Search Results

You are looking at 51 - 60 of 61 items for

  • Author or Editor: Susan M. Stover x
  • Refine by Access: Content accessible to me x
Clear All Modify Search

Abstract

Objective—To compare hoof acceleration and ground reaction force (GRF) data among dirt, synthetic, and turf surfaces in Thoroughbred racehorses.

Animals—3 healthy Thoroughbred racehorses.

Procedures—Forelimb hoof accelerations and GRFs were measured with an accelerometer and a dynamometric horseshoe during trot and canter on dirt, synthetic, and turf track surfaces at a racecourse. Maxima, minima, temporal components, and a measure of vibration were extracted from the data. Acceleration and GRF variables were compared statistically among surfaces.

Results—The synthetic surface often had the lowest peak accelerations, mean vibration, and peak GRFs. Peak acceleration during hoof landing was significantly smaller for the synthetic surface (mean ± SE, 28.5g ± 2.9g) than for the turf surface (42.9g ± 3.8g). Hoof vibrations during hoof landing for the synthetic surface were < 70% of those for the dirt and turf surfaces. Peak GRF for the synthetic surface (11.5 ± 0.4 N/kg) was 83% and 71% of those for the dirt (13.8 ± 0.3 N/kg) and turf surfaces (16.1 ± 0.7 N/kg), respectively.

Conclusions and Clinical Relevance—The relatively low hoof accelerations, vibrations, and peak GRFs associated with the synthetic surface evaluated in the present study indicated that synthetic surfaces have potential for injury reduction in Thoroughbred racehorses. However, because of the unique material properties and different nature of individual dirt, synthetic, and turf racetrack surfaces, extending the results of this study to encompass all track surfaces should be done with caution.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine major causes of death and the anatomic location of musculoskeletal injuries in Quarter Horse racehorses in California.

Design—Retrospective case series.

Animals—314 Quarter Horse racehorses with musculoskeletal injuries that were necropsied through the California Horse Racing Board Postmortem Program from 1990 to 2007.

Procedures—Postmortem pathology reports were retrospectively reviewed. Musculoskeletal injuries were categorized by anatomic region and described. The number of Quarter Horse starts and starters for the same period of time were obtained from a commercial database for determination of fatal injury incidence.

Results—Musculoskeletal injuries accounted for 314 of the 443 (71 %) Quarter Horse racehorses that died during the 18-year study period. Fatal musculoskeletal injuries occurred at a rate of 2.0 deaths/1,000 race starts and 18.6 deaths/1,000 horses that started a race. Musculoskeletal injuries occurred predominantly during racing (84%) and in the forelimbs (81%). The most common fatal musculoskeletal injuries were metacarpophalangeal and metatarsophalangeal joint (fetlock) support injuries (40%) and carpal (24%), vertebral (10%), and scapular (8%) fractures. Proximal interphalangeal (pastern) joint luxations resulted in death of 3% of horses. Fracture configurations of some bones were consistent with those of Thoroughbred racehorses. Evidence of preexisting stress remodeling of bone was reported for some fractures.

Conclusions and Clinical Relevance—Knowledge of common locations and types of fatal musculoskeletal injuries in racing Quarter Horses may enhance practitioners' ability to detect mild injuries early, rest horses, and help prevent catastrophic injuries.

Full access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

The objective of this study is to compare drilling variables and torsional mechanical properties of rabbit femora after bicortical drilling with a 1.5-mm standard surgical drill bit, acrylic drill bit, and K-wire.

SAMPLES

24 pairs of rabbit femora.

METHODS

After drilling under controlled axial displacement rate, each bone was biaxially loaded in compression followed by rapid external torsion to failure. Maximum axial thrust force, maximum drill torque, integral of force and displacement, change in temperature, maximum power spectral density of the torque signal, torque vibration, and torque and angle at the yield and failure points were collected. Pre- and postyield stiffness, yield and failure energies, and postyield energy were calculated.

RESULTS

The work required to drill through the cis- and transcortices (integral of force and displacement) was greater for the K-wire, followed by the acrylic and then standard drill bits, respectively. The K-wire demonstrated higher maximum torque than the drill bits at the ciscortex, and the force of drilling was significantly greater. The vibration data was greater with the acrylic and standard drill bits than the K-wire. There was no difference in torsional strength between drilling types.

CLINICAL RELEVANCE

Mechanical differences exist between different drill bits and K-wire and demonstrate that the K-wire is overall more damaging than the surgical drill bit.

Open access
in American Journal of Veterinary Research

Objective

To determine whether a two-month or longer period without official high-speed workouts (lay-up) is associated with humeral or pelvic fracture in Thoroughbred racehorses.

Design

Retrospective study.

Animals

Thoroughbred racehorses in California that were euthanatized because of a complete humeral or pelvic fracture.

