Thoroughbred Research Articles

Studies on embryonic development in thoroughbred mares

This study was planned to determine the embryonic developments in 12 Thoroughbred mares. The follicular growths were recorded in mares from day 8 postpartum till ovulation daily by using ultrasound machine with 7.5 MHz transrectal probe. All mares which were detected with largest follicle size and a characteristic uterine pattern of edema (cart-wheel like appearance) were mated with stallion every second day. Ultrasonography was carried out daily from day 14th post-mating till day 40 (ovulation = day 0) for detection of early of pregnancy and to monitor the conceptus. Embryonic vesicle was observed for the first time on day 14 in all mares with mean size of 10.25±0.59 mm. The fixation of vesicle, loss of spherical shape of vesicle, detection of embryo, detection of heart beats, detection of allantoic sac and start of fetal ascent were observed on 16.75±1.52, 20.66±1.86, 25.08±2.23, 28.16±2.45, 27.83±2.43 and 27.83±2.43 days post-mating, respectively. It was concluded that ultrasonic detection of early pregnancy and embryonic developments studies is an accurate tool and simple way for estimating the age of pregnancy in Thoroughbred mares.

Case Report of Equine Influenza in Italy, in 2014

Equine influenza (EI) is a highly contagious respiratory disease presently caused by subtype H3N8. As no active surveillance is ongoing in Italy, clinical observations of veterinary practitioners would indicate the infection as endemic. This study reports the isolation and genetic characterization of an EI virus (EIV) from a stable of Thoroughbred race horses. The episode was characterized by fever and dry cough and involved eleven, 2- to 3-year-old, flu vaccinated horses, four of which were found positive for EIV, by reverse-transcriptase real-time polymerase chain reaction (RRT-PCR) targeting the matrix gene. The EIV of two of the four RRT-PCR positive samples was successfully passaged in embryonated chicken eggs. Analysis of amino acid (AA) sequences of hemagglutination (HA) residues detected seven substitutions in the Italian isolate when compared with the prototype strain A/eq/Richmond/1/2007 (H3N8 American lineage, Florida clade 2). The constructed phylogenetic tree locates the present strain within the Florida clade 2, together with viruses isolated between 2011 and 2014 in Algeria, China, Eire, Germany, Japan, Mongolia, and the United Kingdom. Within this cluster, the Italian isolate presents 100% AA identity with A/eq/North Rhine Westphalia/1/2014, responsible of an outbreak in Germany around the same period. Even if vaccinated, only two of the 11 clinically involved animals, different from the EIV-positive animals, reacted positive in HA inhibition. Monitoring of the circulating strains of EIV is essential especially for verifying the appropriateness of the vaccine virus composition, as recommended by the OIE Panel of experts, on the basis of the genetic and antigenic characteristics of emerging strains.

Topografia dos vasos sanguíneos arteriais e venosos nos rins de Cavalos Puro Sangue Inglês

<p>As doenças renais em equinos, geralmente estão associadas a problemas respiratórios e digestórios, entretanto não são frequentes as intervenções cirúrgicas neste órgão para estes animais. O estudo dos vasos sanguíneos relativos aos rins nos animais domésticos e selvagens é de fundamental importância para o entendimento de diversos aspectos de sua fisiologia e nutrição. Neste trabalho, foram utilizados 30 pares de rins de equinos Puro Sangue Inglês, dos quais 15 machos e 15 fêmeas, de diferentes faixas etárias, provenientes de doação do Jockey Club de São Paulo. Durante a necropsia dos animais, os rins unidos por meio de suas artérias e veias renais foram retirados em bloco. Em seguida, foram fixados em solução de formol a 10%, por aproximadamente 48h, para a dissecação e individualização dos componentes dos pedículos renais. Para a análise dos resultados foram demarcados os quadrantes cranioventral, craniodorsal, caudoventral e caudodorsal, com duas linhas uma craniocaudal e a outra dorsoventral. Os resultados obtidos revelaram que: os ramos arteriais da região hilar são observados no rim direito em número de dois em 50%, no esquerdo em número de dois (33,3%), os ramos arteriais na região justahilar são computados no rim direito em número de quatro a cinco em 20% e no rim esquerdo em número de seis (16,7%), e nos ramos dispostos na região extrahilar são registrados no rim direito em número de três (26,7%) e no esquerdo em número de três (20%).</p>

