Abstract: REASONS FOR PERFORMING STUDY: One cause of overstrain injury to the superficial digital flexor tendon (SDFT) in horses is the force loaded on the SDFT during repeated running. Therefore, decreasing this force may reduce SDFT injury. It has been reported that strain on the SDFT decreases with a toe-wedge shoe. Uphill courses are used for training of racehorses, and the angle of hoof-sole to the horizon during uphill running is similar to that of the toe-wedge shoe. OBJECTIVES: To determine the effects of uphill exercise on the force on the SDFT during trotting and cantering. METHODS: Arthroscopically implantable force probes (AIFP) were implanted into the SDFT of the left or right forelimb of 7 Thoroughbred horses and AIFP output recorded during trotting and cantering on a treadmill inclined at slopes of 0, 3 or 8%, and then 0% again. Superficial digital flexor tendon force was calculated as a relative value, with the amplitude of AIFP output voltage at initial 0% slope equal to 100. RESULTS: Out of 14 sets of experiments, AIFP data were analysed successfully in 9 at the trot, in 3 at the canter in the trailing forelimb on a slope of 3 and 8%, and in 2 at the canter in the leading forelimb on a slope of 3%. Increasing the incline from 0-8% tended to decrease peak force in the SDFT at the trot, and in the trailing forelimb at the canter. However, force in the SDFT was unchanged in the leading forelimb at the canter on the 3% incline. CONCLUSIONS: The force in the SDFT trotting or cantering uphill is unchanged or lower than that loaded at the same speed on a flat surface. Because at similar speeds the workload for uphill exercise is greater than on the flat, uphill running increases exercise intensity without increasing force in the SDFT. POTENTIAL RELEVANCE: Uphill exercise may reduce the risk of SDFT injury as both running speed and SDFT force are decreased on an incline as compared to the flat, even when exercise intensity is the same. Further study is needed to confirm these findings at canter in a larger population of horses.

Abstract: REASONS FOR PERFORMING STUDY: Short format 3-day events were introduced in 2004. Anecdotal reports suggested that horses were more tired on completion of the cross-country phase of short format events when compared with horses completing the cross-country phase of long format competitions, despite the absence of Phases A, B and C. OBJECTIVES: To compare the physiological parameters and haematological parameters of horses that had completed the cross-country phase of a short format (SF) and a long format (LF) CCI 2* competition. METHODS: During a CCI 2* competition 69 competitors took part in the short format and 74 in the long format competition. Long format competitors completed Phases A, B, C and D and short format competitors completed Phase D only. Phase D (the cross-country course) was identical for both competitions. Two-way ANOVA for repeated measures and post hoc tests were used to compare temperature, pulse and respiration rates of horses competing in both types of competition. T tests were used to compare mean lactate and electrolyte concentrations, while U-Mann Whitney tests were used to compare CK and AST levels measured in horses competing in the short and long formats of the event. RESULTS: Training schedules, age and previous competition experience were not significantly different between horses competing in the SF and LF competitions. On completion of Phase D, SF horses had significantly higher PCV and significantly lower ionised calcium concentrations when compared with LF horses. LF horses had significantly higher heart rates than SF horses 10 min prior to starting Phase D and immediately after completing Phase D; however, no other significant differences were found between the 2 groups of horses. CONCLUSIONS: Only weak evidence was found to support the hypothesis that the workload for the horse in a SF CCI 2* competition is significantly different when compared to the LF CCI 2* competition. POTENTIAL RELEVANCE: There is no beneficial or detrimental effect on horses that complete short format CCI 2* competitions as compared to those that complete long format CCI 2* competitions but further research is required into the physiological response of horses at CCI 3* and CCI 4* short format competitions.

