Introduction

Canine practitioners, through the course of their career, can expect to face a multitude of long bone fractures of various configurations in a plethora of breeds. Considering long bone fractures being the most common orthopaedic condition encountered; regional practitioners need to be equipped, informed and capable of handling them efficiently. The occurrence and the pattern of fracture in dogs have been described previously by Aithal and Singh (1999), Raghunath et al. (2007) and Kumar et al. (2013). However, the association of different factors in the occurrence of long bone fractures has not been considered. Also, the data on technique of repair and the associated short term and long term outcome of the repair is scarce. In a study, Dvorak et al. (2000) has evaluated the postoperative outcome of fractures of long bones repaired by internal fixation techniques alone and the complications were graded as major and minor. On the other hand, fractures that underwent alternative mode of treatments including external skeletal fixation (ESF) and external coaptation also need to be evaluated postoperatively. In addition, the extent of association of various factors in the postoperative outcome of fracture repair requires inspection. The goal of the present study was not only to detect the occurrence of long bone fractures in the study population, but also to investigate the possible relations between the various factors like etiology, age, breed, gender, season, bone involved, side affected, nature of fracture, location and orientation of fracture, time lapse in presentation, technique of repair and how they affected the outcome.

Materials and Methods

Long bone fractures in 216 dogs presented for treatment at Referral Veterinary Polyclinic, from June 2015 to May 2016 were analyzed based on client survey, observations, clinical records, survey radiographs and sequential follow up radiographs. Clients were surveyed regarding the time lapse between fracture occurrence and presentation, the cause of fracture and the age of the animal. The month and season of presentation were noted. Observations regarding the breed of the dog, gender, affected side, nature and type of the fracture, and the bone affected were noted. Systematic evaluation of survey radiographs was done to pinpoint the precise fracture configuration. Radiographs were then utilized to assign an Unger’s class based on the Unger system of classification (Unger et al., 1990).  The chosen modality and technique for fixation used for each particular case were recorded. Sequential follow up clinical evaluations and radiographs were used to investigate the outcome in terms of complications. Minor and major complications were recorded as defined by Dvorak et al. (2000). Slight misalignments, hypertrophic callus, mild arthrosis and delayed union were recorded as minor complications; while, severe arthrosis, non-union, osteomyelitis and implant failure were recorded as major complications.

Statistical Analysis

Frequency data collected was then expressed as percentage of the total long bone fractures. Statistical associations between the various recorded factors were analyzed using Chi-square test at a confidence level of 95%. Subsequently, frequencies with adjusted residuals with a value of 1.96 or greater, or –1.96 or less, were considered significant at a 95% level of confidence (Everitt, 1980).

Results and Discussion

A total of 216 canine long bone fractures were recorded during the period from June 2015 to May 2016. Previously, a study by Kumar et al. (2013) at the same locality reported 691 cases of canine long bone fractures over a period of six years. Hence, it should be assumed that the population of dogs is increasing. Also, the dog owners do care the pets and are aware of the veterinary services available.

Age

The age of dogs presented was 19.90 ± 1.68 (Mean ± SE) months, ranging from 1 month to 16 years. The highest number of cases was reported in dogs less than six months (41.2%, 89) of age followed by the age group of 6-12 months (18.5%, 40), 1-2 years (17.1%, 37) and more than 3 years (17.1%, 37). Young growing dogs were prone to multiple fractures. Inherent weakness of bone in their growing stage with a premature skeleton was the predisposing cause of fracture as observed by Kumar et al. (2007). Furthermore, young animals are still precocious and inexperienced especially around automobiles and with heights, two of the leading causes of fracture. There was a significant association between age group and bone affected (p<0.05) as shown in Table 1.

Table 1: Age wise occurrence of fractures in various bones

In most of the skeletally immature dogs less than 6 months of age, the bones were osteopenic characterized by reduced cortical radiographic density (p<0.05).  This may be factored by the multiple trauma, automobile accidents and their immature skeletal system, compounded by improper dietary supplementation of vitamins and minerals leading to multiple fractures. There was no significant relationship of age group with different parameters hypothesized except bone affected, nature of fracture and rate of complication.

Breed

Highest frequency of cases presented were of non-descript (41.7%) followed by Indian Spitz (21.3%), German shepherd (13%) and Labrador Retrievers (11.1%). Among the thirteen different breeds of dogs affected, more representation of Indian Spitz and Non-descript dogs was dependent on the popularity of these breeds in this particular locality. Also, it is thought that Indian Spitz and non-descript dogs are allowed free roaming and hence are prone to injury (Aithal et al., 1999). A study in a different locality by Ramesh (2011) also reported Non-descript as the highest breed presented followed by Indian Spitz. However, there was no significant relationship of the breed with other parameters hypothesized.

