Assessment of 16-month Sequelae Due to Dog Bites Originally Studied in a French Multicenter Survey from 2009 to 2011

Introduction. Every year in France dog bites lead to several thousand visits to emergency departments and numerous hospital admissions. Objective. This study aims to describe the sequelae 16 months after dog bites. Materials and Methods. Following an initial epidemiological study on the severity of 485 dog bites carried out in 8 hospital emergency departments between May 1, 2009, and June 30, 2010, a second study investigating sequelae 16 months after the bite was conducted among 298 patients between September 2010 and December 2011. Data concerning patients’ sequelae were collected by telephone or email. Results. Almost half of respondents (47%) reported sequelae; of those patients, most of these reports were aesthetic (9/10). There were more sequelae when the bite was located in the head region or the lower limbs. Sequelae were more frequent among women, when the weight of the biting dog was higher, and when the initial severity of the bite was greater. On the other hand, the link between the patient and the dog, the sex of the dog, the type of aggression, and the age of the patient (< 15 years or ≥ 15 years) had no impact on the occurrence of sequelae. One patient in 7 still experienced pain 16 months after the bite; women were more likely to experience pain at that timepoint. No articles on dog bite sequelae were found in the literature. Conclusions. The dissemination of these results among professionals (veterinarians and doctors) and the general population will contribute to making dog owners more aware of the risk of bites and the means of avoiding them.

Both in terms of number and severity, dog bites constitute a little-researched public health problem. In France, 44 deaths were caused by dog bites during the last 30 years; 17 of the deaths were < 5 years old.¹ Studies have shown that dog bites represent several thousand visits to emergency departments each year^2-7 as well as a large number of hospital admissions,^3,7 with an increased number of attacks during the summer.^4,8 The annual incidence of bites requiring medical care has been estimated between 30 and 50 per 100 000 children aged 0 to 15 years⁹ and between 66 and 107 per 100 000 adults.^10-14 For the youngest children (< 4 years), these wounds are more numerous, more serious,¹⁵ and most frequently in the head and neck region,^3,16,17 which may result in physical, aesthetic, or psychological sequelae.¹⁸ In the majority of cases, the person bitten knew the dog and the attack occurred in the home.^2,14 

The size and type of dog have a consequence on the strength of the bite and therefore on its severity.¹⁹ It has not been shown that dogs reputed to be dangerous (attack dogs, guard dogs, etc.) are responsible for a greater number of bites.¹⁵ With children, the age of the patient is a recognized severity factor,^8,20 but the status of the dog in the home also has been recognized.^21,22 Aggressive behavior is often described by ethologists as essentially being of a reactive and relational nature, with the aim of maintaining a certain distance between individuals.²³ The absence of control by the dog on the force of its bite, whether natural in the event of predation or pathological in the case of an intermittent state of anxiety,²⁴ is responsible for bites that are both dramatic and result in serious wounds. It is therefore important to know the circumstances surrounding a dog bite in order to be able to record it as controlled or not. 

An initial study²⁵ of the factors governing the severity of dog bites was carried out in France between May 1, 2009, and June 30, 2010. The population included in this severity study were patients who required treatment by the emergency services following a dog bite in 8 hospitals.²⁶ This study determined factors that affect the severity of dog bites (age and gender of the patient, characteristics of the dog, connection between the dog and the patient, etc.) as well as led to a greater awareness of the aggressiveness of biting dogs and a description of behavior that leads to a dog bite, together with the sequelae 1 month after the bite.²⁵

A second study was carried out with the purpose of describing the number and type of sequelae and disabilities that were the result of the dog bite 16 months after the event. This paper presents the results of this sequelae study. 

This sequelae study addressed those people who had taken part in the first study²⁵ between May 1, 2009, and June 30, 2010, and who had agreed to be contacted again. The study received approval from the French National Commission for Information Technology and Civil Liberties. 

More than 60% of the respondents (298/485) to the first study²⁵ (severity study) also took part in the present study. Chi-square and/or Fisher exact tests were used to compare the characteristics of the 298 respondents and the 187 nonrespondents. Characteristics of the sequelae study respondents were described by age, gender, hospital, and the French profession and social-professional categories (SPC). The injury location and bite severity also were described. The dog breed typology used is the same as that used for the severity study, with the dogs being divided into 10 groups. 

