A survey of injuries at five greyhound racing tracks

Characteristics, surgical treatment, and outcomes of injuries involving the tarsus in greyhounds

Objective

The first objective of this study was to describe the type of tarsal injuries sustained, surgery performed, and postoperative complications in greyhounds presenting to a single veterinary hospital. An additional objective of the study was to determine the surgical site infection (SSI) and explantation rate, and if any variables were associated with an increased risk of SSI and/or explantation.

Animals

116 greyhounds receiving surgical intervention for a tarsal injury.

Proceures

Medical records from a single veterinary referral hospital were reviewed retrospectively. Data retrieved included signalment, details regarding the injury, surgical intervention, concurrent castration, surgical/anesthesia times, postoperative management, time to healing, and postoperative complications. In cases that underwent explantation, cause, time from initial surgery, and risk factors were evaluated.

Results

The most frequently diagnosed tarsal injuries were fracture of the central tarsal bone (CTB; 57.8%), calcaneal fracture (56.9%) and proximal intertarsal subluxation (34.5%). The most common injury combination was a CTB fracture with a calcaneal fracture (31.9%). In total 115 (99.1%) survived to discharge. Of these, 46 (40.0%) were diagnosed with an SSI and 59 (51.3%) underwent explantation. The most common indication for explantation was SSI. Concurrent medial and lateral surgical approaches was found to be associated with an increased likelihood of SSI and explantation.

Clinical relevance

Practitioners performing surgical intervention for tarsal injuries in greyhounds should be aware of the high SSI rate and likelihood that explantation will be required. This risk is elevated for injuries requiring a bilateral surgical approach.

Injury Risk Factors Associated with Training and Competition in Flyball Dogs

Flyball is a fast-paced, high-energy canine sport which has received negative press regarding the potential for injury, and possible welfare implications for canine competitors. Whilst frequency of injury within the sport has been investigated, evidence gaps remain regarding cause. The aim of this study was therefore to identify risk factors for injury within the sport, with a view to improving competitor safety. An online questionnaire was used to obtain data on dogs that had competed in flyball in the last five years but remained injury free, and a second questionnaire obtained data on dogs that had also competed within the last five years but sustained an injury. Data relating to conformation and performance was collected for 581 dogs, with the same data plus information relating to injury collected from an additional 75 injured dogs. Data were then compared using univariable, multivariable and multinomial logistic regression. Dogs completing a flyball course in less than four seconds had the highest level of injury risk (p=0.029), which reduced as time taken increased. There was an association between risk of injury and increasing age, with dogs over 10 years old most likely to be injured during their career in the sport (p=0.004). Furthermore, dogs using an angle of flyball box of between 45° and 55° had a greater risk of injury, while using an angle between 66° and 75° reduced the risk of injury by 67.2% (OR: 0.328). Use of carpal bandaging was significantly associated with carpal injuries (p=0.042). These findings identify new risk factors for injury within flyball which can be used to improve welfare and safety for competitors.

Management of Injuries in Agility Dogs

Agility is a physically demanding sport, and injuries are common. An understanding of the common clinical presentations, frequent injuries, and risk factors for injury is critical when seeing this population of patients in practice. Shoulder injuries and other soft tissue injuries including iliopsoas muscle strains are commonly seen. The Border Collie seems to be at higher risk of developing agility-related injuries. The key to rehabilitation of the agility dog is accurate and expedient diagnosis of the injury, which often involves advanced diagnostics such as musculoskeletal ultrasound, arthroscopy, and/or MRI.

Internet Survey Evaluation of Iliopsoas Injury in Dogs Participating in Agility Competitions

Objective

To describe risk factors associated with demographics, training, and competition for iliopsoas injury in dogs participating in agility competitions, as well as describe owner reported treatment and return to sport following injury.

Procedures

An internet-based survey of agility handlers collected risk factor data for dogs participating in agility. Owners were asked questions about demographics, training, and competition as well as injury treatment and recovery if applicable. Associations between variables of interest and iliopsoas injury were estimated with logistic regression. The final risk factor model was built via modified backward selection, with all variables in the final model showing significant associations at p < 0.05.

