A Retrospective Study on Boar-Induced Trauma in 42 Dogs
ABSTRACT
Boar attack–associated trauma (BAAT) in dogs was reviewed by assessing the injury type (blunt, penetrating, or combined), distribution, Animal Trauma Triage (ATT) score, and prognosis. We conducted a university teaching hospital retrospective study of the hospital medical records from December 2013 to January 2024 of all dogs presented for BAAT. Forty-two cases were identified: 36 (85.7%) had blunt trauma, 13 (30.9%) had penetrating trauma, and 7 (16.7%) had combined trauma. The mean ATT score (± standard deviation [SD]) was significantly higher in penetrating (4.3 ± 1.2) and combined trauma (5.0 ± 1.0) than in blunt (2.5 ± 1.3) trauma. Similarly, the mean ATT score was significantly higher in multiple (4.2 ± 1.4) than in single (2.5 ± 1.4) lesions. The mean ATT score was 3.0 (± 1.6) in survivors and 5.5 (± 0.71) in dogs that died naturally. The number of observations was too low to reach statistical significance. The survival rate was 100% (6/6) with only penetrating, 89.7% (26/29) with only blunt, and 85.7% (6/7) with combined lesions. ATT scores were higher in cases that suffered penetrating or combined and multiple injuries. Blunt trauma affecting a single region was more common than penetrating or multiple injuries. The overall survival rate was 90.5%.
Introduction
Wild boars (Sus scrofa) are among the most widely distributed large mammals globally.1,2 In Europe, they are the most common and heavily exploited ungulate species. Their population has significantly increased in recent decades.3 Recreational hunting is the most common method for controlling wild boar numbers in Europe and the primary cause of mortality in this species. This type of hunting includes on-foot hunting, hunting from elevated stands, and drive hunting with dogs.3
Population growth of wild boars across Europe corresponds with a rise in accidents caused by this species,4 including injuries inflicted on domestic animals. The wild boar displays a broad repertoire of defensive behaviors. These include the use of its tusks, which are capable of inflicting deep lacerations, and, less frequently, biting. In addition, wild boars can engage in lateral pushes, using their flanks or shoulders to unbalance or repel an opponent, resulting in blunt trauma.5 Consequently, veterinary clinics in Europe are likely to encounter an increasing number of cases involving domestic carnivores injured by wild boars. To the authors’ knowledge, there are no data reporting the frequency of injuries caused by wild boars to domestic animals (cats, dogs, livestock). Regarding the distribution of the wild boar population in Europe, the density ranges from 0.18 to 74.29 individuals/km² in 2022.6
Trauma is a common cause of death in dogs. It is often described as blunt, penetrating, or both. The most frequent causes are road traffic accidents and animal bites. The survival rate is high for dogs that have suffered trauma, ranging from 88 to 91%.7–9
Scientific data on the type, distribution, and prognosis of injuries caused by wild boars are limited. To our knowledge, only one scientific article has specifically addressed boar attack–associated trauma (BAAT) in veterinary medicine. In this article, the survival rate of the dogs was 91%, and all fatalities had thoracic injuries. Dogs most commonly presented injuries in a single region, and the most commonly affected areas were the thorax, hind limb extremity, and abdomen.10 In addition, the severity of the lesions is classified according to the Animal Trauma Triage (ATT) score, which is designed to predict outcomes in veterinary trauma patients and has demonstrated its effectiveness in predicting animal nonsurvival,11–13 in comparison with the injury severity scoring system, which is commonly used in human victims of motor vehicle accidents.14
The aim of this article was to retrospectively study BAAT in dogs by examining injury types (blunt, penetrating, combined), their distribution, ATT scores, and prognosis. We hypothesized that penetrating and combined traumas, particularly with thoracic involvement, would be associated with a poorer prognosis compared with blunt or isolated injuries.
Materials and Methods
Enrollment
This retrospective study was conducted using data from the University Veterinary Clinic for Companion Animals in Liège, gathered through the electronic clinical database. We identified cases using the keywords “wild boar” and “hunting.” The study included dogs presented to the emergency or surgical departments (orthopedics and soft tissue) from December 2013 to January 2024.
