Abstract: The ability of horses to habituate to frightening stimuli greatly increases safety in the horse-human relationship. A recent experiment suggested, however, that habituation to frightening visual stimuli is relatively stimulus-specific in horses and that shape and colour are important factors for object generalisation (Christensen et al., 2008). In a series of experiments, we aimed to further explore the ability of horses (n = 30, 1 and 2-year-old mares) to recognise and generalise between objects during habituation. TEST horses (n = 15) were habituated to a complex object, composed of five simple objects of varying shape and colour, whereas CONTROL horses (n = 15) were habituated to the test arena, but not to the complex object. In the first experiment, we investigated whether TEST horses subsequently reacted less to i) simple objects that were previously part of the complex object (i.e. testing for object recognition) and ii) a novel object (new shape and colour, i.e. testing for object generalisation), compared to CONTROLS. In the second experiment we investigated whether TEST horses reacted to a change in object order and object location. Behavioural reactions to the object, latency to eat, total eating time and heart rate were recorded. Compared to CONTROLS, TEST horses reacted significantly less towards objects, which were previously part of the complex object (e.g. mean heart rate; P = 0.006), indicating object recognition. In contrast to our expectations, TEST horses also reacted significantly less towards the novel object (e.g. mean heart rate; P = 0.018), suggesting that they were capable of object generalisation. We also found that TEST horses showed an increase in exploratory behaviour when objects within the complex object changed order and location (both P < 0.001), whereas there was no increase in heart rate, indicating that the horses were not frightened by the changes. The results demonstrate that it is possible to increase object generalisation in horses by habituating them to a range of colours and shapes simultaneously. This knowledge greatly affects the way in which horses may be trained to react calmly towards frightening objects.

Abstract: A 14-year-old Arabian cross-bred gelding was referred to the University Clinic because of mild, recurrent signs of colic for 5 days. The pony showed icteric mucous membranes, haemolytic blood, and dark coloured urine. Internal examination did not give a clear diagnosis. Unidentified intra-abdominal strands were found and haemorrhagic abdominocentesis led to the decision to perform an exploratory laparatomy. An extremely enlarged spleen was the sole finding. A splenal biopsy sample was taken and surgery was completed. The pony remained colicky, so the spleen was examined by ultrasonography. After this examination, the tentative diagnosis 'tumour of the spleen' was made and splenectomy was performed. Pathological examination of the spleen revealed splenomegaly caused by infarctions of unknown origin. Eight weeks after surgery, the pony started again in dressage competition. Six months after splenectomy, the pony won the provincial dressage competition.

Abstract: Unwanted oral investigative in horses has been anecdotally attributed to the practice of hand-feeding. Fears over such behaviour developing as a consequence of using food rewards, for example in clicker training, have been implicated as a common reason for not employing food-based positive reinforcement training techniques. This study used data generated as part of a larger research project, and explored associations between five common oral investigative behaviours and the practices of hand-feeding and clicker training. Data were from a convenience sample of UK leisure horse owners using two self-administered Internet surveys. Ninety-one percent of respondents reported giving their horse food by hand and this practice was significantly associated with three of the five oral investigative behaviours, licking hands (P = 0.006), gently searching clothing (P < 0.001) and roughly searching clothing (P = 0.003). Nipping hands and biting clothes were not associated with hand-feeding, suggesting that risk factors for these behaviours originate outside of this practice. Clicker training techniques were employed by 14% of respondents and their use was not associated with the incidence of any of the five oral investigative behaviours. These findings suggest that horse owners should not be deterred from using food-based positive reinforcement techniques with their horses, as fears that this practice will result in unwanted oral investigative behaviours from their horses appear unfounded.

Abstract: Behavioural observations suggest that smell is important in social discriminations between horses but balanced studies of this capacity are lacking. We used a habituation-discrimination procedure to investigate the ability of horses to distinguish between pairs of odour samples from different individuals. In Study 1, separate tests were conducted for urine, faeces or fleece fabric previously rubbed on the coat (to pick up body odour samples (BOS)) and donor pairs differed in sex, and age. 10 pregnant mares each underwent three tests, one per sample type. A test consisted of three successive 2-min presentations of a sample from Individual A with a simultaneous presentation of a sample from Individual B during the final presentation. Doubly repeated measures ANOVA indicated a main effect of sample type on investigative response (df = 2, f = 7.98, P = 0.004): durations were longer for BOS than for urine or faeces but habituation across trials was most consistent for urine. In the final presentation, mares demonstrated discrimination by investigating the novel urine sample (B) more than the repeated sample (novel: median 8.0 s, IQR = 10; repeated: median 2.5 s, IQR = 6; z = -2.558, P = 0.008). In Study 2, urine samples from castrated male donors were used and neither mares nor their 4-month-old foals discriminated between samples from different individuals in the final presentation. The findings suggest that urine odour may contain some information that horses can use to discriminate between conspecifics. This may be limited to the level of broad categories such as sex or reproductive status; further investigation is needed to reveal what functional information can be transmitted and what compounds are involved.

Abstract: Abstract Horses (Equus caballus) have a rich history in their relationship with humans. Across different cultures and eras they have been utilized for work, show, cultural rituals, consumption, therapy, and companionship and continue to serve in many of these roles today. As one of the most commonly trained domestic animals, understanding how horses learn and how their relationship with humans and other horses impacts their ability to learn has implications for horse welfare, training, husbandry and management. Given that unlike dogs and cats, domesticated horses have evolved from prey animals, the horse-human relationship poses interesting and unique scientific questions of theoretical value. There is still much to be learned about the cognition and behaviour of horses from a scientific perspective. This review explores current research within three related areas of horse cognition: human-horse interactions, social learning and independent learning in horses. Research on these topics is summarized and suggestions for future research are provided.