Results

Of the 4,197 dogs in the sample, 327 (7.8%) reported iliopsoas injury. The final model identified six risk factors for iliopsoas injury. A higher risk of iliopsoas injury was observed for the Border Collie breed, dogs with handlers who are veterinary assistants, dogs competing on dirt, dogs competing on artificial turf 6+ times a year, and dogs that trained with the 2 × 2 method for weave poles. Dogs that were not acquired with agility in mind were observed to have a decreased risk of injury. Factors like number of competition days and jump height were not significantly associated with risk of iliopsoas injury. Owners sought veterinary care for 88% of dogs with iliopsoas injury, including specialty care for 63%. Treatment most often included rest, home rehabilitation, formal rehabilitation, and/or oral medications. Most dogs (80%) were able to return to sport within 6 months, while 20% were out for longer than 6 months, or retired.

Conclusion and Clinical Relevance

Iliopsoas injury can necessitate a significant amount of time off from training and competition, and even lead to retirement of dogs competing in agility. Some of the risk factors identified in this study can inherently not be modified (breed, intended use, and handler profession), but can be taken into consideration for injury prevention strategies. Competition and training risk factors that can be modified, such as weave training, may help to inform guidelines for best practices in management of the agility athlete.

Risk-Factors for Soft-Tissue Injuries, Lacerations and Fractures During Racing in Greyhounds in New Zealand

Recognition of injuries in racing animals is essential to identify potential risk factors so actions can be taken to reduce or mitigate the cause of the injury to safeguard the animal. Racing greyhounds are subject to musculoskeletal injuries associated with athletic pursuit, in particular soft-tissue injuries, lacerations, and fractures. The objective of this study was therefore to determine risk factors for soft-tissue injuries, lacerations and fractures occurring during racing, using a cohort of greyhounds racing in New Zealand between 10th September 2014 and 31st July 2020. Dog-level, race-level and track-level risk factors for each outcome were assessed using mixed-effects multivariable logistic regression including trainer as a random effect. Throughout the study period there were 218,700 race starts by 4,914 greyhounds, with a total of 4,385 injuries. Of these, 3,067 (69.94%) were classed as soft-tissue injuries, 641 (14.62%) were reported as lacerations, and 458 (10.44%) were fractures. Greyhounds with a low racing frequency (racing more than 7 days apart) had 1.33 [95% confidence interval (CI): 1.06-1.67] times the odds of fracture compared to those racing more frequently. Older greyhounds had a greater odds of fracture compared with younger greyhounds. Racing every 7 days had a lower odds of soft-tissue injury compared with racing more than once a week. Dogs over 39 months had 1.53 (95% CI: 1.35-1.73) times the odds of sustaining a soft-tissue injury compared to the younger dogs. Greyhounds originating from Australia had a higher odds of fracture and laceration compared with New Zealand dogs. Better performing dogs (higher class) had a greater odds of fracture and laceration whilst maiden dogs had a higher odds of soft-tissue injury. Greyhounds starting from the outside box had a higher odds of fracture. There was considerable variation in the odds of soft-tissue injury at different racetracks. In conclusion, although the incidence of soft-tissue injuries was higher than other injury types, the repercussion of such injuries was less than those for fractures. The results from this study will help to inform intervention strategies aimed at reducing the rate of injuries in racing greyhounds, enhancing racing safety and greyhound welfare.

A retrospective descriptive analysis of race-day injuries of greyhounds in New Zealand

OBJECTIVES

To describe the distribution, and determine the incidence, of veterinary reported injuries experienced by greyhounds during racing in New Zealand.

MATERIALS AND METHODS

This retrospective cohort study utilised data obtained on all greyhound race starts and all racing injuries sustained in New Zealand between 10 September 2014 and 19 June 2019. Greyhound injuries were described by the number and percentage of the type, location, and presumed cause of injuries. The overall incidence of injuries per 1000 racing starts was calculated and stratified incidence rates were calculated for race year, racetrack, race number, sex of the greyhound, country of origin of the greyhound, starting box number, race type, race class and race distance. Poisson regression was used to calculate incidence rate ratios for the outcome of injury and race exposure variables.

