Profiling the New Zealand Thoroughbred racing industry. 2. Conditions interfering with training and racing

AIM: To describe and enumerate conditions that interrupted training and racing in a population of Thoroughbred racehorses in New Zealand.

METHODS: A longitudinal study design was used to collect data on horses training under the care of 20 licensed racehorse trainers from venues in the mid to lower regions of the North Island between October 1997 and July 2000. Incidence rates were reported for first and second occurrences for different categories of musculoskeletal injury (MSI), and first occurrences of upper and lower respiratory tract disease, using training days as time-at-risk. The proportion of horses that retired or died due to MSI, respiratory tract or miscellaneous conditions was used to estimate risk of exit for each type of event. Duration of training preparation, starts per 100 training days, and proportion of starts that ended in first, second or third place, were calculated for horses at risk for first MSI, and all subsequent MSIs. In training preparations that had at least one start and that ended in MSI, the cumulative percentage of MSIs by day of diagnosis was reported for 0–21 days after the last start in the preparation.

RESULTS: Horses (n=1,571) were followed during 3,333 training preparations and 392,290 training days. Events associated with the end of a training preparation or spell period included MSI (n=834), respiratory event (RE; n=165), miscellaneous event (ME; n=58), and voluntary retirements (n=360). Causes of MSI included lameness (n=400), shin soreness (n=207), tendon and ligament conditions (n=98), injury or laceration (n=56), fractures (n=55), and back disorders (n=18). MSIs involved the limbs in 97% of cases, and the lower limbs up to the carpus or hock in the fore- and hindlimbs, respectively, in 81% of cases. Most (93%) lower limb conditions involved a forelimb while 70% of MSIs that involved structures above the carpus or hock involved a hindlimb. Incidence rates (IRs) are reported for each age group for first and second occurrences of MSI, and first occurrence of upper and lower respiratory tract disease. The risk of MSI was higher in horses that had incurred one previous MSI (RR 1.4, 95% CI=1.2–1.7; p>0.001) than in horses without any previous MSI. The proportion of horses that exited due to death or retirement varied with the type of injury, and the highest proportion was associated with recurrent fractures, and tendon and ligament injuries (46.2 and 44.4%, respectively). The overall IR of horses exiting the study due to retirement or death increased with increasing age, and was higher in females than males for horses aged 2, 3, 4, and ≥5 years. A reduction in the number of starts per 100 training days was observed in horses aged ≥5 years when returning to training after an initial MSI (p=0.004). Male horses of all age groups and females younger than 4 years had shorter median training preparations (p>0.05) when returning to training after an initial MSI compared with preparations at risk for a first occurrence of MSI. Between 27 and 62% of cases of MSI that occurred in training preparations after at least one start were reported on the day of the last start, and the remainder were reported in the days to weeks following the last start of that preparation.

CONCLUSION: Incidence rates, and proportions of affected horses that retired or died as a result of injury or disorder varied with type of injury and age of horse. Horses returning to training after an initial MSI were at higher risk of subsequent MSIs and showed changes in duration of training preparations, but little change in starts per 100 training days or probability of placing in each start. MSIs in racing horses were less likely to be reported on the day of a race than at other times in the training preparation for all ages except 2-year-olds.     

Profiling the New Zealand Thoroughbred racing industry. 2. Conditions interfering with training and racing

