog-bite wounds:
- Large dogs inflict the most serious wounds (pit bulls cause the most human fatalities)
- Most fatalities in children (70%) due to bites to face/neck
- Dogs of family or friends account for most bites
Cat-bite wounds:
- Majority from pets known to victim
- 50% infection rate in those seeking care
- Puncture wounds most frequent due to sharp, thin teeth causing deep inoculation of bacteria
Cat scratch disease (CSD):
- 3 of the following 4 criteria:
  - Cat contact, with presence of scratch or inoculation lesion of the skin, eye, or mucous membrane
  - Positive CSD skin test result
  - Characteristic lymph node histopathology
  - Negative results of lab studies for other causes of lymphadenopathy
Rat-bite wounds:
- Occur in lab personnel or children of low socioeconomic status
- Rat-bite fever (RBF), rare in the U.S. but high mortality rate
- Rat bites rarely transmit rabies, and prophylaxis not routine unless animal is suspected to be rabid

Dog and cat bites:
- Pasteurella multocida is the major organism in both:
  - Twice as likely to be found in cat bites than dog bites
  - Gram-negative aerobe found in up to 80% of cat infections
  - Infection appears in <24 hr
- Staphylococcus or Streptococcus:
  - Infection appears in >24 hr
- Other organisms include anaerobes and Capnocytophaga canimorsus (dogs)
CSD:
- Caused by Bartonella henselae
Rat bites:
- Caused by Spirillum minus and Streptobacillus moniliformis (RBF)

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