Crossbreed genetic performance study in the eventing horse competition

Eventing is an equestrian discipline combining dressage, show jumping and cross-country exercises. The Spanish Sport Horse (SSH) was used in this study as an example to develop a method to ascertain the influence of parental breeds on particular performances by linking their parental genetic contribution with the individual phenotype value computing the optimal breed contribution for each trait evaluated in eventing. Data included 1220 eventing records from 210 SSH animals. The genetic contribution of six main founder populations were computed for each SSH: the Spanish Purebreed (SPB), Arab Horse (A), Thoroughbred (TB), Selle Français (SF), German breeds (G) and North(-west) European (N) breeds. For this analysis we used BLUP (best linear unbiased predictor) animal models for five defined traits and for the total score. The genetic contribution as linear and quadratic adjustment and the interaction between genetic contributions were included as covariates in the genetic model to separate the possible combining ability from the breeding values. The optimal breed genetic contribution for each trait was maximised by using a simplex method. The best combination for conformation was 51% SPB and 49% N, for cross-country aptitude 23% SPB and 77% N, for dressage 48% SF and 52% N, and for show jumping 64% A and 36% N. For cross-country the best performance was predicted using 100% N genetic contribution and for the total score of 24% SF and 76% N. The combination of two breeds (group of breeds) seemed to be the best option for most of the traits. Although the results should be interpreted with caution, the importance of this paper is that it can be considered as a starting point of the analysis. The methodology applied here performed nicely in searching for the best contribution of several breeds to find the best combination for particular interests and could, therefore, be useful for other species/populations.

Non-fatal injury occurrence in Southern California Thoroughbred racehorses 2009–2010

Private-practice racetrack veterinarians in southern California recorded non-fatal injuries meeting defined criteria in Thoroughbreds for 1 year. Injury incidence was 2.29 injury events per 100 horse-months, which was lower than other studies where trainer reported injury data were collected. Of 477 injuries recorded, 344 (72.1%) were acute and 133 (27.9%) were chronic. Fractures were common (47.6% of injuries), with stress fractures accounting for 14% of injuries. Superficial digital flexor tendonitis and suspensory ligament desmitis accounted for 15.3 and 11.5% of injuries, respectively. Agreement between non-fatal injuries recorded in the current study and those recorded via an existing regulatory system (Equine Injury Database) was poor, with neither system capturing all injuries. Non-fatal injuries occurred 17–29 times more often than fatal injuries. Non-fatal musculoskeletal injury remains an ongoing issue for Thoroughbred racehorses, and an accurate, comprehensive system for recording these injuries is needed.

Are results of Crib Opening Test connected with efficacy of training horses in a round-pen?

Training the horse is based on human–horse relationship, which requires that the horse shows active, conscious behaviour as well as an ability to learn. It was hypothesized that the horse's learning skill to open the crib is correlated with the effectiveness of training. The aim of the study was to find out whether there is a relationship between the time needed for a naïve horse to open the crib and to accomplish first saddling and mounting. 120 horses were examined: 40 Thoroughbreds (TB), 40 Purebred Arabians (PA), and 40 halfbred Angloarabians (AA). There were 20 colts and 20 fillies in each breed group. The times needed by the horse to open the crib (Crib Opening Test) were assumed as a measure of an aspect of learning skill. The effectiveness of the initial training of the horse was evaluated by the times needed to first saddling and mounting the naïve horse (Saddling Test and Mounting Test) as well as by heart rate (HR) and heart rate variability (HRV) in Saddling Test and Mounting Test. Horse behaviour during the tests was assessed.It took the TB horses significantly longer to open the crib than it took the AA horses (306s vs 191s, respectively). Numerous statistically significant correlations were found between the results of Crib Opening Test and the results of Saddling Test performed by the TB fillies and AA horses: positive with HR, and negative with some HRV parameters. Correlations between the results of Crib Opening Test and Mounting Test were negative with HR and positive with beat-to-beat time (RR) for the PA and AA fillies. It seems that the horses which quickly succeed in Crib Opening Test are calm during the first phase of the initial training until saddling, but they do not willingly accept mounting. However, the relationship between the time of opening the crib and response to the training should be analysed separately in particular horse breeds and sexes.