Severity was rated at the emergency department according to the type of injury:

• Severity 1: a scratch or graze, skin not broken;
• Severity 2: a superficial wound (more serious than a scratch or graze) with no other associated injury; and
• Severity 3: a deep wound or a wound associated with other injuries (fracture, damaged tendon, etc.).

For the purpose of analysis, the severity variable was divided into 2 groups: superficial (levels 1 and 2) versus serious (level 3).

The dog bite sequelae were described according to the characteristics of the person bitten, the available medical data, the context in which the attack occurred, and the characteristics of the biting dog. In order to determine the risk factors for sequelae, a descending stepwise logistic regression model was created in which the variables of age and gender of the patient were forced, whatever their significance level. The sequelae in their globality were modelled first, followed by the aesthetic sequelae and disability.

The statistical analysis was carried out using Excel, EPI-Info (Centers for Disease Control and Prevention, Atlanta, GA), and SAS (SAS Institute, Cary, NC) programs.

Sequelae questionnaires were sent to 424 (87%) of the 485 severity study respondents; of these, 298 (70%) were completed.

Compared with those who did not reply, more women (68% vs. 56% for men, P < .01) and children (70% vs. 58% for adults, P = .01) replied to the 16-month sequelae questionnaire. The response rate also varied according to the hospital (P < .01). On the other hand, no difference in response rate was observed in terms of the severity of the bite, the SPC, the connection between the dog and the victim, and the location of the bite. 

Of those who responded, the average age was 28.1 years, with the < 15 years age bracket representing 42% of the sample. There were more female (161, 54%) than male (137, 46%) respondents. The male to female ratio (overall equal to 0.85) did, however, vary according to the age of the victim; it was > 1 for certain age groups, such as 5 to 9 years, 20 to 24 years, and 35 to 39 years. For the ≥ 15 years bracket, the breakdown by SPC suggested manual workers were overrepresented in the sample compared with the French population as a whole. 

Injuries occurred in the upper limbs (142, 48%), the head region (74, 25%), the lower limbs (61, 20%), the abdomen (6, 2%), and the thorax (4, 1%); 9 bite locations were missing. This spread varied according to the age of the victim; children were mostly bitten in the head region (62, 51%) whereas adults were more often bitten on the upper limbs (108, 66%). 

Severity 3 injuries were observed for 47% (140) of bites. Surgery was required as part of medical treatment for 77 (26%) patients, including 41% of serious bites and 12% of superficial bites (P < .01) (Figure 1). Following a bite, 34 patients (11%) were admitted to the hospital, with 21% experiencing a serious bite versus 3% for a superficial bite (P < .01). 

Of the 298 respondents, 265 (89%) considered their health had returned to normal after 16 months, 8 (3%) considered their condition was stable, 20 (7%) considered their condition had improved but had not returned to normal, 3 (1%) considered their condition had deteriorated, and 2 (0.6%) did not know (Figure 2). The health of children < 15 years was more frequently considered to have returned to normal (94%) compared with 85% for adults (P = .04). Similarly, the health of superficial bites was better than serious, 93% versus 84%, respectively (P < .01). 

Since being bitten, 1 in 7 patients (43, 14%) reported experiencing pain. This was more reported by women ≥ 15 years (24, 24%) than 10% of other respondents (P = .01). Patients who experienced a serious bite more frequently complained of pain (34, 24%; P < .01).

In psychological terms, 96 (32%) respondents reported being afraid of dogs after being bitten; this was slightly less frequent (but not significantly so) with children < 15 years (37% vs. 28% of those ≥ 15 years). The morale of 82 patients (27%) was reported to have been affected; this figure was higher for female patients (52, 32%) compared with males (30, 22%; P = .05). However, the morale of those with a serious dog bite had not been affected to a greater extent than those with superficial bites (P = .52). 

Approximately half of the respondents (139, 47%) reported experiencing sequelae linked to the bite. This was more frequent with children < 15 years than with adults (54% vs. 41%, respectively; P = .03). Patients with a serious bite were more likely to experience sequelae (82, 59%; P < .01). Among the reported types of sequelae, the most frequent were aesthetic sequelae (127, 91%), followed by psychological sequelae (22,16%) and functional sequelae (11, 8%). Among those experiencing aesthetic sequelae, 39 (31%) considered this to be handicapping, more so for women than men (31, 46% vs. 8, 13%, respectively; P < .01). 