AIM: To describe and enumerate conditions that interrupted training and racing in a population of Thoroughbred racehorses in New Zealand. METHODS: A longitudinal study design was used to collect data on horses training under the care of 20 licensed racehorse trainers from venues in the mid to lower regions of the North Island between October 1997 and July 2000. Incidence rates were reported for first and second occurrences for different categories of musculoskeletal injury (MSI), and first occurrences of upper and lower respiratory tract disease, using training days as time-at-risk. The proportion of horses that retired or died due to MSI, respiratory tract or miscellaneous conditions was used to estimate risk of exit for each type of event. Duration of training preparation, starts per 100 training days, and proportion of starts that ended in first, second or third place, were calculated for horses at risk for first MSI, and all subsequent MSIs. In training preparations that had at least one start and that ended in MSI, the cumulative percentage of MSIs by day of diagnosis was reported for 0-21 days after the last start in the preparation. RESULTS: Horses (n=1,571) were followed during 3,333 training preparations and 392,290 training days. Events associated with the end of a training preparation or spell period included MSI (n=834), respiratory event (RE; n=165), miscellaneous event (ME; n=58), and voluntary retirements (n=360). Causes of MSI included lameness (n=400), shin soreness (n=207), tendon and ligament conditions (n=98), injury or laceration (n=56), fractures (n=55), and back disorders (n=18). MSIs involved the limbs in 97% of cases, and the lower limbs up to the carpus or hock in the fore- and hindlimbs, respectively, in 81% of cases. Most (93%) lower limb conditions involved a forelimb while 70% of MSIs that involved structures above the carpus or hock involved a hindlimb. Incidence rates (IRs) are reported for each age group for first and second occurrences of MSI, and first occurrence of upper and lower respiratory tract disease. The risk of MSI was higher in horses that had incurred one previous MSI (RR 1.4, 95% CI=1.2-1.7; p<0.001) than in horses without any previous MSI. The proportion of horses that exited due to death or retirement varied with the type of injury, and the highest proportion was associated with recurrent fractures, and tendon and ligament injuries (46.2 and 44.4%, respectively). The overall IR of horses exiting the study due to retirement or death increased with increasing age, and was higher in females than males for horses aged 2, 3, 4, and > or =5 years. A reduction in the number of starts per 100 training days was observed in horses aged > or =5 years when returning to training after an initial MSI (p=0.004). Male horses of all age groups and females younger than 4 years had shorter median training preparations (p<0.05) when returning to training after an initial MSI compared with preparations at risk for a first occurrence of MSI. Between 27 and 62% of cases of MSI that occurred in training preparations after at least one start were reported on the day of the last start, and the remainder were reported in the days to weeks following the last start of that preparation. CONCLUSION: Incidence rates, and proportions of affected horses that retired or died as a result of injury or disorder varied with type of injury and age of horse. Horses returning to training after an initial MSI were at higher risk of subsequent MSIs and showed changes in duration of training preparations, but little change in starts per 100 training days or probability of placing in each start. MSIs in racing horses were less likely to be reported on the day of a race than at other times in the training preparation for all ages except 2-year-olds.     

Risk factors for musculoskeletal injuries of the lower limbs in Thoroughbred racehorses in New Zealand

AIM: To investigate risk factors for injury to musculoskeletal structures of the lower fore- and hind-limbs of Thoroughbred horses training and racing in New Zealand.

METHODS: A case-control study analysed by logistic regression was used to compare explanatory variables for musculoskeletal injuries (MSI) in racehorses. The first dataset, termed the Training dataset, involved 459 first-occurrence cases of lower-limb MSI in horses in training, and the second, the Starting dataset, comprised a subset of those horses that had started in at least one trial or race in the training preparation that ended with MSI (n=294). All training preparations for horses that did not suffer from MSI for which complete data were available were used in the analyses as controls, and provided 2,181 and 1,639 preparations for the Training and Starting datasets, respectively. Multivariate logistic regression was used to evaluate risk factors, and results were reported as odds ratios (OR) and 95% confidence intervals (CI).

RESULTS: Horses aged ≥5 years were at higher risk of injury than 2-year-olds. Elevated odds of MSI occurred in horses in the Starting dataset that were training in the 1997–1998 year compared with the 1999–2000 year, and in those horses where trials comprised >20% of all starts in a preparation. Training preparations that ended in winter, and horses in their third or later training preparation, had lower odds of MSI compared with those ending in other seasons or the first preparation, respectively. Reduced odds of MSI were observed in preparations in which starts occurred compared with those that had no starts, and in the Starting dataset, preparations that included more than one start had a reduced likelihood of MSI compared with preparations that had only one start. In the Training dataset, preparations longer than 20 weeks were associated with reduced odds of MSI compared with those shorter than 20 weeks.