The role of catastrophic injury or sudden death of the horse in race-day jockey falls and injuries in California, 2007-2012.

If equine conditions with high likelihood of jockey injury can be determined and subsequently prevented, jockey safety can be enhanced. To identify racehorse injuries or conditions with greatest risk for jockey falls and injuries. Retrospective correlation of race-day jockey fall and injury data with racehorse fatality data. Thoroughbred (TB) and Quarter Horse (QH) racehorse cause of death and jockey fall and injury data for California flat races were reviewed for a 6-year period. Race and jockey race ride population data were used to determine jockey fall and injury incidence rates relative to cause of racehorse death, and were assessed using Poisson regression. Differences in proportions were assessed using Fisher's exact, Pearson's χ(2), and Cochran-Mantel-Haenszel tests. 707 racehorses experienced race-related catastrophic injury or sudden death. 199 jockeys had 601 falls with 325 injuries. Jockeys were 162 times more likely to fall (95% confidence interval 137-192; P<0.001) and 171 times more likely to be injured (95% confidence interval 140-208; P<0.001) when they rode a horse that died in a race. We infer that jockeys were more likely to fall or be injured when riding in QH races than in TB races because of a higher incidence of horse fatalities in QH races. Jockey falls occurred with 24% of TB and 36% of QH race-related horse fatalities, and jockey injury occurred in 64% of falls. Jockey falls were most common with TB fetlock injuries and QH carpal, metacarpal and fetlock injuries; and with axial, bilateral and multiple injuries compared with appendicular, unilateral and singular injuries, respectively. Prevention of the most common catastrophic injuries and conditions of the racehorse, e.g. fetlock injuries, may be most effective at decreasing rates of falls and injuries to horseracing jockeys during racing.

Prevalence of Radiographic Abnormalities of the Proximal Interphalangeal Joint of Young Thoroughbreds and Associations With Early Racing Performance

Radiographic abnormalities (RAs) in the proximal interphalangeal (pastern) joint have several manifestations and can cause concern in young horses intended for racing. Our objective in this retrospective study was to describe the appearance and prevalence of pastern RAs in young Thoroughbreds and compare the racing outcomes of cases with sibling controls. All radiographic reports of young Thoroughbred racehorses born in 2003–2007 read by veterinarians in one Lexington, Kentucky, practice were searched for pastern RAs. Pastern RAs are described, and the 2- and 3-year-old racing records of affected horses are compared with siblings. Pastern RAs were detected in 1.3% of weanling and yearling Thoroughbred horses examined. Radiographic abnormalities detected included shallow (≤3 mm) indentations in joint contour, dorsal osteophytes or axial palmar and/or plantar enthesophytes (≥3 mm), osseous fragments, and subchondral lucencies (≥4 mm). Horses with fragments in the pastern joint tended to be less likely to start a race at 2 years of age. Horses with fragments and subchondral bone cysts in the distal first phalanx tended to be less likely to start a race at 2 or 3 years of age than control siblings. The importance of some pastern joint RAs to performance can be overemphasized; however, some RAs have a tendency to be associated with poorer racing outcomes than sibling controls and may be considered when reviewing the radiographs of young Thoroughbred racehorses.

The Effect of Race in the Clinical, Hematological and Biochemical Biomarkers in Thoroughbred Horses

Thoroughbred horse racing is a worldwide sport and industry involving the racing of Thoroughbred horses. It is governed by different national bodies. There are two forms of the sport: flat racing and jump racing. So the study the clinical, hematological and biochemical biomarkers are most useful information that make the race horse such a super athlete and good managed. This study was carried out on twenty one thoroughbred race horses in order to evaluate physical performance and recovery time through measuring the clinical parameters ( Heart rate, Respiratory rate, Body temperature and capillary refilling time ) , hematological ( RBCs, PCV, Hb, total and Differential leucocytic count) and biochemical biomarkers ( TP, Albumin, AST, ALT,CK,LDH, Lactic acid, Glucose, Cholestrol,Na, K, Cl and Urea , Creatinine, Ca, P and Mg ). Clinical and blood samples were occurred just before and at 5, 15 and 60 minutes after 1600 meter race. The results showed significant increase in all clinical and hematological and biochemical biomarkers 5 min after end of exercise and returned to basal levels after 60 minutes rest. The results can be useful index about horse performance, the effect of race on horse metabolism and helpful in management protocols of athletic horses during training under hot climate conditions.

