Abstract: This study investigated the effect of stimulus height on the ability of horses to learn a simple visual discrimination task. Eight horses were trained to perform a two-choice, black/white discrimination with stimuli presented at one of two heights: ground level or at a height of 70 cm from the ground. The height at which the stimuli were presented was alternated from one session to the next. All trials within a single session were presented at the same height. The criterion for learning was four consecutive sessions of 70% correct responses. Performance was found to be better when stimuli were presented at ground level with respect to the number of trials taken to reach the criterion (P < 0.05), percentage of correct first choices (P < 0.01), and repeated errors made (P < 0.01). Thus, training horses to carry out tasks of visual discrimination could be enhanced by placing the stimuli on the ground. In addition, the results of the present study suggest that the visual appearance of ground surfaces is an important factor in both horse management and training.

Abstract: OBJECTIVE: To describe spontaneous locomotion activity of foals kept under various management conditions and assess the suitability of global positioning system (GPS) technology for recording foal activity. Animals-59 foals. PROCEDURES: During the foals' first 4 months of life, 921 observation periods (15 minutes each) were collected and analyzed for locomotion activities. The GPS system was evaluated by simultaneously carrying out field observations with a handheld computer. RESULTS: Foals spent 0.5% of total observed time cantering, 0.2% trotting, 10.7% walking, 32.0% grazing, 34.8% standing, and 21.6% lying down. Total observed daytime workload (velocity x distance) in the first month was approximately twice that in the following months. Locomotion activity decreased with increasing age. Colts had more activity than fillies in certain periods, and foals that were stabled for some portion of the day had compensatory locomotion activity, which was probably insufficient to reach the level of foals kept continually outside. The GPS recordings and handheld-computer observations were strongly correlated for canter, trot, and walk and moderately correlated for standing and lying. Correlation for grazing was low. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that domestically managed foals, when kept 24 h/d at pasture, will exercise at a level comparable with feral foals. High workload during the first month of life might be important for conditioning the musculoskeletal system. The GPS technique accurately quantified canter, trot, and walk activities; less accurately indexed resting; and was unsuitable for grazing because of the wide array of velocities used while foraging.

Abstract: The restricted access to pasture experienced by many competition horses has been linked to the exhibition of stereotypic and redirected behaviour patterns. It has been suggested that racehorses provided with more than one source of forage are less likely to perform these patterns; however, the reasons for this are currently unclear. To investigate this in 4 replicated trials, up to 12 horses were introduced into each of 2 identical stables containing a single forage, or 6 forages for 5 min. To detect novelty effects, in the first and third trials the single forage was hay. In the second and fourth, it was the preferred forage from the preceding trial. Trials were videotaped and 12 mutually exclusive behaviour patterns compared. When hay was presented as the single forage (Trials 1 and 3), all recorded behaviour patterns were significantly different between stables; e.g. during Trial 3 in the 'Single' stable, horses looked over the stable door more frequently (P<0.001), moved for longer (P<0.001), foraged on straw bedding longer (P<0.001), and exhibited behaviour indicative of motivation to search for alternative resources (P<0.001) more frequently. When a previously preferred forage was presented as the single forage (Trials 2 and 4) behaviour was also significantly different between stables, e.g in Trial 4 horses looked out over the stable door more frequently (P<0.005) and foraged for longer in their straw bedding (P<0.005). Further study is required to determine whether these effects persist over longer periods. However, these trials indicate that enrichment of the stable environment through provision of multiple forages may have welfare benefits for horses, in reducing straw consumption and facilitating the expression of highly motivated foraging behaviour.

Abstract: Samples of seven of the 10 morphological species of midges of the Culicoides imicola complex were considered. The importance of this species complex is connected to its vectorial capacity for African horse sickness virus (AHSV) and bluetongue virus (BTV). Consequently, the risk of transmission may vary dramatically, depending upon the particular cryptic species present in a given area. The species complex is confined to the Old World and our samples were collected in Southern Africa, Madagascar and the Ivory Coast. Genomic DNA of 350 randomly sampled individual midges from 19 populations was amplified using four 20-mer primers by the random amplified polymorphic DNA (RAPD) technique. One hundred and ninety-six interpretable polymorphic bands were obtained. Species-specific RAPD profiles were defined and for five species diagnostic RAPD fragments were identified. A high degree of polymorphism was detected in the species complex, most of which was observed within populations (from 64 to 76%). Principal coordinate analysis (PCO) and cluster analysis provided an estimate of the degree of variation between and within populations and species. There was substantial concordance between the taxonomies derived from morphological and molecular data. The amount and the different distributions of genetic (RAPD) variation among the taxa can be associated to their life histories, i.e. the abundance and distribution of the larval breeding sites and their seasonality.

Abstract: Reliable physiological markers for performance evaluation in sport horses are missing. To determine the diagnostic value of plasma ACTH and cortisol measurements in the warmblood horse, 10 initially 3-yr-old geldings of the Hannovarian breed were either exposed to a training schedule or served as controls. During experimental Phase 1, horses were group-housed, and half of the horses were trained for 20 wk on a high-speed treadmill. During Phase 2, groups were switched and one group was trained for 10 wk as during Phase 1, whereas the control group was confined to boxes. During Phase 3 horses were initially schooled for riding. Thereafter, all horses were regularly schooled for dressage and jumping, and half of the horses received an additional endurance training for 24 wk. During all phases horses were exposed at regular intervals to various standardized treadmill exercise tests. During and after the tests frequent blood samples were taken from an indwelling jugular catheter for determination of ACTH and cortisol. Treadmill exercise increased both hormones. Maximum ACTH concentrations were recorded at the end of exercise, and maximum cortisol levels were recorded 20 to 30 min later. Except for one test there were no differences in ACTH levels between trained horses and controls. There was no significant effect of training on the cortisol response (net increase) to treadmill exercise in any of the tests during Phase 1. During Phase 2 higher cortisol responses were recorded in controls than in trained horses (P < .05) after 10 wk of training (controls confined to boxes). During Phase 3 plasma cortisol responses were also higher in controls than in trained horses (P < .05 after 6, 18, and 24, P < or = .07 after 12 wk of training) when the inclination of the treadmill was 5%, but not at 3%. There was no overlap in net cortisol responses at 30 min between trained and untrained horses. An ACTH application after 24 wk of training resulted in higher cortisol responses in controls than in trained horses (P < or = .05), without any overlap between the groups at 30 min after ACTH. Plasma cortisol responses to either treadmill exercise or ACTH injection may be a reliable physiological marker for performance evaluation. Prerequisites are sufficient differences in training status and sufficient intensity of exercise test conditions.