Procedure

Age, sex, activity, number of lay-ups, number of days from a race or official timed workout to fracture, number of days from end of last lay-up to fracture, mean duration of lay-ups, and total number of days in race training were compared between horses with humeral fractures and horses with pelvic fractures. A case-crossover study was used to estimate relative risk for fracture of the humerus or pelvis occurring within hazard periods of 10 and 21 days following lay-up, compared with periods following more regular participation in official racing or timed workout events.

Results

Horses with pelvic fractures were more often female, older, and had 0 or ≥ 2 lay-ups. Horses with humeral fractures were typically 3-year-old males that had 1 lay-up. Horses with pelvic fractures had more total days in race training, fewer days from last exercise event to fracture, and a greater number of days from end of last lay-up to fracture than horses with humeral fractures. Return from lay-up was strongly associated with risk for humeral fracture during hazard periods of 10 and 21 days (relative risk = 71 and 45, respectively).

Clinical Implications

Risk of humeral fracture may be reduced if horses are cautiously reintroduced into race training after lay-up. (J Am Vet Med Assoc 1998;212: 1582–1587)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate selected shoe characteristics as risk factors for fatal musculoskeletal injury (FMI) and specifically for suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) of Thoroughbred racehorses in California.

Design

Case-control study.

Animals

Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994.

Procedure

Shoe characteristics were compared between case horses affected by FMI (155), SAF (79), and CDY (41) and control horses that died for reasons unrelated to the appendicular musculoskeletal system (non-FMI; 46). Multivariable logistic regression was used to estimate odds ratios for FMI, SAF, and CDY.

Results

Toe grabs were identified as possible risk factors for FMI, SAF, and CDY. The odds of FMI, SAF, and CDY were 1.8, 6.5, and 7.0, respectively, times greater for horses shod with low toe grabs than for horses shod without toe grabs on front shoes. Horses shod with regular toe grabs on front shoes had odds 3.5, 15.6, and 17.1 times greater (P < 0.05) for FMI, SAF, and CDY, respectively, compared with horses shod without toe grabs. The odds of horses shod with rim shoes were a third (P < 0.05) of those shod without rim shoes for either FMI or SAF. The apparent association between toe grab type and CDY may, in part, be attributable to concurrent SAF and CDY injuries in many horses.

Clinical Relevance

Avoiding the use of toe grabs should decrease the incidence of FMI, especially SAF, in Thoroughbred racehorses. The use of rim shoes that are more consistent with natural hoof shape may decrease injury risk. (Am J Vet Res 1996;57:1147-1152)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To develop a standard technique for evaluation of racehorse shoes, to assess homotypic variation (interlimb variation) in shoe characteristics, and to determine whether shoe characteristics varied with age and sex.

Design

Cross-sectional study.

Animals

Thoroughbred racehorses (n = 201) that died or were euthanatized at California racetracks between August 1992 and July 1994.

Procedure

Shoe characteristics were measured on horses examined after death. Percentage of agreement was used to compare shoe characteristics between limbs (homotypic variation). Using χ2analysis, shoe characteristics were compared between horses grouped by age and sex.

Results

Toe grabs were present on 90.5% of horses, and rim shoes were present on 15.9% of horses. Heel traction devices were less frequent on front (2.5%) than rear (6%) hooves. Pads were present on 24.9% of horses, with bonded rim pads most common. Special types of shoes were present on 5% of horses. Percentage of agreement between left and right front hooves and between left and right rear hooves was high (20/25 variables; % agreement ≥ 99). In contrast, percentage of agreement between left front and left rear hooves and between right front and right rear hooves was low (2/25 variables; % agreement ≥ 99). Presence of a pad was significantly (P < 0.05) associated with age, and several shoe variables (size, presence of a special shoe, overall wear matched) were significantly (P < 0.05) associated with sex.

Clinical Relevance

Except for variables related to special shoes, wear, and weight, 1 shoe for the respective fore- or hind limbs could be used as an indicator for the contralateral shoe worn by Thoroughbred racehorses without substantial loss of information. However, 1 shoe could not be used as an indicator for shoe characteristics of all 4 limbs. Some shoe characteristics are associated with age and sex, and these variables should be considered possible confounders in studies of shoe characteristics. (Am J Vet Res 1996;57:1141-1146)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To describe clinical and scintigraphic abnormalities in horses with a bone fragility disorder.

Design—Retrospective case series.

Animals—16 horses with scintigraphic evidence of multiple sites of increased radiopharmaceutical uptake (IRU).

Procedures—Medical records were reviewed for information on signalment; history; clinical, clinicopathologic, and diagnostic imaging findings; and treatment. Follow-up information was obtained through telephone interviews with owners.

Results—Horses ranged from 4 to 22 years old; there were 8 castrated males and 8 females. Foci of IRU most commonly involved the scapulae, ribs, sternebrae, sacral tubers, ilia, and cervical vertebrae. Most horses were examined because of chronic intermittent (n = 10) or acute (6) lameness involving a single (10) or multiple (6) limbs that could not be localized by means of regional anesthesia. Cervical stiffness (n = 3), scapular bowing (3), swayback (3), and ataxia (1) were also seen in more advanced cases. Signs of respiratory tract disease and exercise intolerance were evident in 4 horses. Ultrasonographic or radiographic evidence of bone remodeling or degeneration was seen in 19 of 33 affected bones. Histologic examination of bone biopsy specimens revealed reactive bone. Improvement was initially seen with conservative treatment in some horses, but the condition worsened in all horses, and 11 horses were euthanized within 7 years.