Do vendors value safety in Thoroughbred horses in the Australian recreational riding horse market?

Abstract The purpose of this short report is to describe the influences on the pricing of Thoroughbred (TB) horses for the adult recreational riding market. Research into the association between horse breed and specific behaviors supports the view that some breeds are more reactive than others. There is anecdotal evidence that TBs may be more likely than other breeds to show traits that compromise rider safety. Having been bred for speed and reactivity, TBs may have reduced habituation tendencies. In addition, those that have raced may have had more training to accelerate than to decelerate and as such may be predisposed to uncontrollable flight responses. We examined data from advertisements to determine which descriptors influence the price of TBs (n = 220) entering the adult riding horse market. Linear regression analysis of log(price) revealed that variates such as a larger total sum of performance experience and bigger advertisements ( P P P = 0.002). The inclusion of positive descriptive terms associated with safety had a rather smaller and less significant effect ( P = 0.012) on price. The average advertised price of $3,286 for a TB was significantly cheaper than the average advertised price of a non-TB horse ($7,384; P

Prevalence, location and symmetry of noncatastrophic ligamentous suspensory apparatus lesions in California Thoroughbred racehorses, and association of these lesions with catastrophic injuries.

Knowledge of the site distribution of ligamentous injuries facilitates clinical diagnosis of suspensory apparatus conditions. To determine if lesions within the suspensory ligament (SL) and distal ligaments of the proximal sesamoid bones (DSLs) were associated with suspensory apparatus failure or metacarpal lateral condylar fracture in California Thoroughbred racehorses. Cross-sectional study. Suspensory apparatus specimens from 327 deceased Thoroughbred racehorses were sectioned within the SL body and branches, and oblique and straight DSLs. Purple lesions ≥2 mm in width were categorised as moderate and paler or smaller lesions as mild. Associations between moderate lesions and age, sex, racetrack and cause of death were evaluated using multivariable logistic regression. Moderate lesions were evident in 16% and milder lesions in 77% of racehorses. Moderate lesions occurred with similar frequency in SL branches and oblique DSLs. Moderate lesions were more likely to occur in horses that died as a result of suspensory apparatus failure (odds ratio [OR] = 4.60; 95% confidence interval [CI] 1.61-13.13; and P = 0.004) or metacarpal lateral condylar fracture (OR = 5.05; 95% CI 1.42-17.93; and P = 0.012) compared with horses that died from nonmusculoskeletal causes, and in horses aged ≥7 years horses compared with 2-year-old horses (OR = 5.33; 95% CI 1.44-19.75; and P = 0.012). Moderate lesions are common in the SL branches and oblique DSLs of racehorses, and may be associated with risk for suspensory apparatus failure and metacarpal condylar fracture. Monitoring health of the suspensory apparatus ligamentous structures may be a simple means of assessing fatigue in, and preventing more extensive injuries to, the forelimb suspensory apparatus and metacarpal condyles.

Doppler Ultrasonographic Estimation of Renal Resistive Index in Horse: Comparison Between Left and Right Kidneys

The renal resistive index (RI) is the ratio of the difference between maximum and minimum (end diastolic) flow velocity derived from the Doppler spectrum of intrarenal (segmental/interlobar) arteries. It is a good indicator for acute renal disease, acute tubular necrosis, and renal obstruction. To our knowledge, no reports are available about the values of renal RI in unsedated horses. The aim of this study was to establish a normal reference range (mean ± standard error) and to assess the reliability of the renal RI obtained using transabdominal ultrasonography in unsedated healthy horses. Thirteen conscious Thoroughbred horses judged healthy based on physical examination, complete blood count, biochemical profile, urinalysis, and ultrasonography were included. The peak-systolic and end-diastolic velocities of interlobar and arcuate arteries were measured. Intrarenal arteries were scanned by pulsed Doppler ultrasonography to calculate RI. The comparison of left versus right kidneys was analyzed with analysis of covariance (ANCOVA) procedure. Significant differences (P < .05) for the RI values were observed between left and right kidneys in the geldings (left 0.50 vs. right 0.56) and mares (left 0.50 vs. right 0.57) and were observed between left and right kidneys in trained (left 0.52 vs. right 0.55) and untrained horses (left 0.48 vs. right 0.58). The renal RI has not been modified by sex.

