Abstract: A traumatic fracture of C2 was diagnosed radiographically in a 1-year-old German Warm-blood stallion. Fracture configuration was difficult to see on survey radiographs. Computed tomography yielded a more accurate assessment of the fracture and facilitated fracture repair with cortical lag screws. Precise screw placement, to avoid spinal cord damage, was obtained by use of computed tomography. Follow-up radiography revealed normal bone healing, and the horse was in dressage schooling 24 months after surgery.

Abstract: Recent experimental evidence indicates that females may copy the mate choice of others. Here, we present a model for the evolution of mate copying strategies in lekking species. In the model, all females (copiers and non-copiers) assess male quality, but a copier's assessment of a male's quality increases after males have mated with other females. The model demonstrates that mate copying is favored when breeding late in the season has a relatively high cost. We hope that our results will spur empirical work quantifying the time constraints associated with breeding, thus allowing more direct tests of the model's predictions.

Abstract: In this study genetic parameters of linear scored conformation traits of the Dutch Warmblood Riding Horse were estimated in relation to performance in competition. Observations on 10 665 mares were analyzed with an animal model including the fixed effects age, classifier, location and percentage of thoroughbred. Using restricted maximum likelihood algorithms, heritabilities of 26 linear scored conformation traits were estimated in the range 0.09-0.28. Several conformation traits had high up to very high mutual genetic correlations. Competition results of 3476 horses with performance in dressage and 3220 horses with performance in show-jumping were linked to the conformation data to estimate the genetic relationship between conformation and performance in competition. The model for the evaluation of the competition results included the fixed effects riding club, age and sex. Estimated heritabilities for dressage and show-jumping were 0.17 +/- 0.05 and 0.19 +/- 0.04, respectively. Genetic correlations between conformation and performance were low to moderate. The length of the neck, length and position of the shoulders, shape and length of croup and muscularity of the haunches had a significant moderate genetic correlation with dressage. Muscularity of the neck, shape of the croup and muscularity of the haunches had a significant genetic correlation with show-jumping. The results indicate that, due to the low genetic correlations with performance traits, indirect selection for performance using conformation results is of limited value.

Abstract: Psychometric findings are reported from two studies concerning the construct validity, temporal stability, and interrater reliability of the latent common factors underlying subjective assessments by human raters of personality traits in two nonhuman animal species: (a) the Stumptail macaque (Maraca arctoides), a cercopithecine monkey; and (b) the Zebra finch (Poephila guttata), an estrildid songbird. Because most theories of animal personality have historically implied that certain personality constructs should be relatively universal across taxa, parallel analyses of similar data are reported for two phylogenetically distant species of subject using the same psychometric methods. Each of the samples was drawn from a socially-housed colony of the same species: that of macaques consisted of 5 mature adult fem ales and 8 of their adult offspring and that of finches consisted of 5 adult individuals. A modified version of the 1978 Stevenson-Hinde and Zunz (SHZ) list of personality items was applied to the macaques at various times during the eight years from 1980-1988 and to the finches during 1992. This study also used the three SHZ scales – Confident, Excitable, and Sociable – originally derived from principal components. Generalizability analyses were used to assess the construct validity, temporal stability, and interrater reliability of the hypothesized factors. Both Stumptail macaques and Zebra finches manifest measurable personality factors that are highly valid across multiple items, stable across multiple years, and reliable across multiple raters. The same model fits both species, as predicted by theory. The construct validity of the factors is slightly higher for the finches than for the macaques, although the interrater reliability is somewhat lower. This study illustrates how generalizability analysis can be used to test prespecified confirmatory factor models when the number of individual subjects is quite small.

Abstract: Feral horses are social animals, which have to rely on survival strategies centered on the formation of cohesive social bonds within their bands. Many problems in the husbandry of social animals such as horses, are due to the fact that the limits of their adaptive abilities are exceeded. Evidence suggests that the fundamental social characteristics of domestic horses have remained relatively unchanged. The social structure, social strategies and social interactions were investigated (3 non-consecutive years, 24 hr per day for several weeks) in long term established groups of domestic horses (mares and geldings of all ages) and a few small introduced groups, kept in (semi)natural environments. The general aim was to investigate the social needs of domestic horses. The social life of domestic horses was characterised by long lasting bonds with preferred partners which were established and maintained by allogrooming, play, proximity and dominance behaviours. Bonding partners were mainly found within the same sex-age group, but adult geldings also bonded with sub-adult mares and geldings. Adult mares were clustered in a group, while the other animals formed a second group. Among the adult mares, subgroups according to reproductive state were formed. Individuals regulated their social network by interfering with interactions between other members of the herd, which in itself is complex. An intervention is a behavioural action of one animal that actively interferes with an ongoing interaction between a dyad with the apparent aim of altering that interaction. This was verified by post-hoc analyses of disturbed and undisturbed interactions. Interventions in allogrooming or play were performed significantly more often when at least one member of the initial dyad was a preferred partner of, or familiar to (within the small introduced bands) the intervener. The stronger the preferred association in allogrooming between the intervener and member(s) of the initial dyad, the higher the probability the intervener would displace one initial member and continue allogrooming with the other. Just five behaviours were extracted which reliably reflected the dominance relations among horses. Aggression with the hind quarters was used both offensively and defensively and therefore not suitable as a reliable parameter. Individual dominance relationships were related to social experience. The implications of these findings for horse husbandry were assessed. It is argued that the execution of affiliative behaviours may be rewarding in itself, and therefore always will be a highly motivated behaviour. It is shown that social positive physical interactions (allogrooming, play) with other horses is an ethological need and therefore indispensable in modern husbandry systems. Ethological needs are so important for the animal that husbandry systems that lack the possibilities to execute such behaviours will cause chronic stress. It is concluded that all horses need physical social contact, and that horses, which lack appropriate social learning experiences during ontogeny, may be hampered in their social functioning later in life. Solutions for problems, including dominance problems, in individual social housing and group housing are presented.