To be included in the study, each case had to have a complete medical record at admission, including details on signalment, clinical examination findings, a detailed list of injuries, injury location, and outcome. All clinical examination findings were required to cover every parameter listed by the ATT score, namely, perfusion parameters (mucous membrane color, capillary refill time, pulse quality, and temperature), cardiac parameters (heart rate and presence of sinus rhythm), respiratory parameters (respiratory rate and presence of distress), description of lesions on the skin, eyes, and muscles (including extent and depth), description of fractures (number and location), and finally, the neurological status of the animal. All these data were collected by several veterinarians, 22 in total, who were specialists-in-training, either in surgery or in emergency and critical care, at the time of the animal’s admission. Dogs were excluded if any of these details were missing or if the cause of the injuries was not clearly established.
Informed consent was not obtained from the pet owners due to the retrospective nature of this study.
Sample Analysis
Three categories of trauma have been created and described as corresponding to distinct groups: blunt, penetrating, and combined injuries. To analyze the distribution of injuries, the body was divided into seven areas: head, neck, thorax, abdomen, pelvis, forelimb, and hindlimb. These regions were chosen to cover all areas of the body, similar to the study by Ko et al., to facilitate comparison of results. Injury severity was assessed using the ATT score (Supplementary Table 1), which has previously been described to be associated with survival in trauma patients.11–13
Statistical Analysis
Categorical variables were described using frequency tables (number and percent) and continuous variables were described using mean and standard deviation (± SD), median and interquartile range (Q1–Q3), and extreme values (Min; Max). Comparisons of ATT scores in function of trauma characteristics were conducted using analysis of variance. Survival was analyzed using a simple logistic regression model on the risk of death. Results were presented as odd ratios and their 95% confidence intervals with associated P values. Calculations were conducted using SAS (version 9.4) software.
Results
Population
A total of 42 dogs met the study inclusion criteria. Of these, 21/42 were female, of which 17 (81%) were intact, and 21/42 were male, of which 16 (76%) were intact. The proportion of intact individuals is similar in males and females (P = .93). The median age and weight of this population were 4 yr (range: 0.5–12 yr) and 16.75 kg (range: 3.5–50.5 kg), respectively. The most represented breeds included crossbred dogs (7/42), hunting terrier (6/42), Jack Russell terrier (5/42), Drahthaar (5/42), and Munster spaniel (4/42).
Types and Distribution of Injuries
In our study population, 36/42 dogs had blunt injuries, 13/42 had penetrating injuries, and 7/42 of had combined injuries (Supplementary Table 2). Twenty-six dogs had injuries in a single region, most often the hindlimbs (10/26). The most common locations were the thorax, hindlimbs, head, and forelimbs (Supplementary Table 3). Thoracic injuries were associated with pneumothorax (9 cases), pulmonary contusions (7 cases), pyothorax (4 cases), rib fractures (3 cases), and superficial wounds (3 cases). All 7 dogs with abdominal injuries also had thoracic injuries. Among them, all injuries were either penetrating (2/7) or both penetrating and blunt (5/7).
Injury Severity
Injury severity was categorized using the ATT score, which ranged from 1 to 6, out of a maximum possible score of 18. The mean ATT score (± SD) in our study was 3.2 (± 1.6) and the median ATT score observed was 3 (range: 2–4).
The mean ATT score (± SD) was significantly higher (P < .0001) in penetrating 4.3 (± 1.2) and combined 5.0 (± 1.0) trauma compared with blunt 2.5 (± 1.3) trauma (Figure 1). Similarly, the mean ATT score (± SD) was significantly higher (P = .0003) in multiple 4.2 (± 1.4) than in single 2.5 (± 1.4) injuries (Figure 2). The mean ATT score (± SD) was 3.0 (± 1.6) in survivors, 5.5 (± 0.71) in dogs that died naturally, and 4.8 (± 1.3) in all dogs that died. The number of observations was too low to reach statistical significance in the study of the impact of the characteristics on the survival (Figure 3).
Citation: Journal of the American Animal Hospital Association 61, 6; 10.5326/JAAHA-MS-7502
Citation: Journal of the American Animal Hospital Association 61, 6; 10.5326/JAAHA-MS-7502
Citation: Journal of the American Animal Hospital Association 61, 6; 10.5326/JAAHA-MS-7502
The survival rate was 100% (6/6) for penetrating injuries, 89.7% (26/29) for blunt injuries, and 85.7% (6/7) for combined injuries, with a 96.2% (25/26) survival rate for single injuries and 81.3% (13/16) for multiple injuries. Overall survival rate was 90.5% (38/42). Two patients were euthanized and 2 died naturally. The four dogs that died had thoracic injuries, with euthanasia due to severe pulmonary contusions (2), fatal pulmonary contusions (1), and postoperative arrest in a case with pyothorax and pneumothorax (1). Of the four deceased animals, two had an ATT score of 5, one had a score of 6, and the last had a score of 3.