Cumulative racing distance in the last 30 days of a training preparation was best modelled with linear and quadratic terms. Results indicated that increasing cumulative racing distances were associated with an initial reduction in the odds of MSI that then levelled out and finally appeared to increase again as the explanatory variable continued to increase. The risk of MSI varied significantly between trainers.

CONCLUSION: This study identified intrinsic (age) and extrinsic risk factors for MSI in training and racing Thoroughbreds in New Zealand. The risk of MSI initially decreased, then increased, as cumulative racing distance increased. Significant variation between trainers indicated management and training methods influence the risk of MSI.     

Risk factors for musculoskeletal injuries of the lower limbs in Thoroughbred racehorses in New Zealand

AIM: To investigate risk factors for injury to musculoskeletal structures of the lower fore- and hind-limbs of Thoroughbred horses training and racing in New Zealand. METHODS: A case-control study analysed by logistic regression was used to compare explanatory variables for musculoskeletal injuries (MSI) in racehorses. The first dataset, termed the Training dataset, involved 459 first-occurrence cases of lower-limb MSI in horses in training, and the second, the Starting dataset, comprised a subset of those horses that had started in at least one trial or race in the training preparation that ended with MSI (n=294). All training preparations for horses that did not suffer from MSI for which complete data were available were used in the analyses as controls, and provided 2,181 and 1,639 preparations for the Training and Starting datasets, respectively. Multivariate logistic regression was used to evaluate risk factors, and results were reported as odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Horses aged > or =5 years were at higher risk of injury than 2-year-olds. Elevated odds of MSI occurred in horses in the Starting dataset that were training in the 1997-1998 year compared with the 1999-2000 year, and in those horses where trials comprised >20% of all starts in a preparation. Training preparations that ended in winter, and horses in their third or later training preparation, had lower odds of MSI compared with those ending in other seasons or the first preparation, respectively. Reduced odds of MSI were observed in preparations in which starts occurred compared with those that had no starts, and in the Starting dataset, preparations that included more than one start had a reduced likelihood of MSI compared with preparations that had only one start. In the Training dataset, preparations longer than 20 weeks were associated with reduced odds of MSI compared with those shorter than 20 weeks. Cumulative racing distance in the last 30 days of a training preparation was best modelled with linear and quadratic terms. Results indicated that increasing cumulative racing distances were associated with an initial reduction in the odds of MSI that then levelled out and finally appeared to increase again as the explanatory variable continued to increase. The risk of MSI varied significantly between trainers. CONCLUSION: This study identified intrinsic (age) and extrinsic risk factors for MSI in training and racing Thoroughbreds in New Zealand. The risk of MSI initially decreased, then increased, as cumulative racing distance increased. Significant variation between trainers indicated management and training methods influence the risk of MSI.     

Effect of third carpal slab fracture and repair on racing performance in Thoroughbred horses: 31 cases (1977-1984)

Between 1977 and 1984, 31 Thoroughbred horses (mean age, 2.8 years) were surgically treated for slab fractures of the third carpal bone. All fractures involved the articular surfaces of the intercarpal and the carpometacarpal joints in a frontal plane and had a cuboidal or slab shape. In 20 of the horses, the bone was fractured during racing and in 8 of the horses, the bone was fractured during race training. The right limb was affected more frequently than was the left limb (24 vs 7, P less than 0.05). Twenty-one (67.6%) horses raced at least once after recovery from the surgery. Data were available from 11 claiming horses that had raced at least twice before their injuries and 4 times after recovery. A claiming horse is one that competes where any horse entered is subject to being purchased for the designated amount of the claiming race; therefore, each race tends to automatically attract entrants of similar ability. In this group of 11 horses, claiming value decreased from a mean of $13,900 to a mean of $6,500 (P less than 0.05), and the mean finish position was 5.8 +/- 3.16 before injury and 5.8 +/- 3.30 after recovery. The mean claiming value for horses that had not raced before injury, but had raced after recovery (n = 5) was $8,150.     