Following the bite, 55 (18%) patients had to take time off work or school; this percentage was higher for those who suffered a serious bite (26%; P < .01). Injuries caused by the bite required continued medical monitoring for 66 (22%) of respondents. 

The Table presents the final adjustment model for the study of risk factors for sequelae 16 months after the bite. Although age was a significant factor for sequelae in a univariate analysis (children being more at risk), it no longer appears as a risk factor for sequelae after adjusting for other factors. Following adjustment for other risk factors, those with a serious bite experienced sequelae to a significantly higher degree (adjusted odds-ratio [AOR] = 2.75). This also is true for bites in the head region (AOR = 2.41) or lower limbs (AOR = 2.75) and for bites by dogs weighing more than 40 kg (AOR = 3.45). Patients with bites from group 5 dogs (so-called primitive dogs) experienced sequelae more often (AOR = 11.5) than those bitten by group 9 dogs (companion dogs and related breeds). As far as other breed groups are concerned, no significant difference was shown for sequelae 16 months following bite. 

In a similar manner to overall sequelae, aesthetic sequelae are greater for patients with a serious bite (AOR = 3.54), patients with wounds in the head region (AOR = 2.87) or lower limbs (AOR = 2.82), and patients with bites from heavier dogs and by group 5 dogs compared with group 9 dogs (AOR = 11.66) (data not shown). After adjustment for other risk factors, the age and gender of the victim were no longer significantly associated with the appearance of aesthetic sequelae.

The variables associated with the existence of a disability linked to the sequelae (data not shown) were gender (female vs. male; AOR = 2.43; P = .008), bite severity (serious vs. superficial; AOR = 2.57; P = .004), and weight of the dog (> 40 kg; AOR = 3.67; P = .033). The age of the patient, the part of the body affected, the connection between the dog and the patient, the gender and category of the dog, and the type of attack were not associated with the existence of a disability linked to the sequelae.

The majority of the sequelae reported in the present study were aesthetic (127, 91%). There were more sequelae when the bite was to the head or lower limbs, and sequelae were more frequent with women, when the biting dog was heavier, and when the initial severity of the bite was greater. On the other hand, the connection between the victim and the dog, the gender of the dog, the type of attack, the age (< or ≥ 15 years), and the appearance of sequelae were not demonstrated (results not shown). Of the 298 respondents, 43 stated they continued to suffer pain 16 months after the bite. No research with similar outcomes was found in the currently available literature. While adults experienced more serious bites than children, the latter sustained more sequelae; after adjusting for other sequelae risk factors, this result was not confirmed. 

A comparison of the sequelae reported at 1 month²⁵ and at 16 months was carried out. More than one-third of patients (37%) who did not report experiencing sequelae 1 month post bite reported experiencing sequelae 16 months after the bite (data not shown). This confirms the experiences of clinicians who consider it premature to evaluate sequelae 1 month after a dog bite since healing is a slow process that can take several months or even years. 

This study provides a description of sequelae little documented in currently available literature. The majority of studies on dog bites describe the patients bitten (particularly children), the biting dogs, and the circumstances surrounding the bite. The estimations of the incidence of bites are frequently established by age and gender, treatment at an emergency department, hospital admission, and surgeries required, and often grouped together with the risks of infection subsequent to the bite and the measures to be taken to avoid them.^8,28-33 The consequences of the injuries often are considered from the point of view of the treatment, with a description of any surgical revision carried out to improve scars.^33,34 Several works^21,35,36 describe the psychological consequences of being bitten by a dog for children. In a study of 77 children bitten by dogs,³⁵ 42% presented aesthetic and functional sequelae, and 35% experienced psychological disorders, most often when the bite was severe (48%). This was shown by symptoms of anxiety, a state of acute posttraumatic stress, disturbed sleep, and a phobia of dogs or of their own image; 35% of children were afraid of dogs after having been bitten.^35,36 The assessment and treatment of the psychological condition of the child and their family following a dog bite has been the subject of several publications.^21,35,36 

As with the severity study,²⁵ the present sequelae study has not made it possible to distinguish bite characteristics by dog breed. Moreover, the dog breed declared by patients may be inaccurate. The number of respondents was too limited compared with the large number of dog breeds. The authors also would like to note that it has not been possible to obtain reliable statistics on the percentages of the different dog breeds in France.

