Abstract: The biological diversity of a species gives rise to individual differences in behavioural tendency. Traditionally, this variation has been considered to be of little scientific importance or value, but the description and quantification of the fundamental basis of this variability is relevant to many aspects of equine science. The reliable identification of these features may allow the development of more accurate diagnostic and prognostic indicators for a range of clinical diseases. Biologically based traits also provide a more rational basis for selective management and breeding programmes in which specific behavioural tendencies are sought. Individual differences in behaviour also reflect the range of subjective feelings experienced by animals and therefore need to be understood by those concerned with animal welfare. Psychometric techniques concerned with the assessment of personality may provide a suitable basis for scientific study in this field. Potentially methodologies include: behavioural tests, objective behaviour measures or the quantification of reports from those familiar with the subjects. The assessment of the validity and reliability of the variables measured in these tests is an integral part of their development. Interobserver correlation in an experiment based on the subjective rating of 20 horses with respect to 14 familiar terms used to describe horse personality was generally low. This suggests that, with the exception of the terms 'flighty' and 'sharp', the empirical terminology commonly used to describe horse personality is unreliable.

Abstract: Crib-biting is a common oral stereotype. Because of perceived deleterious effects on the health and appearance of subjects the prevention of crib-biting is regularly attempted. The resourcefulness of horses in satisfying their motivation to perform this behaviour often frustrates owners' efforts at prevention. This paper reviews the efficacy and observable consequences of attempting to prevent crib-biting by a variety of methods. These include attempts to prevent the grasping of objects, to interfere with air-engulfing and to introduce punishment for grasping and neck-flexion. Other approaches include the use of surgery, acupuncture, pharmaceuticals, operant feeding and environmental enrichment. A remedy that is effective for every crib-biter remains elusive. We conclude that, rather than concentrating on remedial prevention, further research should be directed at establishing why horses crib-bite and how the emergence of crib-biting can be avoided.

Abstract: Horses constantly modify their behaviour as a result of experience. This involves the creation of an association between events or stimuli. The influence of people on the modification and generation of certain behaviour patterns extends beyond the intentional training of the horse. The impact of any action depends on how it is perceived by the horse, rather than the motive of the handler. Negative and positive reinforcement increase the probability of specific behaviours recurring i.e. strengthen the association between events, whereas punishment reduces the probable recurrence of a behaviour without providing specific information about the desired alternative. In this paper the term 'punishers' is used to refer to the physical aids, such as a whip or crop, which may be used to bring about the process of punishment. However, if their application ceases when a specific behaviour occurs they may negatively reinforce that action. Intended 'punishers' may also be rewarding (e.g. for attention seeking behaviour). Therefore, contingency factors (which define the relationship between stimuli, such as the level of reinforcement), contiguity factors (which describe the proximity of events in space or time) and choice of reinforcing stimuli are critical in determining the rate of learning. The many problems associated with the application of punishment in practice lead to confusion by both horse and handler and, possibly, abuse of the former. Most behaviour problems relate to handling and management of the horse and can be avoided or treated with a proper analysis of the factors influencing the behaviour.

Abstract: To elucidate the molecular mechanisms of red-green color vision in mammals, we have cloned and sequenced the red and green opsin cDNAs of cat (Felis catus), horse (Equus caballus), gray squirrel (Sciurus carolinensis), white-tailed deer (Odocoileus virginianus), and guinea pig (Cavia porcellus). These opsins were expressed in COS1 cells and reconstituted with 11-cis-retinal. The purified visual pigments of the cat, horse, squirrel, deer, and guinea pig have lambdamax values at 553, 545, 532, 531, and 516 nm, respectively, which are precise to within +/-1 nm. We also regenerated the “true” red pigment of goldfish (Carassius auratus), which has a lambdamax value at 559 +/- 4 nm. Multiple linear regression analyses show that S180A, H197Y, Y277F, T285A, and A308S shift the lambdamax values of the red and green pigments in mammals toward blue by 7, 28, 7, 15, and 16 nm, respectively, and the reverse amino acid changes toward red by the same extents. The additive effects of these amino acid changes fully explain the red-green color vision in a wide range of mammalian species, goldfish, American chameleon (Anolis carolinensis), and pigeon (Columba livia).