Abstract: As previously reported (Beran and Rumbaugh, 2001), two chimpanzees used a joystick to collect dots, one-at-a-time, on a computer monitor, and then ended a trial when the number of dots collected was equal to the Arabic numeral presented for the trial. Here, the chimpanzees were presented with the task again after an interval of 6 months and then again after an additional interval of 3.25 years. During each interval, the chimpanzees were not presented with the task, and this allowed an assessment of the extent to which both animals retained the values of each Arabic numeral. Despite lower performance at each retention interval compared to the original study, both chimpanzees performed above chance levels in collecting a quantity of dots equal to the target numeral, one chimpanzee for the numerals 1-7, and the second chimpanzee for the numerals 1-6. For the 3.25-year retention, errors were more dispersed around each target numeral than in the original study, but the chimpanzees' performances again appeared to be based on a continuous representation of magnitude rather than a discrete representation of number. These data provide an experimental demonstration of long-term retention of the differential values of Arabic numerals by chimpanzees.

Abstract: Subjects in conditioning experiments time their conditioned responses relative to the onsets of the conditioned stimuli (CSs). These onsets are temporal landmarks, by reference to which subjects may estimate the location of the unconditioned stimulus (US) in time. In a serial compound conditioning paradigm, a long duration CS comes on first, followed later by a second shorter CS, creating both a long-range and a short-range predictor of the US. We ask whether displacing the short-range predictor relative to the long-range predictor causes subjects to strike a compromise between the different temporal locations predicted by the two CSs. In three experiments with pigeons, we varied the training conditions so as to favor or militate against this outcome. However, in all conditions, there was no compromise; after the onset of the displaced short-range CS, the timing of conditioned responding was governed by it alone. This result contrasts with the compromises that are seen when the feeding time predicted by a CS is put in conflict with the time predicted by the circadian clock, and with the similar compromises sometimes seen when a nearby spatial landmark is displaced relative to a larger spatial context.

Abstract: REASONS FOR PERFORMING STUDY: There is limited knowledge available of factors influencing response to treatments of the DIP-joint in horses with lameness responding to diagnostic analgesia of the DIP-joint. For this reason a multivariable statistical analysis was performed. HYPOTHESIS: Horses with lameness reduced by > or = 75% 10 min after intra-articular analgesia of the DIP-joint, can be treated successfully by intra-articular medication of the joint. Multiple factors influence the response to treatment. METHODS: The study was performed retrospectively based on clinical records of horses treated with either polysulphated glycosaminoglycan (PSGAG) or methylprednisolone acetate (MPA) in the DIP-joint between January 1996 and January 2003. Information was collected from clinical records and from the owners of the horses via a detailed questionnaire, in which they described their perception of the outcome a minimum of one year after treatment. Allocation of the horses to the 2 treatment groups was done mainly because of a change in treatment policy. In Regime A all horses received 3 intra-articular injections of PSGAG approximately 8 days apart, whereas in Regime B all horses received a single intra-articular injection of MPA as a first treatment. If the horse did not improve sufficiently to return to work by 4 weeks, a series of 3 intra-articular PSGAG injections was administered. RESULTS: Of the horses receiving Regime A, 67% had a successful outcome, compared with 46% of the group receiving Regime B. A significantly better result was obtained in dressage horses than in jumping horses (eventing and showjumping). Other variables such as age, duration of lameness, distribution of lameness, degree of lameness, response to DIP-joint analgesia and radiographic observations were also associated with success of treatment. CONCLUSIONS AND POTENTIAL RELEVANCE: There is a rationale for using either PSGAG or MPA intra-articularly in the treatment of lameness, reduced > or = 75% within 10 min of analgesia of the DIP-joint.

Abstract: Weaning foals marks a stressful event in horses' lives. Limited research exists regarding different housing methods post-weaning and the long-term implications on horse behavior and welfare. The purpose of this study was to monitor behavior and physiological stress markers in horses weaned individually in solid partition box stalls versus horses weaned in small groups and housed in paddocks. Both treatment groups underwent maternal deprivation stress, but the stalled weanlings had the additive effects of social isolation which prevented them from performing social behaviors. Quarter Horse weanlings from the Michigan State University, Merillat Equine Center, average age 4.5 months, were weaned in 13.4 m2 box stalls (n=6) or in groups of three in a 992 m2 paddock, which had very limited grazing forage and an open shelter available (n=6). Subjects were fed concentrate and hay to National Research Council recommendations. A time budget for 31 observed behaviors was developed. Behavioral observations were made 2 days per week, approximately 6 h per day, for the duration of the 56 days study. Instantaneous samples were recorded every 5 min on each observation day, with equal division between the two treatment groups (n=35 scans per horse per observation day). Focal data were recorded continuously between scans to provide a more detailed ethogram. On each observation day, fecal samples were collected to measure 11,17-dioxoandrostanes, an indicator of glucocorticoid metabolite concentration. Regarding the fecal 11,17-dioxoandrostanes, there was no discernible treatment difference either immediately post-weaning or at the conclusion of the 56 days study. Interestingly, all 12 weanlings showed a 4 week post-weaning increase in 11,17-dioxoandrostanes. The reason for this peak was unclear. Behavioral observations demonstrated a significantly different time budget in paddock-housed weanlings than in stall-housed weanlings (P<0.0001). Paddock-housed weanlings displayed a time budget more like a feral horse time budget, showing more time spent moving and less time spent lying. Paddock-housed weanlings, who had the option of selectively engaging in a broader range of behaviors, showed strong motivation to graze and be near conspecifics. Stalled weanlings spent significantly more time engaged in aberrant behaviors: licking or chewing the stall/shed wall, kicking at the stall/shed wall, pawing, and bucking/rearing bouts (P<0.03). Based on the variety of behaviors shown, the ability to engage in strongly preferred behaviors, and freedom from aberrant behavior, we conclude that the paddock-reared, group-housed weanlings had better welfare. However, there was insufficient evidence to conclude that the stalled weanlings had poor welfare.