RESULTS

There were 213,630 race starts and 4100 injuries. The incidence of injury was 19.2 per 1000 starts, while the number of fatalities at the track was 1.3 per 1000 race starts. Most injuries experienced by greyhounds on race-day were minor (soft-tissue). Most injuries affected the limbs of the greyhounds (82.8%, n = 3393/4100). The rate of injuries was higher in Australian dogs compared with New Zealand dogs, the incidence rate of injury increased with advancing age group and the incidence rate varied among racetracks.

CONCLUSION

The injury rates were similar to those previously reported for racing greyhounds in New Zealand. This study highlighted the need for greater uniformity and conciseness around the classification of injuries to permit comparisons across jurisdictions.

Social License and Animal Welfare: Developments from the Past Decade in Australia

"Social license to operate" (SLO) refers to the implicit process by which a community gives an industry approval to conduct its current business activities. It has become an important focus for many natural resource management fields (especially mining), but there is less awareness of its role in animal use industries. This article describes how animal welfare has recently become arguably the most crucial consideration underpinning the SLO for Australian animal use industries. It describes several industries in Australia that have faced animal welfare scrutiny in the past decade (2010-2020) to illustrate how persistent issues can erode SLO, lead to regulatory bans, and decimate previously profitable industries. Industries described include the live export of livestock, greyhound and horse racing, kangaroo harvesting, and dairy and sheep farming. In these cases, there has been intense public discourse but little scholarly progress. This article examines factors that may have contributed to these developments and suggests approaches that may assist these industries in maintaining their SLO. Animal welfare has become a mainstream societal concern in Australia, and effective management of the community's expectations will be essential for the maintenance of SLO for many animal use industries.

TeamMate: A Longitudinal Study of New Zealand Working Farm Dogs. II. Occurrence of Musculoskeletal Abnormalities

Musculoskeletal injury and disease are common in dogs, and a major cause of retirement in working dogs. Many livestock farmers rely on dogs for the effective running of their farms. However, the incidence of musculoskeletal disease has not been explored in working farm dogs. Here we explore the occurrence of musculoskeletal abnormalities in 323 working farm dogs that were enrolled in TeamMate, a longitudinal study of working farm dogs in New Zealand. All dogs were free of musculoskeletal abnormalities on enrolment to the study and were present for at least one follow-up examination. During the follow-up period, 184 dogs (57%, 95% confidence interval (CI) = 52%-62%) developed at least one musculoskeletal abnormality during 4,508 dog-months at risk, corresponding to 4.1 dogs (95% CI = 3.5-4.7) with recorded abnormalities per 100 dog-months at risk. The most common abnormalities were reduced range of motion and swelling of the carpus or stifle, while the hip was the most common site of pain. No major differences in incidence rate (IR) between sexes or types of dogs were observed, though Huntaways had a slightly lower rate of carpal abnormalities than Heading dogs (IR ratio = 0.6, 95% CI = 0.3-1.0). Eighty-one of 119 dogs (68%, 95% CI = 60%-76%) that had a first musculoskeletal abormality developed a second abnormality. The most common type of abnormality that was seen in the same dog more than once was reduced range of motion in the carpus (14 of 119 dogs, 12%, 95% CI = 6%-18%). Although we do not provide data on diagnoses, the high incidence rate of recorded musculoskeletal abnormalities and dogs' high activity mean it is likely that working farm dogs are at a high risk of conditions that could impair their welfare and reduce the lengths of their working careers. Preventing and managing musculoskeletal injury and illness should be a priority for owners and veterinarians caring for working farm dogs.

Patterns of Racing and Career Duration of Racing Greyhounds in New Zealand

Simple Summary

There is limited information on the career length and patterns of racing for greyhounds. Performance outcomes, including number of racing starts, career length and the age at which greyhounds finish racing, provide insight into causes of attrition in the greyhound racing industry. To investigate trends in greyhound racing careers a baseline is required. This paper presents results from a retrospective cohort study exploring career duration and patterns of racing of greyhounds in New Zealand.

