Abnormal radiographic findings in 865 French Standardbred trotters and their relationship to racing performance

A cross-sectional study on performance evaluation in Italian standardbred horses' real-time PCR-positive for Theileria equi

BACKGROUND

Inflammatory myopathy and perivasculitis have been recently described in horses with chronic equine piroplasmosis (EP). These alterations may be linked to poor performances. The aims of this study were to evaluate the prevalence for EP in clinically healthy Italian Standardbred (IS) racehorses and to compare laboratory parameters and performance metrics between positive and negative horses. Real-time PCR was applied for the detection of T. equi and B. caballi positivity. Haematology parameters, blood chemistry results, subjective muscle mass scores, and performance metrics were compared between PCR-positive and -negative horses.

RESULTS

This cross-sectional study included 120 well-trained IS racehorses and was performed over a two-years period. The prevalence of T. equi was 36.3%, whereas all samples were negative for B. caballi. Red blood cells count, haemoglobin concentration, aspartate aminotransferase, alkaline phosphatase, and gamma-glutamyl transferase activities were significantly higher in PCR-positive horses, whereas blood urea nitrogen, globulin concentration and globulin-to-albumin ratio were significantly lower in PCR-positive horses compared to PCR-negative ones. Nonetheless, all values fell within the physiological range. The best racing time, which was selected as the most representative of the performance metrics at the principal component analysis, was not affected by PCR positivity, the muscle mass score or the training yard. The best racing time was significantly better in horses with a mild or no signs of muscular atrophy, within the PCR-positive group. The muscle mass score was associated with the training yard in PCR-negative horses.

CONCLUSIONS

Prevalence of T. equi was high in IS racehorses in southern Italy. The absence of obvious changes in haematological and biochemical parameters, as well as performance metrics in positive horses, highlights the need for specific diagnostic tests to identify chronically infected horses.

Radiographic prevalence of juvenile osteochondral conditions of the proximal interphalangeal joint of Australian Thoroughbred racehorse yearlings and associations with sales results and race performance

Objectives

Ascertain the radiographic prevalence and variation in characteristics of juvenile osteochondral conditions (JOC) in the proximal interphalangeal joint (PIPJ) of Australian Thoroughbred racehorse yearlings. Establish whether there are any significant associations with public auction sale results and racing performance.

Methods

Retrospective evaluation of 1,098 yearling repository radiograph sets. Comparison of sales results and whole career racing performance of the case group with two control groups: maternal siblings (N = 397) and yearlings without PIP JOC (N = 391).

Results

6.3% of yearlings had at least one PIPJ JOC lesion with 4.8% having subchondral lucencies of the proximal phalanx (P1SC), 0.6% with subchondral lucencies of the middle phalanx (P2SC) and 0.8% with osteochondral fragmentation (OCF). P1SC were more prevalent in forelimbs and P2SC and OCF were more commonly located in the hindlimbs. 51% of PIPJ JOC were not identified on a lateromedial projection (LM). A significantly lower proportion of horses with OCF were successfully sold at public auction (p ≤ 0.05) but there was no significant difference in sales price between the case group and controls. A lower proportion of horses with PIPJ JOC made it to the racetrack to race, although this was not statistically significant. There was no significant difference in racing performance between the case group and controls, although there was a trend toward case horses earning lower career prize money and lower prize money per race (p ≤ 0.1). Lesions located in a dorsal or palmar/plantar location on the LM projection earned a lower average prize money per race (p ≤ 0.05) than those in a central location, and showed a trend toward earning lower total prize money (p ≤ 0.1) and number of places (p ≤ 0.1). There was no significant difference in performance for horses with lesions at the medial, axial or lateral aspects of the articular surface.

Clinical importance

Overall, the findings of this study indicate that the presence of PIPJ JOC in radiographs of Thoroughbred yearlings should be attributed a low to moderate risk to future racing performance, however certain lesion characteristics may be associated with decreased performance.