Effectiveness of training programmes used in two stables of thoroughbred race horses

The purpose of this study was to compare the training methods used in two stables and their effects on selected blood parameters and race results. A total number of 36 thoroughbred race horses was examined in two groups, trained by two trainers. Twenty-four horses (group A) were trained at Sluzewiec and the remaining twelve horses (group B) were kept and trained in a private stable. The experiment lasted for five months. The activities of CPK (creatine phosphokinase) and AST (aspartate aminotransferase) and the concentration of LA (lactic acid) were determined. The speed was controlled and recorded by a Garmin GPS system. The analysis of the General Handicap rating demonstrated that the training methods used in stable A were more effective and resulted in better classification of these horses. Training methods in both stables were evaluated and compared on the basis of maximal speeds during training sessions and related post exercise LA concentrations. The main differences between training methods used in both stables concerned the workload and the time of work with the rider. Analysis of the values measured in individual horses from stable B have shown that AST and CK activities were high not only in all young, 2-year-old horses but also in three older ones. This seems to confirm the lack of balance and proper movement coordination in these horses, resulting in high activities of muscle enzymes.

Therapeutic Shoeing for Spontaneous Quarter Cracks Induced by Sheared Heel in Thoroughbred Race Horse

A 3-year-old colt Thoroughbred horse was referred with obvious lameness (3/5G) and mild heat and pain on left hoof of forelimb. He was diagnosed with quarter cracks that have a typical conformation of sheared heel, which are a different length and height between medial/lateral heels. Various materials and techniques were carried out to repair quarter cracks by using many different kinds of clips, bar shoes on fifth times for about 10 months. It worked on him without pain and heat on the cracked hoof, and then he could retrain for racing from the 36th weeks beginning of therapeutic shoeing. We suggested that especially fiberglass reinforced plastic (FRP) material and therapeutic shoeing were a great help to treat quarter cracks induced by sheared heel.

Long-Term Follow-up of Superficial Digital Flexor Tendonitis Treated by a Single Intralesional Injection of a ReGeneraTing Agent in 51 Horses

ReGeneraTing Agents (RGTA) are nanopolysaccharides engineered to mimic heparan sulfates and have been shown to stimulate tissue repair and healing (skin, cornea, gingival, and muscle) in several animal models of injury and in human medicine. A preliminary study, monocentric and uncontrolled, was conducted to evaluate the efficacy of a dedicated RGTA (named Equitend) in improving the healing quality of the injured tendon after a single and ultrasound-guided intralesional injection. Improvement of ultrasonographic appearance of tendinous or ligamentous lesion was documented at least over 4 months in Equitend-treated horses and was further supported by another study on superficial digital flexor tendonitis, in 51 horses (16 French Standardbred trotters (ST), 13 Thoroughbreds (TB), and 22 eventers). Long-term follow-up of these horses showed high rates of return to racing, with 95% of eventers, 87.5% of French ST, and 77% of TB. The mean duration before the first race or competition was 6.6 and 7.4 months for ST and eventers, respectively. The group of 16 treated ST was then compared with a matched control group, showing that the Equitend-treated group was able to return to a higher level of earning after lesion (74% vs. 15% in the control group). Furthermore, the Equitend-treated group was back in racing 2.4 months earlier than the control group.

Prevalence of stereotypies in thoroughbred race horses at Club Hípico Concepción, Chile

ABSTRACTObjective. To determine the prevalence of classic stereotypies in Thoroughbred racehorses at the Club Hípico Concepción (CHC) in Chile and its association with sex and age. Materials and methods. The entire population of resident horses at the CHC was studied (n=341). Each horse trainer (n=23) was asked for the name, sex and age of the horses under his/her supervision. After that, all the animals were continuously observed inside their stalls for 8 hours by only one person, to record the absence or presence of classic stereotypies (cribbing, weaving, stall-walking). To analyze the data, the animals were divided by sex into 3 groups: stallions, geldings and mares. According to age, they were divided into 2 groups: &lt; 5 years old and 5 years old or more. Descriptive statistics were used and association was tested using the chi square test using p≤0.05. Results. 13.2% of all CHC’s horses displayed stereotypies: cribbing (4.99%), weaving (2.93%) and stall-walking (5.28%). No association was found between the presence of stereotypies and sex or age. Conclusions. Thoroughbred race horses at the CHC showed a high prevalence of classic stereotypies, especially stall-walking.