Abstract

The welfare and wastage of racing greyhounds is a topic of public concern. Little is published about the racing patterns of these dogs in New Zealand. The aim of this study is to describe the pattern of greyhound racing in New Zealand. Data on all race starts between 1 August 2011 and 25 March 2018 were supplied by Greyhound Racing New Zealand. A cohort was created containing dogs that had a racing career between 1 August 2013 and 31 July 2017. Data were collated within a customized Microsoft Access database from electronic records of all racing starts for every dog within the 2013–2016 racing seasons. For this cohort of racing dogs, there were 97,973 race starts across 22,277 races involving 2393 individual greyhounds. The median number of days between racing starts was 7 days (inter-quartile range (IQR): 4–10 days). The median career length was 424 days (IQR: 206–647 days) and the median number of racing starts throughout a racing career was 35 (IQR: 16–59 starts). Dogs of similar ability finished their career at a similar age.

Greyhound racing ideal trajectory path generation for straight to bend based on jerk rate minimization

This paper presents methods for modelling and designing an ideal path trajectory between straight and bend track path segments for racing greyhounds. To do this, we numerically generate clothoid and algebraic curve segments for racing quadrupeds using a sequential vector transformation method as well as using a helper equation for approaching ideal clothoid segments that would respect greyhound kinematic parameters and boundary conditions of the track. Further, we look into the limitations of using a clothoid curve for racing dog track path design and propose a smooth composite curve for track transition design which roughly maintains G3 curvature continuity for smooth jerk to overcome limitations of a clothoid transition. Finally, we show results from race data modelling and past injury data, which provide a strong indication of clothoid curve segments improving the dynamics and safety of racing greyhounds while reducing injuries.

Internet Survey of Participant Demographics and Risk Factors for Injury in Flyball Dogs

Background: Injury risk in canine sprinting sports, such as greyhound racing and agility, have been previously documented through various surveys. Flyball, another sprinting canine sport with similar athletic requirements to agility, has yet to be assessed for factors associated with injury. The aim of this study was to determine injury prevalence and assess for risk factors for injury in flyball dogs.

Methods: Survey data from 375 flyball participants was collected and analyzed. Data collected included patient-specific variables, equipment use, training/competition practices, and injury occurrence and localization. Univariate analysis was utilized for all variables of interest, followed by backwards nominal logistic regression to identify variables associated with increased risk of injury, with a p < 0.05 defined as significant.

Results: Thirty-nine percent of dogs incurred at least one injury with 172 injuries reported. Injuries to the limbs were common (30.8% affecting forelimbs, 25.6% affecting hindlimbs), with the paw or nail the most frequently reported injured area (19.2%). Only protective wrap use and age were significantly associated with injury in the final nominal regression model (p < 0.01). A biphasic injury rate with more injuries in younger dogs was observed, and injuries peaked by 6 years of age. Use of carpal wraps was positively associated with increased injury risk.

Conclusions: These findings suggest an association between younger dogs and greater risk of injury, as well as identify a need to further investigate the utilization of wraps and potential association between injury risk among flyball participants.

Greyhounds under general veterinary care in the UK during 2016: demography and common disorders

Background

The greyhound is a sighthound known for its speed and agility. Greyhounds were selectively bred as functional racing animals but increasingly are kept as pets in the UK, often after their racing careers are over. The VetCompass™ Programme collates de-identified clinical data from primary-care veterinary practices in the UK for epidemiological research. Using VetCompass™ clinical data, this study aimed to characterise the demography, mortality and common disorders of the general population of pet greyhounds under veterinary care in the UK.

Results

Greyhounds comprised 5419/ 905,544 (0.60%) dogs under veterinary care during 2016 from 626 clinics. Mean adult bodyweight was 29.7 kg (standard deviation [SD] 4.5 kg). Males (32.3 kg, SD 4.1 kg) were heavier than females (27.2 kg, SD 3.3 kg) (P < 0.001). Mean age was 7.6 years (SD 3.4). The most common colours were black (39.2%), black and white (20.8%), brindle (12.0%). Based on 474 deaths, median longevity was 11.4 years (range 0.2–16.5). Females (11.8 years) outlived males (11.2 years) (P = 0.002). The most common grouped causes of death were neoplasia (21.5%, 95% CI: 17.4–26.0), collapse (14.3%, 95% CI: 10.9–18.2) and musculoskeletal disorder (7.8%, 95% CI: 5.3–11.0). Based on a random subset of 2715/5419 (50.1%) greyhounds, 77.5% had > 1 disorder recorded during 2016. The most prevalent specific disorders were periodontal disease (39.0%, 95% CI: 37.2–40.9), overgrown nails (11.1%, 95% CI 10.0–12.4), wound (6.2%, 95% CI: 5.3–7.1), osteoarthritis (4.6%, 95% CI: 3.8–5.4) and claw injury (4.2%, 95% CI: 3.4–5.0).