Influence of osteochondrosis on the longevity and racing performance of standardbred trotters and pacers

OBJECTIVE

To determine the influence of clinical osteochondrosis (OC) on the short-term (2, 3, and 4-year-old) and long-term racing performance and longevity of standardbred racehorses.

STUDY DESIGN

Retrospective case-control study.

SAMPLE POPULATION

Standardbred racehorses from a single breeding farm born between 2009 and 2017 that survived to racing age (n = 2711). Three hundred eighty-two (14%) horses were OC-affected (829 lesions confirmed arthroscopically during surgical treatment), and 2329 (86%) horses were nonaffected.

METHODS

Racing performance data were obtained from an online database and evaluated with multiple linear regression models.

RESULTS

Trotters were more likely than pacers to be affected by OC (odds ratio [OR] = 1.4, 95% CI = 1.1-1.9, P = .006). Compared with nonaffected horses, long-term OC-affected horses had 8.8 fewer starts (95% CI = -14.4 to -3.2, P = .002), 1.0 fewer wins (95% CI = -1.9 to -0.1, P = .030), and 3.8 fewer total number of first through third place finishes (95% CI = -6.2 to -1.4, P < .0001). Nonaffected horses had longer careers compared with OC-affected horses, racing 0.32 years longer (95% CI = -0.52 to -0.12, P = .002). Osteochondrosis had no impact on short-term racing performance. Horses with lesions at the distal intermediate ridge of the tibia or lateral trochlear ridge of the talus had decreased performance compared with horses without these lesions.

CONCLUSION

Pacers were less likely than trotters to be affected by OC. Affected horses had fewer starts and shorter careers, despite early surgical intervention.

CLINICAL SIGNIFICANCE

Osteochondrosis decreases long-term racing performance in racing standardbreds.

Prevalence of Radiographic Signs of Osteoarthritis in Lusitano Purebred Horses

Radiographic prevalence and correlation of radiographic findings has not been performed in Lusitano Purebred horses. The aim of this study was to (1) evaluate the prevalence of primary osteoarthritis radiographic findings in Lusitano Purebred horses; (2) to assess correlations between radiographic findings in different joints of the same limb and different limbs; and (3) elucidate the effect of age in the radiographic findings. A radiographic protocol of the stifle, tarsi, fetlocks and distal limbs was done in 98 Lusitanos and the classification of the radiographs was performed using a 0-4 scale developed and applied blindly by three veterinarians. The distal interphalangeal, proximal interphalangeal, metacarpophalangeal, metatarsophalangeal, tarsometatarsal, distal intertarsal, proximal intertarsal/, tibiotarsal and femorotibial-patellar joints were evaluated. Most joints presented no abnormal findings or minor abnormal radiographic findings (82.86% grade ≤1). The most affected joint was tarsometatarsal and more severe lesions were found in tarsometatarsal and distal intertarsal. Femorotibial-patellar radiographic changes were rare (2.13%). A strong/moderate correlation was found between contralateral joints with exception hindlimb fetlocks. A moderate correlation was found between fore and hindlimbs for distal limb joints. When analyzing ipsilateral as well as diagonal distal limbs, a strong/moderate correlation was also found. The total score progressed in 0.2 score points per each year of age, revealing that age can be a statistically significant predictor for radiographic changes. Overall, Lusitano horses presented a low prevalence of severe radiographic sings of primary osteoarthritis. Findings in contralateral joints tend to be correlated.

Is Sclerostin Glycoprotein a Suitable Biomarker for Equine Osteochondrosis?