Sex

Male dogs were the majority presented with fractures (60.6%, 131). Higher male pet dog population owing to the socioeconomic factors of female dog fecundity and the straying nature of males may be the factors that led to increased incidence of fractures (Aithal et al., 1999). There was no significant relationship of gender with other parameters hypothesized.

Etiology

The leading cause of fracture of long bones in the present study was automobile accidents (43.1%, 93) followed by fall from a height (36.6%, 79) as reported previously by Balagopalan et al. (1995), Aithal and Singh (1999) and Harasen (2003). Other causes were abuse or malicious injuries (8.3%, 18) and dog fights (6.5%, 12). The high vehicular flow in the city and the housing conditions in the locality may be a major reason for this, with a tendency for active territorial male dogs to jump from heights while chasing monkeys. An alarming number of fractures due to abuse or malicious injury also indicate mistreatment of animals (Surbhi, 2011).

Season

The highest number of canine long bone fractures were presented in the month of July (12.5%) followed by March (11.1%), February (10.2%) and September (9.7%). There were only marginal differences in the number of cases presented during summer and monsoon. Least number of cases (31%, 67) was presented during the winter (November to February). The lower frequency in winter could be due to the reluctance of the client to present the case at the referral centre owing to the harsh climatic conditions in this region. Sedentary behaviour of dogs during winter is an alternate hypothesis for decreased occurrence of fractures (Minar et al., 2013). There was no significant relationship of season with other parameters hypothesized except minor complication rate.

Side Affected

The left limb (49.1%, 106) was affected in marginally more cases than the right limb (47.2%, 102). Bilateral fractures were seen only in 3.7% of the recorded cases. Affection of right limb more than the left as reported by Rani et al. (2004) was in contrast to our findings.

Time Lapse

The time lapse between fracture occurrence and presentation was 3.12 ± 0.62 days (Mean ± SE). A vast majority of cases (62.5%, 135) were presented early (less than 2 days after injury), 18.5% of cases were delayed (2 to 4 days after injury), 13.9% were presented late (4 to 8 days after injury) while 5.1% of cases were excessively delayed (beyond 8 days after injury). Early presentation indicates prompt response by the clients. Yet, the fact that the mean time of presentation was above 3 days, indicated that the remaining cases were delayed sufficiently enough to raise the mean level. In a study by Dvorak et al. (2000) on complications of long bone fractures in dogs, a mean time lapse of 5.04 days had a significant impact on the postoperative outcome. Contrary to that report, no association between the time lapse and outcome was found in the present study.

Bone Affected

In the present study, the femur (37%, 80) followed by radius-ulna (28.7%, 62) and tibia-fibula (20.4%, 44) were the most frequently affected long bone and humerus (7.9%, 17), the least affected as reported previously in many studies (Harasen, 2003; Beale, 2004; Kumar et al., 2013). Biomechanically, femur is positioned in such a way that it is vulnerable to physical trauma (Smith, 1985; Ramesh, 2011). In contrast to our findings, radius-ulna has been reported to be the most commonly fractured bone by Dvorak et al. (2000). Multiple bone fractures were seen only in 6% of the presented fracture cases.

Nature of Fracture

Compound (open) fractures occurred only in 10.2% (n=22) of cases. There was a significant association between age group and the occurrence of compound fractures (p<0.05). There was a high frequency of compound fractures in dogs above 3 years of age and low in dogs less than six months of age. In retrospective studies over a period of six years by Aithal and Singh (1999) and Kumar et al. (2013), the type of canine appendicular fractures did not vary significantly with age group. This was in contradiction to our findings. A statistically significant (p<0.05) association was also found between the bone affected and the nature of fracture. Higher number of tibia fractures was compound in nature. This may be due to the low amount of soft tissue covering over the medial surface of the bone, and the distal positioning of the bone. Compound fractures of the proximal bones, femur and humerus, were not recorded; owing to the vast muscular covering over these bones. Also, Dvorak et al. (2000) have reported that compound fractures occurred only in bones distal to the stifle or elbow.

Orientation and Position of Fracture

Transverse fractures were the most frequently observed orientation (49.5%, 107) in this study followed by short oblique (28.7%, 62), comminuted (16.7%, 36) and long oblique (3.7%, 8) fractures as reported in previous studies (Harasen, 2003 and Kumar et al., 2007). Based on the position of the fracture on the bone, a majority of fractures occurred in the mid diaphyseal region (51.9%, 112), followed by fractures of the distal diaphysis (24.5%, 53), distal epiphyses (12%, 26), proximal diaphysis (7.9%, 17) and the proximal epiphysis (3.7%, 8) as observed by Raghunath et al. (2007) and Ramesh (2011). Kumar et al. (2007) differed by saying it is equally distributed over the entire length of the bone. The distribution of different orientation and position of fractures in each bone is shown in Table 2.