Some dogs with penetrating or blunt and penetrating, thoracic and/or abdominal lesions underwent surgical procedures, namely, sternotomy (partial pulmonary lobectomy [1], pneumonectomy [1]), thoracotomy, and exploratory laparotomy (herniorrhaphy [3], gastrotomy [2]). These patients had ATT scores considered high in our study, that is, from 4 to 6 (Supplementary Table 4).
Antibiograms and Cultures
Among all the patients, 34/42 (80.9%) received antibiotic therapy. Amoxicillin-clavulanic acid was the most frequently used antibiotic (33/34), with cephalexin used only once. Four dogs underwent triple antibiotic therapy consisting of amoxicillin-clavulanic acid, enrofloxacin (3) or marbofloxacin (1), and metronidazole. Cultures and antibiograms were performed for three of these dogs, and the antibiotic therapy was adjusted in two of these cases. Two dogs received dual antibiotic therapy, and cultures and antibiograms were conducted for both, with the therapy being adjusted in one case.
Samples for antibiograms and cultures were taken in 9/42 of cases. Ten lesions were sampled in total, 6/10 from wounds and 4/10 during surgery after thoracic or abdominal lavage. Samples from wounds, namely, open fractures or dehiscence, were positive in 5/6 cases. Isolated bacteria were common bacteria found in the environment or commensal bacteria from boars (Hafnia alvei, Morganella morganii, Yersinia enterocolitica, Staphylococcus pseudintermedius, and Proteus mirabilis). All four samples collected in surgery after lavage yielded negative cultures. All these dogs were discharged from the hospital.
Discussion
This is the first study on boar-induced trauma that describes injury types (blunt, penetrating, combined), their distribution, their severity based on ATT score, and their prognosis, in a dog cohort in Europe.
The majority of patients in this retrospective study were hunting breeds, with a median age of 4 yr (0.5–12), and as many females as males were represented. These findings are consistent with our expectations that most dogs attacked by boars were engaging in wild boar hunting activities. The population of intact dogs is more represented than that of neutered ones, but this proportion is similar between males and females.
In the article by Ko et al., the population consisted predominantly of male dogs (88%), and all individuals were intact.10 The predominance of intact animals in these studies may be linked to behavioral traits desirable for hunting. Intact males have been demonstrated to exhibit significantly greater boldness compared with neutered males and females, a trait sought after in hunting dogs.15 Conversely, neutered males are more prone to stress, and display insecurity, which are less desirable characteristics in a hunting context.15,16
Blunt trauma was the most common type of injury, such as pulmonary contusions, skin wounds, or fractures for example. Blunt trauma affecting a single region was more common than penetrating or multiple injuries. The thoracic region was the most frequently injured region. When only one area was affected, the hindlimbs were most often injured, which could suggest the dogs were trying to avoid trauma. These results are consistent with previous literature, in which blunt trauma also was the predominant type of injury sustained by hunting dogs, often affecting a single anatomical region, with the thorax and hindlimbs as the most common sites of injury.10
Animal Trauma Triage score was chosen in this article for several reasons. First, this score was designed to predict outcomes in veterinary trauma patients and has demonstrated its effectiveness in predicting animal nonsurvival.11–13 Second, this score is calculated on the basis of six major categories, frequently assessed on admission, particularly during trauma, namely, perfusion parameters (color of mucous membranes, capillary refill time, quality of pulse, and temperature), cardiac parameters (frequency and sinus rhythm or not), respiratory parameters (frequency and respiratory distress or not), description of lesions on integument, eye, muscle (extent, depth), description of fractures (number, location), and, finally, the neurological state of the animal. A score from 0 (= little) to 3 (= severe) is assigned to each of these categories, with a possible total of 18 (Supplementary Table 3).