Osteochondrosis (OC) disease appears to be multifactorial in origin, including skeletal growth rates, nutrition, endocrinological factors, exercise, biomechanics, and other environmental factors. Endocrinological and metabolic factors seem to have an important role in the pathogeny of OC like the Wnt signaling pathway. One of the regulators in the Wnt signaling pathway is the sclerostin glycoprotein. The aim of this study was to investigate the sclerostin blood concentration according to the evolution of the disease, the environment, and the age but also its use as a possible biomarker for OC disease. Relation between age and sclerostin concentrations was calculated by a linear regression. A relation was found between age and sclerostin concentrations, but also a significant relation between age and the sclerostin concentrations was observed for two subgroups (OC affected and healthy). Evolution of the disease related to the sclerostin concentration was assessed with two logistic regressions (risk of developing OC and recovery of existing lesions), but not any significance was found. In conclusion, these results show that, despite the possible link of sclerostin with the OC pathogenesis through the Wnt pathway, circulating levels of this glycoprotein shall not be used as a biomarker for the disease. Besides, more studies are needed to fully understand the functions of sclerostin in the equine specie since it may play an important role in bone homeostasis.

Outcome after arthroscopic treatment of lateral femoral trochlear ridge osteochondrosis in sport horses

Objectives: To determine the short- and long-term outcome for sport horses after arthroscopic treatment of osteochondrosis of the lateral trochlear ridge of the femur.

Methods: A retrospective study was performed using the medical records of horses intended for use as English sport horses. Outcome was obtained through telephone questionnaire.

Results: Thirty-seven horses, mainly Warmbloods, underwent arthroscopic surgery for treatment of lateral femoral trochlear ridge osteochondrosis. Short-term outcome revealed that 27 of 37 horses had no complications. Seven horses had postoperative lameness and effusion which eventually resolved in four horses. Long-term outcome was available for 29 horses, of which 19 were performing to full expectations. Five horses were athletic but at a lower level than expected, and five horses were unable to be used. The depth of the lesion was significantly associated with short-term complications of effusion and lameness. The depth and length of the lesion were not associated with the long-term outcome, but involvement of structures other than the lateral trochlear ridge (patella, medial trochlear ridge) was associated with a worse prognosis.

Clinical significance: The prognosis for sport horses following stifle arthroscopy for lateral trochlear ridge is similar to that reported in other studies and lesions at other sites within the stifle joint.

Short- and long-term racing performance of Standardbred pacers and trotters after early surgical intervention for tarsal osteochondrosis

REASONS FOR PERFORMING STUDY

Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature.

OBJECTIVE

To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC.

STUDY DESIGN

Retrospective clinical study.

METHODS

The study population consisted of related, age-matched Standardbred racehorses (n = 278; 151 pacers, 127 trotters) with (n = 133) or without (n = 145) one or more tarsal OC lesions. All OC-affected horses were treated surgically prior to being sold as yearlings. Data obtained from publicly available race records for each horse included starts, wins, finishes in the top 3 (win, place or show), earnings and fastest time. Comparisons between OC-affected and unaffected horses were made for the entire population and within gaits. A smaller related population (n = 94) had these performance measures evaluated for their 2-5-year-old racing seasons.

RESULTS

Osteochondrosis status was associated with few performance measures. Trotters were at higher risk for lesions of the medial malleolus but lower risk for lesions of the distal intermediate ridge of the tibia than were pacers. Horses with bilateral OC lesions and lateral trochlear ridge (LTR) lesions started fewer races at 2 years of age than those with unilateral lesions or without LTR lesions.

CONCLUSIONS

Osteochondrosis seemed to have minimal effect on racing performance in this cohort, although horses with bilateral and LTR lesions started fewer races at 2 years. There was evidence for different distribution of OC lesions among pacers and trotters, which should be explored further. Standardbreds undergoing early removal of tarsal OC lesions can be expected to perform equivalently to their unaffected counterparts.

Racing performance in Standardbred trotting horses with proximal palmar/plantar first phalangeal fragments relative to the timing of surgery

REASONS FOR PERFORMING STUDY

Proximal palmar/plantar osteochondral fragmentation of the first phalanx is a frequent radiographic finding in Standardbred horses. These lesions are routinely removed prior to the onset of a racing career with no evidence to support the timing of this surgical intervention.

OBJECTIVES

To determine whether horses racing before surgery slowed as they approached surgery date and whether they speeded up after surgery. To investigate the factors affecting whether a horse raced after surgery and compare the performance of horses that did and did not race before surgery.