Conclusions

These findings highlight the greyhound as a relatively common pet dog breed in the UK, accounting for 0.6% of dogs under primary veterinary care. Dental disease, trauma and osteoarthritis were identified as common health issues within the breed. Knowledge of common disorders can help greyhound breeders and regulators to prioritise breeding, rearing and racing management to mitigate some of the most prevalent issues. Greyhound rehoming organizations can also better inform adopters about prophylactic care.

Peak forelimb ground reaction forces experienced by dogs jumping from a simulated car boot

Many dog owners allow their pets to jump out of a car boot; however, to date, there has been no study that has investigated whether this places dogs at risk of injury. The aim of this study was to investigate the relationship between height and peak vertical ground reaction force (vGRF) in static start jumps. Fifteen healthy adult dogs performed three jumps from a platform that represented common vehicle boot sill heights (0.55, 0.65, 0.75 m), landing on a single force platform. Kinetic data (mediolateral (Fx), craniocaudal (Fy) and vertical (Fz)) were normalised for body weight and analysed via a one-way repeated analysis of variance (ANOVA) and pairwise post hoc tests with a Bonferroni correction applied. There was a significant difference in peak forelimb vGRF between both the 0.55 m (27.35±4.14 N/kg) and the 0.65 m (30.84±3.66 N/kg) platform (P=0.001) and between the 0.65 and 0.75 m (34.12±3.63 N/kg) platform (P=0.001). There was no significant difference in mediolateral or craniocaudal forces between the heights examined. These results suggest that allowing dogs to jump from bigger cars with a higher boot sill may result in augmented levels of loading on anatomical structures. Further research is required to investigate the kinematic effects of height on static jump-down and how peak forelimb vGRF relates to anatomical loading and subsequent injury risk.

Central tarsal bone fracture in a cat

Fracture of the central tarsal bone is an uncommon injury in dogs and occurs predominantly in racing Greyhounds. To the authors' knowledge, this type of fracture has not been described previously in cats. This case report describes a five-year-old Domestic Shorthair cat referred to the Centro Veterinario Luni Mare because of lameness, swelling and signs of pain in the right hindlimb caused by trauma. Clinical examination and diagnostic imaging revealed a right central tarsal bone fracture. Open reduction and internal fixation with a 2.0 mm position screw and two 0.8 mm Kirschner wires were carried out. The last follow-up examination three years postoperatively found the cat in good health with normal range of motion and function, and no signs of lameness in the right hindlimb.

Thermographic imaging of the superficial temperature in racing greyhounds before and after the race

A total of 47 racing greyhounds were enrolled in this study on two race days (in July and September, resp.) at a racetrack. Twelve of the dogs participated in the study on both days. Thermographic images were taken before and after each race. From the images, superficial temperature points of selected sites (tendo calcaneus, musculus gastrocnemius, musculus gracilis, and musculus biceps femoris portio caudalis) were taken and used to investigate the differences in superficial temperatures before and after the race. The thermographic images were compared between the right and left legs of a dog, between the raced distances, and between the two race days. The theoretical heat capacity of a racing greyhound was calculated. With regard to all distances raced, the superficial temperatures measured from the musculus gastrocnemius were significantly higher after the race than at baseline. No significant differences were found between the left and right legs of a dog after completing any of the distances. Significant difference was found between the two race days. The heat loss mechanisms of racing greyhounds during the race through forced conduction, radiation, evaporation, and panting can be considered adequate when observing the calculated heat capacity of the dogs.

Dorsal slab fracture of the fourth carpal bone in a racing greyhound

OBJECTIVE

To report the diagnosis and surgical management of a dorsal slab fracture of the fourth carpal bone in a racing greyhound.

STUDY DESIGN

Clinical report.

ANIMAL

Three-year-old, male racing Greyhound.