Our study indicated that ATT scores were higher in cases that suffered penetrating or combined and multiple injuries. These results correspond to our hypotheses at the beginning of this study and were expected given that penetrating lesions are described in the ATT score and associated with the highest score in the corresponding category. The severity of lesions according to the ATT score in our study seems relatively mild overall, with the median prevalence being 3 out of 18. In the Korean study by Ko et al., lesion severity was classified using the Injury Severity Score, with a score of 2 out of 6 being the most frequently observed, corresponding to moderate severity.10
Mean ATT score was significantly higher in multiple (4.2) than in single lesions (2.5). When the injury severity was low (ATT score of 1 or 2), the injuries were predominantly confined to a single area of the body and rarely involved thoracic trauma. In dogs with higher ATT scores (5 or 6), the injuries typically involved multiple areas, with frequent involvement of the thorax and abdomen. All of these results confirm our hypotheses. These results are also consistent with those reported in the study by Ko et al., where an Injury Severity Score of 4–6, indicating a life-threatening condition, was most frequently observed in cases involving thoracic lesions, followed by abdominal injuries.10
In addition, ATT score was correlated with prognosis. Indeed, the mean ATT score was 3.0 in survivors compared with 4.8 in dogs that died. Other studies have similarly identified a decreased prognosis with increasing ATT score.11,17,18 The original article describing the ATT score, by Rockar et al., has shown that each point increase in this score results in a 2.3–2.6 times decreased likelihood of survival, in a population of dogs and cats that had undergone trauma. Within this cohort, motor vehicle trauma was the most represented, followed by animal interaction.18 In the study written by Hall et al,12 which included a population of 315 dogs that had experienced trauma, blunt trauma was the most common type, followed by penetrating trauma. Motor vehicle accidents and bite wounds were the primary causes of blunt and penetrating trauma, respectively. This study demonstrated that, within its population, an ATT score ≥5 had a sensitivity of 83% and a specificity of 91% for predicting nonsurvival in dogs. The overall survival rate was 91%, which is similar to the results observed in our study. Moreover, as in our study, penetrating trauma had a higher survival rate than blunt trauma, which is in contrast with another study.9 The authors also noted that surgical interventions were associated with survival. However, because this study did not provide a description of the lesions, drawing definitive conclusions remains challenging.
In our population, one-third of the patients with thoracic injuries underwent surgical procedures such as sternotomy or thoracotomy. Among these dogs, only one did not survive. This observation may be a result of the lack of a surgical solution (e.g., in cases of contusions) being associated with a poorer prognosis or may suggest a greater commitment from owners whose dogs underwent surgery.
The overall survival rate of dogs with BAAT was 90.5%. Studies have indeed demonstrated that dogs suffering blunt trauma have a favorable prognosis.9 Dogs that died had suffered thoracic injuries, and the overall survival rate for dogs with thoracic injuries was 72.2%. All dogs that had abdominal injuries had concurrent thoracic injuries. The survival of dogs with abdominal injuries was 85.7%, and abdominal injuries in addition to thoracic injuries did not seem to worsen prognosis. Three of the deceased dogs had pulmonary contusions. These results seem to closely parallel those of the Korean study by Ko et al., which reported a survival rate of 91%, with all dogs that died having thoracic injuries.10
Pulmonary contusions occur as a result of a compression-decompression injury to the thoracic wall. Owing to the flexibility and resilience of the canine rib cage, much of the impact energy is absorbed, often leading to significant internal thoracic injuries without obvious external signs. The sudden change in intrathoracic pressure causes alveolar and capillary rupture, resulting in blood filling the alveolar spaces. Additionally, shear forces damage the pulmonary vascular endothelium, increasing vascular permeability and contributing to further interstitial and alveolar edema. This combination of alveolar hemorrhage and pulmonary edema impairs gas exchange, leading to hypoxemia, which clinically presents as tachypnea and dyspnea in affected dogs.19 There is limited information on the survival rate of dogs with pulmonary contusions. The article by Campbell et al. reports a survival rate of 30% among dogs with pulmonary contusions that underwent mechanical ventilation.20 In contrast, Powell et al. report a more favorable outcome, with only a 7% mortality rate in dogs presenting with pulmonary contusions following motor vehicle trauma.19 The reported prognosis varies considerably between studies. The study by Campbell et al. presents a selection bias, as it only included dogs that required mechanical ventilation, representing the most severely affected cases. In contrast, the study by Powell et al. included all dogs with pulmonary contusions following motor vehicle accidents, regardless of severity. This broader inclusion of both mild and severe cases may explain the more favorable prognosis observed in this more heterogeneous population.