Abstract: Non-invasive techniques to monitor stress hormones in small animals like mice offer several advantages and are highly demanded in laboratory as well as in field research. Since knowledge about the species-specific metabolism and excretion of glucocorticoids is essential to develop such a technique, we conducted radiometabolism studies in mice (Mus musculus f. domesticus, strain C57BL/6J). Each mouse was injected intraperitoneally with 740 kBq of 3H-labelled corticosterone and all voided urine and fecal samples were collected for five days. In a first experiment 16 animals (eight of each sex) received the injection at 9 a.m., while eight mice (four of each sex) were injected at 9 p.m. in a second experiment. In both experiments radioactive metabolites were recovered predominantly in the feces, although males excreted significantly higher proportions via the feces (about 73%) than females (about 53%). Peak radioactivity in the urine was detected within about 2h after injection, while in the feces peak concentrations were observed later (depending on the time of injection: about 10h postinjection in experiment 1 and about 4h postinjection in experiment 2, thus proving an effect of the time of day). The number and relative abundance of fecal [3H]corticosterone metabolites was determined by high performance liquid chromatography (HPLC). The HPLC separations revealed that corticosterone was extensively metabolized mainly to more polar substances. Regarding the types of metabolites formed, significant differences were found between males and females, but not between the experiments. Additionally, the immunoreactivity of these metabolites was assessed by screening the HPLC fractions with four enzyme immunoassays (EIA). However, only a newly established EIA for 5alpha-pregnane-3beta,11beta,21-triol-20-one (measuring corticosterone metabolites with a 5alpha-3beta,11beta-diol structure) detected several peaks of radioactive metabolites with high intensity in both sexes, while the other EIAs showed only minor immunoreactivity. Thus, our study for the first time provides substantial information about metabolism and excretion of corticosterone in urine and feces of mice and is the first demonstrating a significant impact of the animals' sex and the time of day. Based on these data it should be possible to monitor adrenocortical activity non-invasively in this species by measuring fecal corticosterone metabolites with the newly developed EIA. Since mice are extensively used in research world-wide, this could open new perspectives in various fields from ecology to behavioral endocrinology.

Abstract: The feeding and drinking behavior of 11 mares and 15 foals living on pasture with free access to water was recorded during 2,340 15-min focal samples taken over 2 yr. Lactating mares on pasture spent about 70% of the day feeding. Foals began feeding on their first day of life. As they grew older, they spent progressively more time feeding, but still spent only 47 +/- 6% of the time feeding by 21 wk of age. Foals fed primarily during the early morning and evening. While grass formed the major proportion of the diet of both foals and mares, they also ate clay, humus, feces, bark, leaves and twigs. Almost all feeding by foals was done while their mothers were feeding. Movement to water sources was frequently, but not invariably, carried out by an entire herd. Frequency (P = .005) but not duration (P greater than .05) of drinking bouts by mares increased as the temperature increased. Frequency was greatest at 30 to 35 C, at which temperature mares drank once every 1.8 h. Frequency of drinking varied with the time of day (P less than .01), being rarest during the early morning (0500 to 0900 h eastern daylight time) and most frequent during the afternoon (1300 to 1700 h). Drinking by foals was very rare. The youngest age at which a foal was observed to drink was 3 wk, and 8 of 15 foals were never observed to drink before weaning.

Abstract: The time-motion characteristics of Canadian basic- and medium-level dressage competitions are described, and the results are applied in formulating sport-specific conditioning programs. One competition was analyzed at the six levels from basic 1 to medium 3. Each test was divided into a series of sequences based on the type and speed of activity. The durations of the sequences were measured from videotapes. The basic-level tests had fewer sequences, and they were shorter in distance and duration than the medium tests (P < 0.10), but the average speed did not differ between the two levels. It is recommended that horses competing at the basic levels be conditioned using 5-min exercise periods, with short (10-s) bursts of lengthened trot and canter included at basic 2 and above. In preparation for medium-level competitions, the duration of the work periods increases to 7 min, 10- to 12-s bursts of medium or extended trot and canter are included, and transitions are performed frequently to simulate the energy expenditure in overcoming inertia.