In this issue

Issue 11

July 1997

Innovative CHIRRP project focuses on dog bites

by Jasline Flores, CHIRPP Coordinator, Hôpital de l'Enfant-Jésus (Centre de santé publique de Québec); Janet Brown, Analyst, Child Injury Division; Susan G . Mackenzie, Senior Epidemiologist, Child Injury Division; and Pierre Maurice, CHIRPP Director, Hôpital de l'Enfant-Jésus (Centre de santé publique de Québec)

At their February 1995 annual meeting, CHIRPP coordinators decided to work together on an innovative project. Acting on a suggestion by Maureen Cullingham, who is in charge of CHIRPP communications, the group agreed to examine the problem of dog bites. These injuries are a well-known reason for emergency room visits, and a review of the literature showed that little had been written on the subject in Canada.

The objective of the study was to describe the causes and circumstances surrounding dog bites in order to facilitate the development of preventive strategies. The study team used CHIRPP and other data from eight emergency departments. In recent years, the media and, in turn, the public have focused a great deal of attention and concern on the serious consequences of dog bites for children. News reports in some of Canada's urban centres have featured incidents of children being disfigured as a result of dog bites. Debates have ensued about regulating or banning certain dog breeds and about using legislation to make dog owners more accountable. Opinion on these issues remains divided among physicians, parents, politicians, dog trainers, dog breeders and veterinarians.

Statistics Canada mortality data show that an average of one Canadian a year died from dog bites between 1991 and 1994. National morbidity data for 1993 show that 656 Canadians were hospitalized that year for dog bites, a rate of 2.3 per 100,000. Children younger than 10 were four times as likely (7.0/100,000) to be hospitalized as people aged 10 and older (1.6/100,000). In the United States, an average of 17 people die every year from dog bites (Sacks, Sattin, et al. 1989). American studies also show that children visit emergency departments for dog bites 3.2 times more often than adults (Sacks, Kresnow, et al. 1996) and that newborns are 139 times more likely to die from a dog bite than adults aged 30-49 years (Sacks, Lockwood, et al. 1996). The vulnerability of children to dog-bite injuries, particularly on the face, is often attributed to the fact that their small size makes them less intimidating to dogs. Moreover, immaturity and lack of judgment sometimes lead children to act in ways that animals perceive as threatening or aggressive (Rosenberg, Dos Santos, et al. 1995).

Data collection

Of the 16 CHIRPP hospitals, six pediatric hospitals and two general hospitals took part in the study: British Columbia's Children's Hospital (Vancouver), the Children's Hospital (Winnipeg), the Children's Hospital of Western Ontario (London), The Hospital for Sick Children (Toronto), The Montreal Children's Hospital, Hôpital Ste-Justine (Montreal), Hôpital de l'Enfant-Jésus (Quebec City), and the Centre hospitalier régional de Rimouski . The general hospitals provided information on adult victims as well as on children.

The study team used three data sources to obtain as much information as possible on these injuries: the CHIRPP form, the medical file, and telephone interviews. Each hospital's CHIRPP coordinator compiled the information from the medical files and conducted the interviews. They contacted all patients or parents who had indicated a dog-bite injury on the CHIRPP form and had given their consent to be contacted for follow-up. During the interview, the participants completed a detailed questionnaire comprising 28 questions regarding the dog, the location, the exact circumstances of the incident, and the consequences to the dog.

The eight participating hospitals identified 766 cases of dog-bite injuries between June 1, 1995 and August 31, 1996 (Table 1). Although CHIRPP tries to capture data on all injured people reporting to the emergency departments, sometimes that is not possible. As a result, this number does not necessarily represent the total number of dog-bite victims that reported to these hospitals.

Of the 766 identified victims, 248 did not consent to future contact. A further 133 could not be contacted by the CHIRPP coordinator due to an incorrect telephone number, no telephone, or no reply after several attempts. Very few of the patients who were reached refused to take part in the study. In the end, the researchers contacted 385 patients (50.3%) and included their responses in the analysis.

Who?

Patients varied in age from one to 53 years, but 64.7% of the victims were younger than 10. Only 3.9% of the patients were aged 20 or older. Dogs bit slightly more males than females (Table 2).

Which dogs?

The victim knew the dog in 274 of the cases (71.2%) and lived with the dog in 99 of the cases (25.7%). Children were bitten more often by a neighbour's dog than by one owned by their immediate family (parents), while adults were bitten more often by a dog belonging to their immediate family (Figure 1).

Of the 385 records in the study, 278 (72.2%) specified the breed of the dog. There were 50 types of purebreds and 33 types of cross-breeds identified. The most common breeds were German Shepherds (40), Cocker Spaniels (16), Rottweilers (16) and Golden Retrievers (15). Of the 283 cases in which the sex of the dog was known, 72.7% were male. Forty-three dogs (11.2%) had received obedience training and nine (2.3%) had been trained as guard or attack dogs. Most dogs (71.6%) had not previously bitten a person (of the 267 dogs for which this information was available).

When?

Bites were more frequent in the summer and during the evening: 38.0% of the bites took place during June, July and August (proportion adjusted for the 15-month study period); and almost twice as many bites took place between 4:00 and 8:00 p.m. (41.8%) as between noon and 4:00 p.m (21.2%).

Where ?

The bites occurred more often at a home than in a public place. When the person was bitten at his or her own home, the attack usually took place inside (71.6%), but when the person was bitten at another person's home, the attack usually took place outside - on the property, in the yard or in the garage (60.5%). Children younger than four and adults older than 15 were more likely to be bitten at home (Table 3).