STUDY DESIGN

A retrospective study using 193 Swedish Standardbred trotters.

METHODS

Medical records and radiographs of each horse were examined. Racing data were retrieved from official online records. Generalising estimating equations were used to examine presurgery racing performance and determine whether this differed between horses that raced before surgery and those that had not. Multivariable regression was used to examine career earnings and number of career races.

RESULTS

Horses racing before surgery neither slowed as they approached surgery, nor speeded up after surgery. Race speed of horses raced before surgery was not different from those that only raced after surgery. Racing before surgery was not associated with whether horses raced following surgery. Only horses with 3 affected legs had slower race speeds than other horses. No other horse level variables affected race speed, number of career races, career earnings or top speed.

CONCLUSIONS

There was no significant difference in race speed between horses that raced before surgery and those that did not. Horses did not slow down prior to surgery. Horses with 3 affected legs ran slower than those with only a single or 2 affected limbs. There was no association between timing of surgery and race speed or career longevity. The potential benefits of surgical intervention should be critically examined.

Genetic correlations for foal and studbook traits with racing traits and implications for selection strategies in the Finnhorse and Standardbred trotter

Genetic correlations for body measurements and conformation and functional traits in foals and studbook horses with racing traits were estimated in the Finnhorse and Standardbred. Genetic response and accuracy were estimated using records of animal, half-sibs and parents in selection scenarios for racing traits, for foal and racing traits, for studbook and racing traits, and using records of animal, half-sibs and parents for foal traits and racing traits of parents. Racing time and earnings were the breeding objective. Low-to-moderate genetic correlations for body measurements and racing traits indicated that selection favours bigger horses at all ages. Being mainly favourable for the breeding objective, genetic correlations for conformation and functional traits with racing traits were highest for the foal traits of type, trot and overall grade and for the studbook traits of character and movements. Genetic correlations for foal and studbook conformation with racing traits were low in the Finnhorse and moderate to high in the Standardbred. In foals, the highest genetic correlations were for trot with racing time (-0.54) and with earnings (0.52) in the Finnhorse, and for overall grade with racing time (-0.54) and with earnings (0.54) in the Standardbred. In studbook horses, genetic correlations were high for character with racing time and earnings in the Finnhorse (-0.68, 0.61) and in the Standardbred (-0.63, 0.70), and for movements with racing time and earnings in the Finnhorse (-0.70, 0.69) and in the Standardbred (-0.90, 0.88). To increase accuracy of conformation and functional traits, foal traits would be more useful in the index with racing traits, as being less preselected than studbook traits. The foal traits (type, trot, overall grade) having moderate heritability and genetic correlations with racing traits would be useful in multi-trait index before a racing career, where the greatest gain is because of a shorter generation interval. It would be feasible to implement for AI stallions.

Relationship between biochemical markers and radiographic scores in the evaluation of the osteoarticular status of Warmblood stallions

Establishing the osteoarticular status of the horse is often performed by means of radiological screening of the animals. Widespread blood sampling could reveal to be an interesting alternative to this procedure which is time consuming and sometimes technically difficult. The aim of this study was to investigate the relationship between the radiological status of the horses and the levels of biochemical markers of cartilage degradation and synovial inflammation. A specific radiological scoring and classification system was therefore developed and applied on 63 stallions presented for studbook admission. Additionally, groups of horses were established according to the occurrence of osteochondrosis, degenerative joint disease and distal interphalangeal joint effusion. Insulin growth factor-I, myeloperoxidases, Coll2-1 and Coll2-1NO(2) were used as blood markers. The combination of the blood parameters did not seem to correlate with the used scoring system. Coll2-1NO(2) levels however tended to increase with poorer radiological class and this could therefore potentially be a useful predictor of the osteoarticular status in the horse. Coll2-1 levels were significantly higher in the degenerative joint disease group. A high percentage of horses with distal interphalangeal joint effusion was present in this study and was associated with decreased IGF-I and increased Coll2-1 levels.