In other countries the breeds most often quoted as being responsible for serious bites are German shepherds, pit bulls, mongrels, Labrador retrievers, Rottweilers, and bulldogs.^30,37,38 This work underlines the necessity to implement a study based on a large cohort in order to answer the key questions on the incidence of dog bites by breed, based on the categories given in the legislation.

This study may present various elements of bias. On one hand, the severity of the dog bite may be underestimated and children may be more likely to come to the emergency department for less severe injuries (brought by their parents) than adults. On the other hand, adults are more likely to be bitten when trying to separate dogs that are fighting, while children are more likely to be bitten as a warning by the dog (ie, when the dog has been irritated by the child).²⁵ It is therefore possible that, for adults, the control exerted by the dog when biting is less than when it is issuing a warning to children. This may explain the greater severity of injuries suffered by adults,^24,27 with the subsequent effect on the sequelae at 16 months. It should be noted that the study was carried out in only 8 volunteer hospitals²⁵ and therefore is not necessarily representative of France as a whole. The data collection was subject to the bias of declaration: the sequelae and disabilities recorded; their aesthetic, functional, or psychological characteristics have not been confirmed by clinical examination.

Dog bites are a frequent cause of injury; some appear to be severe, leading to disabilities and sequelae, making them a real public health issue all over the world. Moreover, little is known about the sequelae of patients that have been bitten. Media coverage of fatal accidents linked to dog bites in France in the last decade have led to a law aimed at strengthening the protection of people against dangerous animals.³⁹ This law was established on the basis of a genetic model that divided certain dog breeds into the categories of attack or guard dogs, with no foundation based on any epidemiological study. Dog owners and health professionals are relatively unaware of the legislation on dangerous and stray dogs and it is rarely respected. Many dogs bite within their own home environment³⁷; the bite results as extra costs to the owners in terms of having the dog assessed, a feeling of guilt or shame concerning the mayor of their village who will be informed of the dog’s behavior, and the fear of having to put the dog down.

Descriptions of the circumstances surrounding such bites show they very often occur in a context where the dog has not been taken into account: territorial conflict, a sick or stressed animal, an animal that is hungry, etc. A better understanding of dog psychology by dog owners and their friends and family would enable a considerable number of such bites to be avoided. In the United States, an internet tool has been developed that offers a fun way of teaching children (games, video, rewards) how they should behave with a dog.⁴⁰ This tool can contribute to the prevention of dog bites. From an epidemiological point of view, there is a lack of knowledge about dog bite frequency according to dog breed. 

Affiliations: Santé publique France, French National Public Health Agency, Trauma unit, Saint-Maurice, Cedex, France; Centre Hospitalier Annecy Genevois, Pringy Cedex, France; Comportementalist veterinary, Zoopsy, Toulon, France; and DENVF, Zoopsy, La Grabiloné, La Montagne, 05 000 Pelleautier, France

Correspondence: Gaëlle Pédrono, Santé publique France, French National Public Health Agency, Trauma unit, 12 rue du val d’Osne, 94415 Saint-Maurice, Cedex, France; gaelle.pedrono@santepubliquefrance.fr

Disclosure: The study was funded by the French National Public Health Agency.

The authors wish to thank the medical teams who took part in this survey and more particularly Drs Ahlem Benzdira (Le Havre), Valérie Bremond (Marseille), Anne Fontanel (Annecy), Bruno Fremont (Verdun), Jean-Jacques Gozo (Fontainebleau), Philippe Grippon (Fontainebleau), Nicole Hastier (Le Havre), Bernard Longis (Limoges), Véronique Messager (Limoges), Frédérique Molin (Béthune), Souradjou Moussa (Blaye), Nathalie Orsoni (Limoges), and Mrs Natacha Bodiot (Blaye), Michèle Camarca (Marseille), Claudie Delvalle (Blaye), Colette Krier (Verdun), Catherine Mouret (Fontainebleau), Gaëlle Pillaut (Annecy), and Aurore Soulier (Limoges). We also thank the veterinary behaviorists who completed the questionnaires about dogs, including Laurence Dilliere-Lesseur (Le Chesnay), Astrid Dresse (Rosheim), Jean-Marie Hédon (Nérac), Janick Le Dantec (Chateaulin), Nathalie Marlois (Ambérieu en Bugey), Nicolas Massal (Pau), and Gérard Muller (Lille).