Table 2: Bone wise distribution of different fracture types within each long bone region

In femur, comminuted fractures were seen more in number, as compared to other bones. However, transverse fractures predominated in all the bones followed by short oblique and comminuted fractures. Spiral fractures were seen only in humerus, may be due to its shape and muscular attachments (Nortjeac et al., 2015).

Unger’s Classification

Based on Unger’s classification, maximum number of fractures (18.5%) were of type 22 A2 which represented distal zone, diaphyseal radius-ulna fractures followed by 32 A3 (14.8%) and 32 A2 (7.9%), which represented diaphyseal transverse and oblique fractures of femur respectively. Even though femur was the most commonly affected bone, the 22 A2 was the class frequently encountered because the exact fracture orientation and position occurred most frequently in radius-ulna; whereas, the fractures were of varied types in femur. Transverse and oblique diaphyseal fractures of tibia-fibula, 42 A3 and 42 A2, were seen in 7.4% and 6.9% of the cases, respectively. The three most common fracture classes, 22A, 32A and 42A, which were reported earlier by Miller et al. (1998), mirrored the findings of the present study.

Mode of Treatment

Internal fixation was the modality used in majority of cases (52.8%, 114), which is in accordance with the fact that femur fractures represented the highest number of cases and also due to the referral nature of the institute. This was followed by coaptation/movement restriction (35.6%, 77) and ESF (6.9%, 15). Intramedullary pin (IMP) or cross IMP was used for highest number of cases (34.3%, 74). Plaster of Paris or fiberglass casts (23.1%, 50) and bone plating (17.6%, 38) were two other frequently used treatment modalities. An obvious significant (p<0.05) relationship exists between the bone fractured and the technique applied. In femur and humerus, internal fixation by IMP and bone plates was used more frequently, while coaptation and ESF was used in low frequency. Coaptation by splints and casts was mainly utilized in fixation of fractured radius-ulna which contributed to the finding that coaptation was the second most commonly employed modality owing to repair of second most frequently fractured bone. This was followed by more frequent use of ESF while internal fixation was rarely used. For fractures of tibia-fibula, external fixators were used in more number than coaptation. The treatment chosen was significantly (p<0.05) related to the simple or compound nature of the fracture. ESF and amputation were performed in a statistically significant (p<0.05) number of compound fractures; while other techniques were significantly (p<0.05) used in low frequency. In lieu with the finding that compound fractures were seen in higher frequency in tibia-fibula, it is reasonable that a statistically significant number of tibial fractures were fixed by ESF or splinting. Even amputation was considered in considerable number of compound fractures that failed with ESF.

Outcome of Treatment

Minor and major complications were seen in 9.7% and 12% of recorded cases respectively similar to those reported by Dvorak et al. (2000) and Kumar et al. (2013) in mixed clinical settings. Due to the referral nature of the polyclinic, no follow up was seen in 13% of cases. Major complications were seen after fixation of 9.3% of transverse fractures and 11.3% of short oblique fractures. A significant (p<0.05) relationship exists between age group and outcome. More percentage of major complications was recorded in the age group between 2 to 3 years followed by the age group above 3 years, probably due to the slower bone healing rate in mature animals in comparison to young puppies. A low frequency of major complications was seen in puppies below 6 months of age. There was a significant (p<0.05) association between bone affected and the rate complications. The frequency of major and minor complications encountered with the use of different techniques in each bone is shown in Fig. 1.

Fig 1: Bone wise distribution of complications associated with each technique

The rate of major complications was also significantly (p<0.05) related to the treatment adopted. A significantly high frequency (p<0.05) of major complications occurred after ESF, probably stemming from the fact that this technique was most commonly used in compound fractures, which themselves were liable to major complications. The complication rate was significantly (p<0.05) associated with the nature of fracture. Major complications occurred in a significantly (p<0.05) high frequency in compound fractures. A significant association between compound fractures and poor outcome has been reported previously by Dvorak et al. (2000). There was a significant (p<0.05) association between season and frequency of minor complications. A low percentage of minor complications occurred in dry summer season and a high percentage in monsoon (non-significant) that was probably impacted by the occurrence of fewer incision infections in summer compared to monsoon. No such pattern was noticed among major complications.

The present study lacks investigation on the nutritional and metabolic factors involved in the aetio-pathogenesis of fractures. Also, it was unfortunate that minimally invasive biological internal fixation technique like interlocking nail and plate-rod constructs have not been used in fixation of any of fractures.

Conclusion

Significant relations between various factors in the occurrence and outcome of repair of long bone fractures in dogs have been identified. Hence the mode of fracture treatment may be promptly selected considering the factors affecting the outcome of repair.

Acknowledgement

The authors thank Director, ICAR-Indian Veterinary Research Institute, Izatnagar for providing necessary facilities for the study.

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