Injuries

The dog injured the head and face most often (181, 47.2%), followed by the arm (125, 32.4%), the leg (57, 15%) and the trunk ( 1 9 , 4.9%). There was a clear relationship between age and the body part injured. Of children aged 1-4 years, 74.1% were bitten on the head or face, while only 20.0% of people aged 15 years and older sustained bites to the head or face. Conversely, 68.0% of people aged 15 years and older were bitten on the arm or leg as compared to 25.1% of children aged 1-4 years. This pattern, which has been observed in other studies as well, can be attributed to the fact that a child's head or face is more accessible to dogs than an adult's. Also, situations involving both ordinary and unusual interaction with the animal seemed to result more often in head injuries (56.2%) than did those without interaction (25.4%). Cases involving no interaction (32.7%) produced more leg injuries than did those with interaction (7.7%) .

Circumstances

Researchers assigned each dog-bite injury record to one of three general categories - ordinary interaction, unusual interaction and no interaction - depending on the circumstance leading up to the bite. More than a third of patients (38.5%) reported ordinary interaction with the dog (e.g. petting, feeding or playing), while slightly fewer people (32.7%) reported unusual interaction (e.g. teasing, hurting or taking away food or a toy). Only 28.8% of incidents involved no interaction whatsoever with the dog (e.g. the victim was walking, in-line skating, bicycle riding or delivering newspapers), including 10 cases in which the victim was delivering newspapers or flyers (Figure 2).

The type of interaction prior to the bite varied according to the victim's age: the younger the victim, the higher the proportion of bites due to unusual interaction (Table 4). The results support the argument that young children, because of their lack of judgment or their difficulty in recognizing the dog's warning signs, are more likely to act in ways the dog considers threatening.

Treatment

Less than 10% of patients required hospital admission, 34% were treated and required medical follow-up and 58% were not expected to require medical follow-up. Younger children, especially those aged 1-4 years, were hospitalized more often than people older than 15 (Table 5).

In 73.0% of the 385 cases, emergency room staff simply cleaned and disinfected the wound. Physicians prescribed oral antibiotics for 116 patients (30.1%), applied a dressing with antibiotic ointment for 60 (15.6%), put stitches in 107 (27.8%) and applied steristrips for 34 (8.8%). A total of 55 patients (14.3%) received a tetanus vaccination, but only one (0.3%) received a rabies vaccination. Wound length, which was recorded in the medical file for slightly more than half the patients, ranged from 1 mm to 150 mm; the median length was 10 mm.

Even though the rabies virus can be transmitted through dog bites, 171 (44.4%) of the patients interviewed said they had not monitored the animal's behaviour or health to ensure it was not a rabies carrier. Only 103 respondents (26.8%) reported that they had observed the dog for 10 days following the bite, the period necessary to conclude with certainty whether it was carrying the rabies virus or not. On the other hand, 31 (8.1%) said the animal had been killed, often within 24 hours of the incident (18 times, or 58% of killed dogs). Information was not collected on whether the brains of these dogs were examined for evidence of rabies. In only 104 cases (27%) did the medical file indicate that the patient/parent had been given instructions on how to monitor the animal in the days following the incident; however, it is possible that the physician dispensed this advice without noting it in the file.

Conclusions

On the basis of the study's results, it is clear that the situations in which dog bites occur are, to a point, preventable, because they primarily involve a well-defined group of individuals and a specific environment. These incidents most often involved children younger than 10 years in a familiar environment, along with a known dog without a history of aggressive behaviour. These children were more likely than other victims to have been engaged in unusual interaction with the dog and thus to have provoked an aggressive reaction from the dog. Furthermore, young children are more likely to sustain head and facial injuries and thus to experience long-term, visible sequelae. Lastly, it seems that bite victims or their parents are not sufficiently aware of the risk of rabies transmission. Perhaps discussions between public health officials and emergency room physicians could lead to more complete follow-up with the victims and their families after their emergency room visits.

The CHIRPP database is an important source of information on how various types of injuries occur. In this particular study, the CHIRPP data combined with the data from the telephone interviews provided even more detailed information in an area where there is little documentation: the circumstances surrounding dog bites. Information of this type is needed to develop community action or prevention programs aimed at reducing the incidence of dog bites.

This was the first time that CHIRPP coordinators and Child Injury Division staff conducted a collaborative prospective study in several hospitals. It is hoped that the expertise acquired by all those involved will encourage joint research projects using CHIRPP data in the future.

References

Rosenberg, N.M., L.M. Dos Santos, et al. 1995. Dog bites. Pediatr Emerg Care 11( 5): 313-316.

Sacks, J.J., M.-J. Kresnow, et al. 1996. Dog bites: How big a problem? Inj Prev 2: 52-54.

Sacks, J.J., R. Lockwood, et al. 1996. Fatal dog attacks, 1989-1994. Pediatrics 9 7 ( 6 ) : 891-895.

Sacks, J.J., R.W. Sattin et al. 1989. Dog-bite-related fatalities from 1979 through 1989. JAMA 262(11): 1489-1492.

Acknowledgements

The authors would like to thank all the CHIRPP coordinators who cooperated on the project: Carole Orth (Vancouver), Catherine Morrison (Winnipeg), Alison Morrison (London), Shirley Yee (Toronto), Elizabeth Platonov (Montreal), Glenn Keays (Montreal) and Geneviève Jomphe (Rimouski). Thanks also to Maureen Cullingham, in charge of CHIRPP communications, for the original idea and for her enthusiasm.

The questionnaire used in this study is available upon request. For further information, contact Jasline Flores, Centre de santé publique de Québec, by phone at ( 418) 666-7000 ext. 441, by fax at (418) 666-2776 or by e-mail at jflores@cspq.qc.ca; or Janet Brown, Child Injury Division, by phone at (613) 952-2216, by fax at (613) 941-9927 or by e-mail at janet_brown@hc-sc.gc.ca

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