METHODS

The fracture was not visible on orthogonal radiographs and the diagnosis was made by computed tomography. Open reduction and internal fixation with 2 countersunk 2.0-mm screws inserted in lag fashion was performed via a dorsal approach. Outcome was analyzed objectively by comparing preinjury and postsurgery racing performances.

RESULTS

Internal fixation resulted in fracture healing and the dog returned to racing recording times similar to those before injury.

CONCLUSION

Fractures of the fourth carpal bone may not be visible on standard orthogonal radiographic views and cross-sectional imaging may be required for more accurate identification. Surgical management was successful with the dog returning to preinjury levels of competition.

Observer variation in the evaluation and classification of severe central tarsal bone fractures in racing Greyhounds

OBJECTIVES

To determine observer agreement on radiographic evaluation of central tarsal bone (CTB) fractures and compare this with evaluation of the same fractures using computed tomography (CT).

METHODS

Radiographs and CT scans were obtained of the right tarsi from limbs of Greyhounds euthanatized after sustaining severe CTB fracture during racing. Four observers described and classified each fracture. Inter- and intra-observer agreements were calculated.

RESULTS

Inter-observer agreement was higher for assessment of fractures using CT. Several fractures assessed by radiography were misclassified as a less severe type. Intra-observer agreement for assessment and classification of CTB fractures via radiography versus CT was variable. Overall agreement among all four observers was higher for CT than radiography. Additionally, when identifying fractures of the adjacent tarsal bones, observer agreement was higher for CT than radiography.

CLINICAL SIGNIFICANCE

Computed tomography improved observer ability to correctly evaluate CTB fracture and detect the degree of displacement and extent of any comminution. Identification of fractures of adjacent tarsal bones was also improved when tarsi were assessed using CT. These data suggest that treatment decisions based solely on radiographic assessment of CTB fractures may not produce the expected outcome.

Relationship between muscle forces, joint loading and utilization of elastic strain energy in equine locomotion

Storage and utilization of strain energy in the elastic tissues of the distal forelimb of the horse is thought to contribute to the excellent locomotory efficiency of the animal. However, the structures that facilitate elastic energy storage may also be exposed to dangerously high forces, especially at the fastest galloping speeds. In the present study, experimental gait data were combined with a musculoskeletal model of the distal forelimb of the horse to determine muscle and joint contact loading and muscle–tendon work during the stance phase of walking, trotting and galloping. The flexor tendons spanning the metacarpophalangeal (MCP) joint – specifically, the superficial digital flexor (SDF), interosseus muscle (IM) and deep digital flexor (DDF) – experienced the highest forces. Peak forces normalized to body mass for the SDF were 7.3±2.1, 14.0±2.5 and 16.7±1.1 N kg–1 in walking, trotting and galloping, respectively. The contact forces transmitted by the MCP joint were higher than those acting at any other joint in the distal forelimb, reaching 20.6±2.8, 40.6±5.6 and 45.9±0.9 N kg–1 in walking, trotting and galloping, respectively. The tendons of the distal forelimb (primarily SDF and IM) contributed between 69 and 90% of the total work done by the muscles and tendons, depending on the type of gait. The tendons and joints that facilitate storage of elastic strain energy in the distal forelimb also experienced the highest loads, which may explain the high frequency of injuries observed at these sites.

Determinants of passive hip range of motion in adult Greyhounds

OBJECTIVE

To determine the ranges of normal pelvic limb range of motion in adult Greyhound dogs, and to explore which factors influence hip range of motion in a population bred to meet the specific demands of racing. Design A cross-sectional study design.

METHOD

Thirty-two dogs (17 male and 15 female) 13 to 81 months old were randomly selected from a local pool of 160 Greyhounds. Goniometric measurements of hip, stifle and hock range of motion were recorded in triplicate. Signalment information collected included sex, weight and age of each Greyhound. The outcome factors for the study were range of hip flexion and hip extension. The theorised exposures, age, sex, weight, racing history and hock and stifle range of motion, were modelled against the outcome variables by linear regression analysis.

