Exercise is one of the most common stressors in horses. Although various physiological parameters such as cortisol respond to exercise, there is no reliable parameter for the measurement of exercise-induced stress in sport horses. This study was performed to discover a new biomarker with high sensitivity for exercise-induced stress. The expression of fos mRNA was increased more than 10-fold in horse blood samples collected after an hour of exercise, as compared with before the exercise. The plasma cortisol levels were also increased after the exercise, but only by about two-fold. The fos mRNA levels were well-correlated with plasma cortisol concentrations. These findings suggest that fos mRNA expression in blood may be useful for the measurement of exercise-induced stress in horses.

To establish the protocol of a standardized exercise test for evaluating exercise intolerance and degree of fitness in Thoroughbred racehorses, we examined serum lactate concentrations related to exercise intensities using the high speed tradmill. Twelve clinically healthy Thoroughbred racehorses with or without previous training or racing history were assigned to two groups, fit and unfit group, respectively. The protocol used for the standardized exercise test was consisted of two stages:stage ofwarm-up and that of acceleration. During the warm-up, the horses exercised 5 min at 1.8m/s and 3 min 3.4m/s without inclination. At the acceleration stage, exercise test was performed at 10% slope and the speed was increased from the initial 5m/s to the maximal speed which each tested horse could keep up with. The speed was increased with incremental steps of 1 m/s every minute. During the last 15 sec of each step, blood samples were collected for serum lactate determination. V max (masimal treadmill speed which tested horses could keep up with) of the fit group (10.93+_0.33m/s, mean+_SE, n=6) was higher than that of the unfit group (9.52+_0.23m/s, mean+_SE, n=6). Serum lactate concentrations increased exponentially according to exercise intensities. V la4 (speed producing a serum lactate concentration of 4mmol/l) of the fit group, 6.45+_0.26m/s, was higher than that of the unfit group, 5.45+_0.23m/s. La peak (peak plasma lactate concentration during the exercise test) was lower in the fit group (20.34+_1.62mmol/l at 1 min after maximal intensity exercise) than in the unfit group (24.78+_1.09mmol/l at 2 min after maximal exercise step). t50% (time required for the recovery of lactate concentration to be one-half of La peak after maximal exercise) of the unfit group and the fit group were 40.0 and 18.0 min, respectively. Therefore, the protocol of the incremental standardized exercise test utilized in this study seems to be reliable for the assessment of fitness and exercise intolerance for the Thoroughbred racehorses.

The present study was carried out to investigate the blood markers of Cheju horses. The red cell types (blood groups) were tested from 73 Cheju native horses and 118 Cheju racehorses by serological procedures with 23 reagents. The blood group phenotypes observed with high frequency were Pb(34.3%), Qc(56.2%), Qb(15.1%) and genotypes Dbcm/dghm(12.3%), Dde/dghm(9.6%), Dad/bcm(6.8%), Dcgm/de(6.8%) in Cheju native horses, while Aa(63.6%), Pa(44.9%), P-(28.8%), Qabc(36.4%), Dbcm/cgm(14.4%), Dbcm/bcm(10.2%), Dbcm/de(7.6%), Dbcm/dghm(5.1%), Dde/dk(5.1%) in Cheju racehorses. Alleles observed with high frequency were Ab(0.128), Ac(0.169), Dad(0.103), Dadn(0.075), Ddghm(0.226), Pb(0.316), Qc(0.494) in Cheju native horses and Aa(0.529), Dbcm(0.306), P-(0.531), Qabc(0.197), Q-(0.504) in Cheju racehorses. No specific variation of blood groups and allele frequencies of C, K, U system were observed in Cheju native horses and Cheju racehorses. The mean heterozygosity in Cheju native horses and Cheju racehorses was observed 0.5344 and 0.5102, respectively.

The disease causing colic is the greatest cause of deathe in the domestic horse population today and accidental deaths as a result of colic leads to decreased productivity and economic losses in the horse breeding industry. Large colon impaction is the most common cause of colic in horses. Horses may ingest sand either by eating from the ground in sandy locations, or because of its inclusion in hay. In certain areas sand impaction is relatively common. The horse (4 year, female) presented with abdominal pain, which was charactered by willing to lie down, pawing, and looking at flank. A month later, the horse died suddenly at sand paddock.

The fused and deformed lumbar vertebrae (L) of Thoroughbred horses were observed macroscopically. Results revealed five L in two cases, and six L in three cases. In two cases, the last two lumbar vertebrae were fused with each other. One case of the fused lumbar vertebra was observed in a horse with five L and the other in that with six L. In one case, the facet of second last lumbar vertebra was articulated with its anterior lumbar vertebra. On the other hand, four cases had the caudal border on the lateral tip of the lumbar transverse process partially overlapped with the cranial border of the following lumbar transverse process. In these cases, cranial and caudal tubers were formed on the overlapped part of the lumbar transverse process.

The prevalence of antibody to Getah virus was serologically followed among those horses in Korea. Blood samples were taken from 575 horses in Feb and 462 horses in Sep. 1985. Overall percentage of horses with seropositive to Getah virus was 37% in Feb and 47% in Sep. The data suggest that the Getah virus infection was endemic in Korea and the increase in prevalence may be associated with the seasonal activity of arthropod vectors. This entails preventive precautions of the horses against this viral infection before the entry into Korea