Cumulative racing-speed exercise distance cluster as a risk factor for fatal musculoskeletal injury in Thoroughbred racehorses in California

Thoroughbred racehorses which suffered a fatal musculoskeletal injury (FMI) while racing or race training at a California racetrack during 9 months of 1991 were studied to determine the importance of intensive, high-speed exercise schedules prior to injury. Seventy-seven horses which sustained an FMI while racing and 45 horses which sustained an FMI while race training were successfully matched by race or timed workout session with one control horse and included in the analyses. Race and timed workout (racing-speed exercise) histories were obtained for the case and control horses. Two-month cumulative, racing-speed cutoff distances were calculated from the control horse sample by two methods. Median racing-speed exercise frequencies and distances of the control horses were used to estimate age-specific (2, 3, 4 and ≥ 5 years), 2-month cumulative, racing-speed distances (Method 1). For the second method, the last race or timed workout for each control horse occurring just prior to, or on the date of injury for the matched case horse was identified. Cumulative racing-speed distances 2 months prior to these exercise events were determined for each control horse and used to estimate median age-specific (2, 3, 4 and ≥ 5 years), 2-month cumulative racing-speed distances (Method 2). The cumulative cutoff distances estimated from both methods were used to classify each matched pair according to the presence or absence of a 2-month cumulative, racing-speed distance which exceeded the age-appropriate cutoff distance (exercise distance cluster) within 6 months prior to injury. Manlel-Haenszel matched-pair odds ratios and 95% confidence limits were calculated separately for the racing and race-training fatal injuries. The relative risk for racing FMI was significantly greater for those horses which ran 2-month, cumulative racing and timed workout distances in excess of the cutoff values determined with Method 1 (relative risk (RR) = 3.0, 95% confidence interval (CI) = 1.2, 7.6) and Method 2 (RR = 7.2, 95% CI = 2.6, 20.6). The relative risk for race-training FMI was significantly greater for those horses which ran 2-month, cumulative racing and timed workout distances in excess of the cutoff values determined with Method 2 (RR = 3.4, 95% CI =1.0, 13.2).     

Risk factors for and outcomes of noncatastrophic suspensory apparatus injury in Thoroughbred racehorses

OBJECTIVE: To evaluate effects of toe grabs, exercise intensity, and distance traveled as risk factors for subclinical to mild suspensory apparatus injury (SMSAI) in Thoroughbred racehorses and to compare incidence of severe musculoskeletal injury (MSI) in horses with and without SMSAI. DESIGN: Nested case-control study. ANIMALS: 219 Thoroughbred racehorses racing or in race training. PROCEDURE: Racehorses were examined weekly for 90 days to determine incidence of suspensory ligament injury and monitor horseshoe characteristics. Every horse's exercise speeds and distances were recorded daily. Conditional logistic regression was used to compare exposure variables between incident case (n = 25) and selected control (125) horses. Survival analysis was used to compare time to MSI for horses with (n = 41) and without (76) SMSAI. RESULTS: The best-fitting logistic model for the data included age (< 5 vs > or = 5 years old), toe grab height the week of injury (none vs very low, low, regular, or Quarter Horse height), and weekly distance the week preceding injury (miles). Although the 95% confidence intervals for all odds ratios included 1, the odds for SMSAI appeared to increase with the presence of a toe grab, higher weekly distance, and age > or = 5 years. Horses that had SMSAI were significantly more likely to have a severe MSI or severe suspensory apparatus injury than were horses that did not. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that pre-existing SMSAI is associated with development of severe MSI and severe suspensory apparatus injury. Modifying training intensity and toe grab height for horses with SMSAI may decrease the incidence of severe MSI.     