Road traffic accidents are one of the most common causes of blunt trauma in dogs8,13 and were responsible for approximately 1.2 million human deaths in 2021, according to the World Health Organization. Given their significant impact, several studies have focused on these populations, and results indicate that survival rates in dogs are high, ranging from 88 to 91%7–9,12,13,21 Young individuals (younger than 3 yr) appear to be the most affected among both dogs8,9,21 and humans.22 Thoracic injuries are a major cause of mortality in both, following trauma.9,19,23 To date, no gender predisposition has been clearly established.8 These findings align with those observed in our study population. Populations having suffered road accidents as well as those having been attacked by wild boars therefore seem rather similar.
Antibiograms and cultures were only performed on nine patients and were all positive. The isolated bacteria were common environmental bacteria or commensal bacteria from boars (Hafnia alvei, Morganella morganii, Yersinia enterocolitica, Staphylococcus pseudintermedius, Proteus mirabilis).24–29 Confirmed infection did not negatively affect outcome as all dogs survived until discharge. When dual or triple antibiotic therapy was implemented, a culture was performed in the majority of cases, that is, 83.3%. Cultures and sensitivity testing resulted in treatment changes in three cases. Therefore, it can be noted that wounds caused by wild boars are frequently infected, as expected. However, by following general recommendations for the management of contaminated wounds, including thorough cleaning, performing bacterial cultures, and adjusting treatment as needed, a favorable outcome can usually be achieved.
Our study has several limitations, which are mostly attributable to its retrospective nature. Indeed, the ATT scores were established retrospectively from medical records, which may represent a limitation, particularly because of potentially missing or insufficiently detailed data. Although animals that did not meet all the ATT score criteria were excluded, the completeness and accuracy of the available information may vary. Moreover, clinical examinations at admission were not always performed by the same veterinarians, which could lead to interobserver variability and thus influence the scoring of clinical criteria. Furthermore, the rather small cohort experiencing a mostly favorable outcome resulted in a low number of fatalities, which prevented establishing an association between the type, number, or distribution of injuries and prognosis.
Conclusion
This study found a high survival rate (90.5%) for dogs with BAAT, which can reassure veterinarians and owners upon admission of dogs with extensive trauma following BAAT. Penetrating and combined traumas were associated with higher ATT scores, indicating higher severity, and thoracic injuries showed an association with mortality. Prospective studies in larger cohorts may focus further on the impact of injury type and ATT scores on survival outcome to better understand their influence on prognosis.
Distribution of the ATT scores among different types of injuries. Boxplots illustrating the distribution of the ATT scores among different types of traumas (blunt, penetrating, or both). P value analysis of variance were calculated between blunt trauma versus penetrating trauma and blunt trauma versus combined trauma. The mean ATT score (± standard deviation) is significantly higher (P < .0001) in penetrating 4.3 (± 1.2) and combined 5.0 (± 1.0) trauma compared with blunt 2.5 (± 1.3). All ATT scores were obtained retrospectively. ATT, Animal Trauma Triage.
Distribution of the ATT scores based on the distribution of injuries. Boxplots illustrating the distribution of the ATT based on the distribution of injuries (single and multiple). P value analysis of variance was calculated between single and multiples injuries. The mean ATT score (± standard deviation) is significantly higher (P = .0003) in multiple 4.2 (± 1.4) than in single 2.5 (± 1.4) injuries. All ATT scores were obtained retrospectively. ATT, Animal Trauma Triage.
Distribution of the ATT scores in survivors and deceased dogs. Boxplots illustrating the distribution of the ATT in survivors and deceased dogs (euthanized and natural death). P value analysis of variance was calculated between survivors and all deceased dogs. The mean ATT score (± standard deviation) was 3.0 (± 1.6) in survivors and 4.8 (± 1.3) in all dogs that died. The number of observations was too low to reach statistical significance in the study of the impact of the characteristics on survival. All ATT scores were obtained retrospectively. ATT, Animal Trauma Triage.
Contributor Notes
The online version of this article (available at www.jaaha.org) contains supplementary data in the form of four tables.