Disposition and metabolic profile of the weak androgen Dehydroepiandrosterone (DHEA) following administration as part of a nutritional supplement to exercised horses.

In order to ensure the welfare of performance horses and riders as well as the integrity of the sport, the use of both therapeutic and illegal agents in horse racing is tightly regulated. While Dehydroepiandrosterone (DHEA) is not specifically banned from administration to racehorses in the United States and no screening limit or threshold concentration exists, the metabolic conversion of DHEA to testosterone make its presence in nutritional supplements a regulatory concern. The recommended regulatory threshold for total testosterone in urine is 55 and 20 ng/mL for mares and geldings, respectively. In plasma, screening and confirmation limits for free testosterone (mares and geldings), of no greater than 0.1 and 0.025 ng/mL, respectively are recommended. DHEA was administered orally, as part of a nutritional supplement, to 8 exercised female thoroughbred horses and plasma and urine samples collected at pre-determined times post administration. Using liquid chromatography-mass spectrometry (LC-MS), plasma and urine samples were analyzed for DHEA, DHEA-sulfate, testosterone, testosterone-sulfate, pregnenolone, androstenedione, and androstenediol. DHEA was rapidly absorbed with maximal plasma concentrations reaching 52.0 ± 43.8 ng/mL and 32.1 ± 12.9 ng/mL for DHEA and DHEA sulfate, respectively. Free testosterone was not detected in plasma or urine samples at any time. Maximum sulfate conjugated testosterone plasma concentrations were 0.98 ± 1.09 ng/mL. Plasma testosterone-sulfate concentrations did not fall below 0.1 ng/mL and urine testosterone-sulfate below 55 ng/mL until 24-36 h post DHEA administration. Urine testosterone sulfate concentrations remained slightly above baseline levels at 48 h for most of the horses studied.

Use of Standing MRI and a New MRI Grading System of the Subchondral Bone of the Distal Third Metacarpal Bone to Identify Bone Changes in the Thoroughbred Racehorse When Comparing 21 Cases of Catastrophic Biaxial Proximal Sesamoid Bone Fracture with 53 Controls

Reasons for performing studyBiaxial fracture of the proximal sesamoid bones (PSB) is the leading cause of fetlock failure resulting in euthanasia in Thoroughbred racehorses in California, Kentucky and Hong Kong. Identifying alterable risk factors to reduce biaxial PSB fractures could have a significant impact on reducing the occurrence of catastrophic failure of the fetlock (CFF).ObjectivesWe hypothesised that standing MRI (sMRI) would identify a greater degree of bone change in Thoroughbred racehorses with CFF from biaxial PSB fracture when compared to controls.Study designRetrospective cohort study.MethodsBone changes from Florida Thoroughbred racehorses with CFF due to biaxial fracture of the PSB (n = 21) were compared to controls (n = 53) using the sMRI. Data for control limbs were Florida racehorses that were subjected to euthanasia for reasons other than CFF (enteritis, pneumonitis, etc.). All forelimb fetlocks underwent sMRI imaging within 72 h of euthanasia. Bone scores were assigned to the subchondral bone (SCB) on the distal palmar aspect of the lateral and medial condyle of the third metacarpal bone (McIII) and the lateral and medial PSB. All information for analysis from sMRI images for cases and controls for all Thoroughbred racehorses was reviewed and collected by the lead author. The association between the dichotomous outcomes of PSB fracture with independent variables was assessed using bivariable and multivariable logistic regression analysis with significance set at P&lt;0.05.ResultsThe proportion of cases with &gt;75% sclerosis of the ipsilateral lateral PSB (43%, 9/21) was significantly greater than that among controls (6%, 3/53). The proportion of cases with SCB lesion grade &gt;3 of the contralateral palmar lateral condyle (29%, 6/21) was significantly greater than that among controls (0%, 0/53).ConclusionsThe sMRI identified a significantly greater degree of bone change in racehorses with PSB fracture compared to control horses. These identified changes may be useful as a screening tool to identify horses at increased risk of fetlock fracture during racing.Ethical animal research: Explicit owner informed consent for participation in this study was not given but permission for post mortem examination was given by the Racing Authority. Sources of funding: None. Competing interests: No competing interests have been declared.