Gastric ulcers in standardbred racehorses: prevalence,lesion description,and risk factors

This study was performed to estimate the prevalence of gastric ulcers in Standardbred racehorses, to describe the lesion score and location, and to identify potential risk factors. Two hundred seventy-five (275) Standardbred horses from 5 training centers and 2 racetracks in Quebec, Canada, were studied. Historical data for the 2 months before examination were recorded for each horse, and the presence of gastric ulcers was determined by gastroscopy. A previously reported scoring system that used grades 0-3 for gastric lesions was used. Overall, 121 horses (44.0%; 95% CI, 38.1-50.1%) had gastric ulcers. The prevalence of gastric ulcers was significantly higher (P < .0001) in actively racing horses (63.3%; 95% CI, 54.7-71.2%) than in horses at rest. Multivariate analysis defined that horses in racing (OR = 9.29; 95% CI, 3.55-24.3) were significantly more likely to have gastric ulcers than horses at rest and that trotters (OR = 2.23; 95% CI, 1.28-3.86) were more likely to have gastric ulcers than pacers. The number of lesion sites (P < .0001) and poor body condition (P < .0001) were significantly associated with lesion scores. Gastric ulcers are highly prevalent in Standardbred racehorses. Furthermore, actively racing horses and trotters are more likely to have gastric ulcers. Also, poor body condition in Standardbred racehorses may be an indication that gastric ulcers are present and that lesion scores are high. The cause-and-effect relationship between poor body condition and the presence of gastric ulcers is unclear.     

An investigation of the relationship between race performance and superficial digital flexor tendonitis in the Thoroughbred racehorse

Reasons for performing study: There is limited information regarding the number of races and the period for evaluation of outcome which is critical for assessment of SDF tendonitis treatments. Objective: To evaluate the re‐injury rate and racing performance of Thoroughbred racehorses that sustain SDF tendonitis in relation to matched controls in terms of number of races post treatment and maximum racing performance ratings before and after injury. Study design: Clinical records and racing histories of 401 racehorses with a first occurrence of SDF tendonitis diagnosed by ultrasonography. Controls were of the same age, sex and were horses training in the same establishment at the time of injury as the case horses and where the trainer reported that the horse had not had a previous SDF tendon injury or treatment. Results: Eighty percent of both case and control horses returned to racing after the date of injury, and the re‐injury proportion within 3 years of treatment was 53%. The difference in Racing Post Rating_(max) (RPR_(max)) and the Racing Post Rating in the race immediately before the treatment date was significantly smaller in case horses (mean = 9.6 lbs; range = 0–75) compared to control horses (mean = 17.0 lbs; range = 0–79). No significant decrease in RPR_(max) was noted post injury. No difference between case and control horses was found for return to racing and racing 3 times, but control horses were significantly more likely to compete 5 races post treatment date than case horses. Conclusion and clinical relevance: Injury was associated with an individual's pre‐injury maximum performance level and return to racing and completion of 3 races are not useful indicator of the outcome of horses with SDF tendonitis. The assessment of the outcome of horses with an SDF injury in a population of racehorses using the number of races post injury requires a minimum of 5 races post injury to be a useful indicator. Further, a re‐injury proportion in a population of horses in training for 3 years post treatment.     

Evaluation of detailed training data to identify risk factors for retirement because of tendon injuries in Thoroughbred racehorses

OBJECTIVE: To identify the risk factors for premature retirement because of tendon injury in a Thoroughbred racehorse population. ANIMALS: 175 Thoroughbred racehorses (cases) at the Hong Kong Jockey Club that were retired from racing because of tendon injury between 1997 and 2004 and for which the last preretirement exercise was at a fast pace were each matched with 3 control horses that were randomly selected from all uninjured horses that had galloped on the same date as that last exercise episode. PROCEDURES: Training data for all horses were examined. Conditional logistic regression analyses were performed to identify risk factors for retirement from racing attributable to tendon injury. Two multivariable conditional logistic regression models were created; each contained 8 explanatory variables. RESULTS: Compared with control horses, case horses were older at the time of import, accumulated more race distance soon after import, were more likely to have had previous official veterinary or ultrasonographic examinations, raced fewer times during their career, and were in training for a longer period and had exercised at a reduced intensity during the 180-day period preceding the last fast-paced work date. CONCLUSIONS AND CLINICAL RELEVANCE: In addition to identification of risk factors for tendon injury among racing Thoroughbreds, results have suggested that resources focused on obtaining accurate training data may be misdirected in the absence of internationally agreed criteria for incident tendon injury among racehorses. Nevertheless, changes in training intensity and findings of previous clinical examinations could be used to identify horses at risk of tendon injury-associated retirement.     

