Abstract: The canine teeth of the horse developed phylogenically from the simple, pointed, short-rooted tooth form of the leaf eating, in pairs living, Eocene horse Hyracotherium and served up to the Oligocene as a means of defense (self preservation). In the Miocene the living conditions of the Merychippus changed and they took to eating grass and adopted as a new behavior the life in a herd. The canine teeth possibly played an important role in fights for social ranking; they changed from a crown form to knife-like shape. In the Pliohippus the canine tooth usually remained in male horses and since the Pliocene, it contributed to the fights between stallions, to ensure that the offspring only came from the strongest animals (preservation of the species). Form and construction of the canine tooth are described and discussed in detail under the above mentioned phylogenic and ethologic aspects.

Abstract: Forty-one Dutch Warmblood immature horses were used in a study to quantify temperamental traits on the basis of heart rate (HR) and heart rate variability (HRV) measures. Half of the horses received additional training from the age of 5 months onwards; the other half did not. Horses were tested at 9, 10, 21 and 22 months of age in a novel object and a handling test. During the tests, mean HR and two heart variability indices, e.g. standard deviation of beat-to-beat intervals (SDRR) and root mean square of successive beat-to-beat differences (rMSSD), were calculated and expressed as response values to baseline measures. In both tests, horses showed at all ages a significant increase in mean HR and decrease in HRV measures, which suggests a marked shift of the balance of the autonomic nervous system towards a sympathetic dominance. In the novel object test, this shift was more pronounced in horses that had not been trained. Furthermore, statistical analysis showed that the increase in mean HR could not be entirely explained by the physical activity. The additional increase in HR, the nonmotor HR, was more pronounced in the untrained horses compared to the trained. Hence, it is suggested that this nonmotor HR might be due to the level of emotionality. HR variables showed consistency between years, as well as within the second year. These tests bring about a HR response in horses, part of which may indicate a higher level of emotionality; and horses show individual consistency of these HR variables over ages. Therefore, it is concluded that mean HR and HRV measures used with these tests quantify certain aspects of a horse's temperament.

Abstract: REASONS FOR PERFORMING STUDY: Behavioural tests as well as observers' ratings have been used to study horses' temperament. However, the relationship between the ratings and the responses in behavioural tests has not yet been studied in detail. OBJECTIVES: The aim of the present study was to examine this relationship between ratings and responses. METHODS: Eighteen mature Swedish Warmblood horses were subjected to 2 behavioural tests, one relating to novelty (novel object test) and one to handling (handling test). Subsequently, 16 of these horses were ridden by 16 equally experienced students, having no former experience with the horses. Immediately after each ride, the students scored the horse for 10 temperamental traits using a line rating method. RESULTS: It was shown that for each temperamental trait all 16 riders agreed on the ranking of the horses (0.212<W<0.505, P < 0.001). CONCLUSIONS: Correlations between behavioural and heart rate variables in the behavioural tests revealed that horses with a high level of locomotion or much restlessness behaviour exhibited high mean heart rate and low heart rate variability. In particular, heart rate variables in the behavioural tests were found to correlate with riders' rating scores. Furthermore, the underlying components of the handling test, retrieved with a principal component analysis (PCA) correlated with riders' rating scores while the underlying components of the novel object test did not. POTENTIAL CLINICAL RELEVANCE: It is concluded that it is possible for a large panel of assessors to agree upon a horse's temperament and that objective measures from behavioural tests correlate significantly with temperamental traits assessed by a panel of assessors.

Abstract: For a horse to succeed in a show-jumping career, the individual has to possess both excellent physical abilities as well as a suitable personality to perform under challenging conditions. Forty-one Dutch Warmblood horses were used to develop personality tests and correlations between test variables and early training performances in jumping were studied. In behavioural tests, during the first 2 years of the horses' lives, personality aspects like emotionality, reactivity to human and learning abilities were quantified. At the age of 3, horses were broken and received early training in show-jumping. The inter-relationship between several performance variables measured during this early training phase were studied using principal component analysis (PCA). Variables measured in the different personality tests (novel-object test, handling test, avoidance-learning test and a reward-learning test) showed no correlations, suggesting that these tests all triggered different aspects of a horse's personality. This study indicates that it is possible to predict a substantial part of the show-jumping performance of an individual horse later in life by personality traits earlier in life.

Abstract: The human-horse relationship forms an essential component in the diversity of todays use of horses. The reactions of horses to interactions with humans are mostly the result of interplay between their own temperament; the temperament and skills of the human and their previous experience – with humans. Moreover, the understanding of the human-horse relationship may improve the welfare of horses and humans. Nowadays, “sympathetic” training methods are gaining tremendous attention of horse owners. In the “sympathetic” training method the focus lies on the use of body language in human-horse communication, as well as respecting the horses natural needs. With 28 horses the effect of a “sympathetic” training method versus a conventional training method on the horse“s response on a human-approach test was studied. Fourteen horses of 3.5 years of age were subjected to a five week training period with a conventional training method, the other fourteen horses were subjected to a ”sympathetic“ training method. The overall frequency of snorting during the human approach tests decreased on average from 4.4 (± 1.1) before the training period to 3.1 (± 0.9) after the training period (both groups). However, there was a significant (p=0.006) difference between training methods: the horses trained in the ”sympathetic“ method decreased snorting by 4.3 (±1.1) while the horses trained in the conventional method increased with 1.5 (±0.9). While horses trained in the conventional method whinnied less in the second human approach test, horses trained in the ”sympathetic“ method whinnied more after the period of training. This difference was found to be significant (p=0.006). Defecating decreased over time, but was not different between training methods. The frequency of touching the unfamiliar handler increased over time for both training methods. The horses trained in a conventional method increased from 1.5 to 2.5 and for the sympathetic trained horses from 1.9 to 3.7. This increase was not significantly different for the training methods. Heart rate showed a minor decrease between the human approach tests (before training period 85.3 bpm, after training period 74.3 bpm) but there were no significant differences between training methods. Similarly, there was a slight increase in heart rate variability (rmssd: from 37.0 to 45.2), but no significant differences between training methods. Overal it was concluded that horses trained with this ”sympathetic“ method tended to be more trustful and less stressful in the presence of an (unfamiliar) human compared to horses trained with a conventional method. This may have been due to reduced stress during horse-human contact in the ”sympathetic" training method used. The long term effects on the welfare of the horses, still needs to be investigated.