Conclusions and Clinical Relevance—Results suggested that horses may develop a bone fragility disorder characterized clinically by an unlocalizable lameness and scintigraphically by multiple sites of IRU involving the axial skeleton and proximal portion of the appendicular skeleton.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To evaluate hoof size, shape, and balance as risk factors for catastrophic musculoskeletal injuries (CMI), including suspensory apparatus failure (SAF) and cannon bone condylar fracture (CDY) in Thoroughbred racehorses.

Animals

95 Thoroughbred racehorses that died between 1994 and 1996.

Procedure

38 quantitative measures of hoof size, shape, and balance were obtained from orthogonal digital images of the hoof and were compared between case horses with forelimb CMI (70), SAF (43), and CDY (10) injuries and control horses whose death was unrelated to the musculoskeletal system (non-CMI, 25). Comparison of group means between cases and controls was done using ANOVA, and multivariable logistic regression was used to estimate odds ratios.

Results

Odds of CMI were 0.62 times lower for a 5- mm increase in ground surface width difference and 0.49 times lower for a 100-mm2 increase in sole area difference. Odds of SAF were 6.75 times greater with a 10° increase in toe-heel angle difference and 0.58 times lower with a 100-mm2 increase in sole area difference. Odds of CDY were 0.26 times lower with a 3° increase in toe angle, 0.15 times lower with a 5- mm increase in lateral ground surface width, and 0.35 times lower with a 100-mm2 increase in sole area difference.

Clinical Relevance

Decreasing the difference between toe and heel angles should decrease risk of SAF for Thoroughbred racehorses and should be considered in addition to increasing toe angle alone to help prevent catastrophic injury. Trimming the hoof to perfect mediolateral symmetry may not be a sound approach to avoiding injury. (Am J Vet Res 1998;59: 1545-1552)

Free access
in American Journal of Veterinary Research

Objective

To investigate relationships of several racehorse characteristics and race conditions with risk of a catastrophic musculoskeletal injury (CMI) resulting in euthanasia in Thoroughbreds during racing in California in 1992.

Design

Retrospective longitudinal study.

Animals

Thoroughbreds that incurred CMI during racing and all California race entrants in 1992.

Procedure

Necropsy records were reviewed, and race start information was obtained. Incidence risk of CMI/1,000 race entrants was estimated. Relationships between CMI during racing and race-meet, entrant age and sex, race type and length, and racing surface type and condition were evaluated by use of logistic regression.

Results

Incidence risk of CMI was 1.7/1,000 entrants. A higher risk of CMI was found at 2 fair race-meets, with incidence risks of 4.9 and 5.5/1,000 entrants. Risk of injury in male horses was 1.7 times greater than that in female horses, and influence of age on risk depended on race type. Risk of injury for horses 2 to 5 years old was two times greater for claiming horses than for maiden horses. Race length or racing surface type (dirt vs turf) or condition (fast, muddy, yielding) were not significantly associated with risk of CMI.

Clinical Implications

Incidence of CMI was similar among 12 of 14 major and fair race-meets and among various race lengths and racing surface types and conditions, whereas incidence of CMI was influenced by entrant age and sex as well as race type. Investigators should consider controlling for age and sex, race-meet, and race type whenever possible in studies of risk of CMI. (J Am Vet Med Assoc 1998; 212:544-549)

Free access
in Journal of the American Veterinary Medical Association

Objective

To characterize and contrast data from Thoroughbreds that incurred a fatal musculoskeletal injury ( fmi; injury resulting in death or euthanasia) during racing or training and data from all California race entrants during a 9-month period in 1991.

Design

Case-control study.

Animals

Thoroughbreds that incurred a fmi during racing or training at a California race-meet and all California race entrants from January through June and October through December 1991.

Procedure

Age and sex were compared with χ2 and Fisher's exact tests among horses fatally injured while racing and training. A log-linear model was fit to assess the relationship between race-meet and age and sex of California race entrants. Incidence risk of racing fmi was estimated per 1,000 race entrants, and the relationship between the occurrence of fmi during racing with race-meet, age, and sex was evaluated by logistic regression.

Results

Injury type and sex-specific age distributions differed among the horses fatally injured during racing and training. Age and sex distributions of the race entrants were not independent and varied among race-meets. Overall incidence risk of racing fmi was estimated at 1.7/1,000 race entrants. Risk of racing fmi in male horses was about twofold that in female horses, and in 4-year-olds was twofold that in 3-year-olds.

Clinical Implications

Age- and sex-related differences in risk of incurring a fmi during racing should be considered when comparing fatal injury rates among race-meets.

Free access
in Journal of the American Veterinary Medical Association