Benefits and risks of barefoot harness racing in Standardbred trotters

There is a lack of research on the benefits and risks of shoeing conditions in harness racing. Thus, our objectives were to: (a) investigate whether velocity times (VT; s/km) are affected by racing unshod (N = 76,932 records on 5,247 horses); (b) determine the potential risks of galloping, being penalized, and disqualification when competing unshod (N = 111,755 records on 6,423 horses); and (c) identify additional environmental factors that affect VT and risks. VT was found to be significantly influenced by shoeing condition (e.g., unshod, shod front, shod hind, or fully shod), but also by sex, age, season, track, track condition, start method, start position, distance, and driver‐horse performance level (p < 2e‐16). The risks of galloping and disqualification were significantly influenced by shoeing condition, sex, age, season, track, start method, start position, or driver‐horse performance level (p ≤ .05). Horses racing unshod had 0.7 s/km lower VT than fully shod horses and showed better performance when racing on neutral tracks during the late summer than horses with other shoeing conditions during the same period. However, racing unshod increased the relative risks of galloping and disqualification by 15%–35% in all seasons. Horses shod only on the hind hooves showed better performance than fully shod horses, without higher risks associated with competing unshod.     

Parameters influencing prevalence and outcome of tendonitis in Thoroughbred and Arabian racehorses

Flexor tendonitis and suspensory desmitis are among most prevalent musculoskeletal injuries observed in racehorses. The aim of this study was to determine which horse and race-related parameters can help to diminish the possibility of injury or--when injury has occurred--to evaluate the potential for the horse to continue a successful career after convalescence. Special attention was given to the comparison of Arabian and Thoroughbred racehorses. 187 horses with ultrasonographically visible lesions were included in the study. Following parameters were analyzed: structure (Superficial Digital Flexor Tendon [SDFT], Deep Digital Flexor Tendon [DDFT], Suspensory Ligament [SL]); percentage of cross sectional area increase; hypoechogenic lesion character; in horses with SDF tendonitis - tendonitis grade according to Genovese. This study showed that Thoroughbreds are more at risk of musculoskeletal problems than Arabian racehorses. In both breeds, the most frequent injuries concern SDFT, then SL. Over 95% of tendonitis concern forelimbs. In Thoroughbreds, the prevalence of tendonitis is higher in bigger horses, in males when compared to females and in fence/steeple racehorses when compared to flat track racehorses. The inside limb is more at risk of SDF tendonitis, when the external limb - of SL desmitis. Tendonitis severity increases with age and is greater in steeplechasers when compared to flat track racehorses. The outcome of tendonitis without hypoechogenic lesion is much better than that with hypoechogenic lesion. Evaluation of hypoechogenic lesion length is an easy and accurate prognosis tool, as the chances of returning to racing drop dramatically with lesions longer than 12 cm.     

添加硫辛酸对焉耆马运动性能、血浆抗氧化能力及代谢指标的影响

试验旨在探讨日粮中添加硫辛酸对焉耆马赛后运动性能、血浆抗氧化能力及代谢指标的影响.选取运动成绩、体重、体尺、年龄相近的焉耆马11匹, 随机分为3组,分别为:对照组(3匹)、试验Ⅰ组(4匹)、试验Ⅱ组(4匹).对照组饲喂基础日粮,试验Ⅰ、Ⅱ组分别在基础日粮中添加12.5、25 g/(d·匹)的硫辛酸.试验开始第20天对各组马匹进行20 km模拟比赛,赛后30 min内测定各组试验马匹的体温、脉搏、呼吸,同时采集各试验组马匹血液.结果表明,无论是赛后0 min还是赛后20 min,试验Ⅰ、Ⅱ组测得的心率均极显著低于对照组(P <0.01);试验Ⅰ组焉耆马血浆中GSH-Px活力比对照组高44.30%(P <0.05);试验Ⅰ、Ⅱ组焉耆马血浆中SOD活力、T-AOC大小分别比对照组高42.33%(P <0.01)、44.72%(P <0.01)和77.41%(P >0.05)、68.62%(P >0.05);试验Ⅰ、Ⅱ组焉耆马血浆中MDA浓度比对照组低41.09%(P <0.05)、23.48%(P >0.05);试验Ⅰ、Ⅱ组焉耆马血浆中NEFA浓度与对照组相比有升高的趋势(P >0.05).在饲料中添加硫辛酸,可提高焉耆马运动性能,有利于焉耆马运动后生理指标的快速恢复,提高运动后焉耆马的抗氧化能力,减缓焉耆马在运动期间的疲劳症状,相比而言,添加12.5 g/(d·匹)硫辛酸组效果较佳.     

