Which dogs bite? A case-control study of risk factors.

OBJECTIVE Dog bites cause an estimated 585,000 injuries resulting in the need for medical attention yearly and children are the most frequent victims. This study sought to determine dog-specific factors independently associated with a dog biting a nonhousehold member. METHODS A matched case-control design comprising 178 pairs of dogs was used. Cases were selected from dogs reported to Denver Animal Control in 1991 for a first-bite episode of a nonhousehold member in which the victim received medical treatment. Controls were neighborhood-matched dogs with no history of biting a nonhousehold member, selected by modified random-digit dialing based on the first five digits of the case dog owner's phone number. Case and control dog owners were interviewed by telephone. RESULTS Children aged 12 years and younger were the victims in 51% of cases. Compared with controls, biting dogs were more likely to be German Shepherd (adjusted odds ratio (ORa) = 16.4, 95% confidence interval (CI) 3.8 to 71.4) or Chow Chow (ORa = 4.0, 95% CI 1.2 to 13.7) predominant breeds, male (ORa = 6.2, 95% CI 2.5 to 15.1), unneutered (ORa = 2.6, 95% CI 1.1 to 6.3), residing in a house with > or = 1 children (ORa = 3.5, 95% CI 1.6 to 7.5), and chained while in the yard (ORa = 2.8, 95% CI 1.0 to 8.1). CONCLUSIONS Pediatricians should advise parents that failure to neuter a dog and selection of male dogs and certain breeds such as German Shepherd and Chow Chow may increase the risk of their dog biting a nonhousehold member, who often may be a child. The potential preventability of this frequent public health problem deserves further attention.