RESULTS

Male dogs were significantly heavier (P < 0.001) and older (P < 0.002) than female dogs. Mean hip flexion was 71.75 degrees and mean hip extension 128.10 degrees. The determinants of hip flexion were sex (P = 0.008) and range of stifle flexion (P = 0.002). Race training did not influence the range of hip flexion in the sample. Determinants of hip extension included range of stifle extension (P = 0.015), history of race training (P = 0.004) and hock flexion. The mean hip extension of raced Greyhounds was 134.95 degrees compared with 121.25 degrees for unraced Greyhounds (mean difference -13.70, 95% confidence interval -18.12, -9.29; P < 0.001).

CONCLUSIONS

This study has reported isolated pelvic limb joint range of motion in the racing Greyhound. Hip range of motion was affected by stifle range of motion, sex and race training. Dogs that had received race training had greater flexibility, possibly due to training having an active stretching role on muscles, tendons and other structures limiting the hip range of motion.

Rehabilitation and Conditioning of Sporting Dogs

Owners and trainers exercise sporting dogs to increase their fitness and optimize their conditioning and performance. Training is designed to in-crease strength, endurance, and agility and is sport-specific. Sporting dogs are susceptible to specific musculoskeletal injuries. The rehabilitation of sporting dogs after these injuries follows specific principles during the acute, subacute, and reconditioning periods.

Functional trade-offs in the limb bones of dogs selected for running versus fighting

The physical demands of rapid and economical running differ from the demands of fighting in ways that may prevent the simultaneous evolution of optimal performance in these two behaviors. Here, we test an hypothesis of functional trade-off in limb bones by measuring mechanical properties of limb bones in two breeds of domestic dog (Canis lupus familiaris L.) that have undergone intense artificial selection for running (greyhound) and fighting (pit bull) performance. The bones were loaded to fracture in three-point static bending. To correct for the effect of shear, we estimated the shear stress in the cross section and added energy due to shear stress to the tensile energy. The proximal limb bones of the pit bulls differed from those of the greyhounds in having relatively larger second moments of area of mid-diaphyseal cross sections and in having more circular cross-sectional shape. The pit bulls exhibited lower stresses at yield, had lower elastic moduli and failed at much higher levels of work. The stiffness of the tissue of the humerus, radius, femur and tibia was 1.5-2.4-fold greater in the greyhounds than in the pit bulls. These bones from the pit bulls absorbed 1.9-2.6-fold more energy before failure than did those of the greyhounds. These differences between breeds were not observed in the long bones of the feet, metacarpals and metatarsals. Nevertheless, the results of this analysis suggest that selection for high-speed running is associated with the evolution of relatively stiff, brittle limb bones, whereas selection for fighting performance leads to the evolution of limb bones with relatively high resistance to failure.

Site-specific adaptive remodeling of Greyhound metacarpal cortical bone subjected to asymmetrical cyclic loading

OBJECTIVE

To quantify geometric, inertial, and histomorphometric properties at the mid-diaphyseal level of left and right metacarpal bones (MCB) of racing Greyhounds.

SAMPLE POPULATION

MCB from 7 racing Greyhounds euthanatized for reasons unrelated to MCB abnormalities.

PROCEDURES

Mid-diaphyseal transverse sections of left and right MCB were stained with H&E or microradiographed. Images of stained sections were digitized, and cross-sectional area, cortical area, and maximum and minimum area moments of inertia of each bone were determined. Histomorphometric data (osteonal density, osteonal birefringence, and endosteal new lamellar bone thickness) were collected in 4 quadrants (dorsal, palmar, lateral, medial). Values were compared between limbs and among bones and quadrants.

RESULTS

Cross-sectional area, cortical area, and maximum and minimum moments of inertia of left MCB-IV and -V were significantly greater, compared with contralateral bones. Overall osteonal densities in the dorsal quadrants of left MCB were greater, compared with lateral and medial quadrants. Also, percentage of birefringent osteons was significantly greater in the dorsal quadrant of left MCB-III, -IV, and -V, compared with the palmar quadrant. Thickness of new endosteal lamellar bone was not significantly influenced by limb, bone, or quadrant.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased cortical thickness and geometric properties of left MCB-IV and -V of Greyhounds, together with altered turnover and orientation of osteons in the dorsal quadrants of left MCB, are site-specific adaptive responses associated with asymmetric cyclic loading as a result of racing on circular tracks. Site-specific adaptive remodeling may be important in the etiopathogenesis of fatigue fractures in racing Greyhounds.