Transendoscopic, laser-assisted ventriculocordectomy for treatment of left laryngeal hemiplegia in horses: 22 cases (1999-2005)

OBJECTIVE: To determine long-term effects of transendoscopic, laser-assisted ventriculocordectomy (LAVC) on airway noise and performance in horses with naturally occurring left laryngeal hemiplegia. DESIGN: Retrospective case series. ANIMALS: 22 horses with left laryngeal hemiplegia treated by means of LAVC. PROCEDURES: Medical records were reviewed and initial complaint, intended use of the horse, duration of abnormal airway noise, preoperative performance level, endoscopic findings, surgical procedure, postoperative treatment, and complications were recorded. Follow-up telephone interviews with owners and trainers were conducted to determine time for return to intended use, level of postoperative performance, and percentage reduction in airway noise. RESULTS: All horses were examined because of excessive airway noise; 10 (45%) had concurrent exercise intolerance. Left ventriculocordectomy was performed in all 22 horses; bilateral ventriculocordectomy (right ventriculocordectomy was done 1 year later) was performed in 1 horse (5%). Complications occurred in 3 (14%) horses. Twenty (91%) horses returned to their intended use. Excessive airway noise was eliminated after surgery in 18 (82%) horses; exercise intolerance improved postoperatively in 8 of 10 horses. Three racing Thoroughbreds returned to racing; 1 additional racehorse returned to racing but required a laryngoplasty 1 year later to continue racing. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that LAVC was an effective procedure for elimination of excessive airway noise and improvement of performance in horses with left laryngeal hemiplegia.     

Short‐ and long‐term results following standing fracture repair in 34 horses

Reasons for performing study: Standing fracture repair in the horse is a recently described surgical procedure and currently there are few follow‐up data. This case series contains 2 novel aspects in the standing horse: repair of incomplete sagittal fractures of the proximal phalanx and medial condylar repair from a lateral aspect. Objectives: To describe outcome in a case series of horses that had lower limb fractures repaired under standing sedation at Rossdales Equine Hospital. Method: Case records for all horses that had a fracture surgically repaired, by one surgeon at Rossdales Equine Hospital, under standing sedation and local anaesthesia up until June 2011, were retrieved. Hospital records, owner/trainer telephone questionnaire and the Racing Post website were used to evaluate follow‐up. Results: Thirty‐four horses satisfied the inclusion criteria. Fracture sites included the proximal phalanx (incomplete sagittal fracture, n = 14); the third metacarpal bone (lateral condyle, n = 12, and medial condyle, n = 7); and the third metatarsal bone (lateral condyle, n = 1). One horse required euthanasia due to caecal rupture 10 days post operatively. Twenty horses (66.7% of those with available follow‐up) have returned to racing. Where available, mean time from operation to return to racing was 226 days (range 143–433 days). Conclusions: Standing fracture repair produced similar results to fracture repair under general anaesthesia in terms of both the number of horses that returned to racing and the time between surgery and race. Potential relevance: Repair of lower limb fracture in the horse under standing sedation is a procedure that has the potential for tangible benefits, including avoidance of the inherent risks of general anaesthesia. The preliminary findings in this series of horses are encouraging and informative when discussing options available prior to fracture repair.     