Pharmacokinetics and Bioequivalance of Five Commercially Available Formulations of Omeprazole: A Preliminary Report

Reasons for performing studyThe pharmacokinetics and bioequivalence of different formulations of omeprazole have not been published.ObjectivesTo compare the pharmacokinetics and bioavailability of 4 commercially available formulations of omeprazole to an existing reference formulation.Study designA single dose cross‐over bioequivalence study.MethodsSix adult Thoroughbred horses were used. Two generic buffered formulations (OG and AG), one commercial enteric coated formulation (GZ) and one compounded enteric coated formulation (BO) were compared to the reference buffered formulation (GG). Each formulation was administered at a total dose of 2 g (equivalent to 4 mg/kg bwt for a 500 kg horse) in a cross‐over design. Blood samples were collected at 0, 15, 30, 45, 60, 75, 90, 105, 120, 150, 180, 210, 240, 300 and 360 min, the plasma was separated and frozen. Plasma omeprazole concentrations were determined by UPLC‐MS. Noncompartmental pharmacokinetic analyses were performed using PK Solver.ResultsThe mean (± s.d.) area‐under‐the‐curve (AUC0‐t/0‐inf_obs) (μg/ml*min), Cmax (μg) and Tmax (min) for each formulation was; OG – 59.4 ± 20.1, 0.37 ± 0.12, 87.5 ± 38.4; AG – 77.3 ± 53.7, 0.34 ± 0.24, 170.0 ± 62.0; GZ – 102.9 ± 51.1, 0.86 ± 0.68, 67.5 ± 29.6; BO – 88.0 ± 37.4, 0.59 ± 0.39, 95.0 ± 47.1; GG – 57.5 ± 35.3, 0.41 ± 0.22, 57.5 ± 19.9.ConclusionsThe results of this study suggest that differences are present between commercially available formulations of omeprazole. Caution should be exercised in extrapolating results of clinical studies from one formulation to another.Ethical animal research: This study was performed under an ethics permit issued by the NSW Department of Primary Industries and in accordance with relevant state laws and legislation. Explicit owner informed consent for participation in this study was not stated. Sources of funding: This study was funded by a grant from the Grayson‐Jockey Club Research Foundation. Competing interests: The manufacturers of Gastrozol (GZ), Abgard (AG) and BOVA (BO) have previously funded research by B.W. Sykes. None of the companies contributed to the present study.

Haplotype diversity in the equine myostatin gene with focus on variants associated with race distance propensity and muscle fiber type proportions.

Two variants in the equine myostatin gene (MSTN), including a T/C SNP in the first intron and a 227-bp SINE insertion in the promoter, are associated with muscle fiber type proportions in the Quarter Horse (QH) and with the prediction of race distance propensity in the Thoroughbred (TB). Genotypes from these loci, along with 18 additional variants surrounding MSTN, were examined in 301 horses of 14 breeds to evaluate haplotype relationships and diversity. The C allele of intron 1 was found in 12 of 14 breeds at a frequency of 0.27; the SINE was observed in five breeds, but common in only the TB and QH (0.73 and 0.48 respectively). Haplotype data suggest the SINE insertion is contemporary to and arose upon a haplotype containing the intron 1 C allele. Gluteal muscle biopsies of TBs showed a significant association of the intron 1 C allele and SINE with a higher proportion of Type 2B and lower proportion of Type 1 fibers. However, in the Belgian horse, in which the SINE is not present, the intron 1 SNP was not associated with fiber type proportions, and evaluation of fiber type proportions across the Belgian, TB and QH breeds shows the significant effect of breed on fiber type proportions is negated when evaluating horses without the SINE variant. These data suggest the SINE, rather than the intron 1 SNP, is driving the observed muscle fiber type characteristics and is the variant targeted by selection for short-distance racing.