Evaluation of horseshoe characteristics and high-speed exercise history as possible risk factors for catastrophic musculoskeletal injury in thoroughbred racehorses

OBJECTIVE: To evaluate horseshoe characteristics and high-speed exercise history as risk factors for catastrophic musculoskeletal injury in Thoroughbred racehorses. ANIMALS: 377 horses (37,529 race starts). PROCEDURES: Shoe characteristics included material, toe grab height, heel traction device, pads, and rim shoes. Racing variables were obtained from a computerized database. Forty-three horses that had a musculoskeletal injury and then failed to race or train for 6 months (cases) and 334 noninjured horses from the same race in which a horse was injured (controls) were compared regarding risk factors. RESULTS: Overall, 98% of race starts were associated with aluminum shoes, 85% with toe grabs, 32% with pads, and 12% with rims on forelimb horseshoes. Among 43 horses with musculoskeletal injury, sex (geldings), an extended interval since last race, and reduced exercise during the 30 or 60 days preceding injury were risk factors for catastrophic injury. Odds of injury in racehorses with toe grabs on front shoes were 1.5 times the odds of injury in horses without toe grabs, but this association was not significant (95% confidence interval, 0.5 to 4.1). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that horses that return to racing after an extended period of reduced exercise are at high risk of catastrophic musculoskeletal injury. Results regarding the use of toe grabs as a possible risk factor for catastrophic injury were inconclusive because the probability of declaring (in error) that use of toe grabs was associated with an increased risk of musculoskeletal injury (eg, odds ratio > 1.0) was 38%.     

Superior check ligament desmotomy for treatment of superficial digital flexor tendonitis in Thoroughbred and Standardbred horses

Summary Bilateral superior check ligament desmotomy was performed on 31 Thoroughbred and 17 Standardbred horses as the sole method of treatment for superficial digital flexor tendonitis. Horses resumed racing between 6 and 19 months after surgery. Horses that were able to compete in 5 or more races without injury to the tendon again were considered to have had a successful return to racing. Twenty-five Thoroughbreds were suitable for later study and 13 of these (52%) raced on 5 or more occasions. Fifteen Standardbreds were suitable for later study and 10 of these (66%) raced on 5 or more occasions. Within the racing industry it is generally thought that about 20 to 30% of horses with superficial digital flexor tendonitis can return to racing after a prolonged rest. The results of this study suggest that bilateral superior check ligament desmotomy may improve the prognosis for a horse returning to racing after injury to the superficial digital flexor tendon.     

Use of a hydro-pool system to recover horses after general anesthesia: 60 cases

OBJECTIVE: To report complications observed using a hydro-pool recovery system after general anesthesia in horses. STUDY DESIGN: Retrospective study. ANIMALS: Sixty horses. METHODS: Retrospective review of the medical records and quality of recovery from anesthesia of 60 horses that had surgical or diagnostic procedures under general anesthesia. RESULTS: Mean total anesthesia time was 182 minutes (range, 25 to 390 minutes). Mean time in the hydro-pool was 108 minutes (range, 20 to 270 minutes). One horse that had bilateral rear limb extensor weakness while recovering in a padded recovery stall was moved to the hydro-pool and maintained for 12 hours. Ten horses developed some pulmonary edema; in 3 horses, the signs of pulmonary edema were severe; and 1 horse died from related complications. One horse developed septic arthritis of an operated stifle joint, and 2 horses developed incisional infections. Two horses incurred multiple skin abrasions on the distal aspect of their limbs during violent attempts to leave the pool. CONCLUSIONS: A hydro-pool system was useful for recovering horses from general anesthesia when difficult recoveries were anticipated because of the horse's injury, size, demeanor, duration of anesthesia, or risk of further injury. Recovery using the hydro-pool was more time and labor intensive than a standard stall recovery. Pulmonary edema that required treatment was a serious complication that occurred in 17% of the horses. Careful closure of the skin with cyanoacrylate glue and pressure from bandages were used to prevent postoperative incisional infections. CLINICAL RELEVANCE: A hydro-pool system is a useful method for recovering horses from general anesthesia when difficult recoveries are anticipated.