Equine coital exanthema (ECE), caused by equid herpesvirus 3 (EHV-3), is a contagious venereal disease characterised by the formation of painful papules, vesicles, pustules and ulcers on the external genitalia of both mares and stallions. EHV-3 is an alphaherpesvirus, distinct from the other equine herpesviruses, endemic in most horse breeding populations worldwide. EHV-3 is primarily transmitted through coitus, although there is also evidence supporting the possibility of non-coital spreading through infected fomites and contacts other than coitus. The infection does not usually result in systemic illness. Epidemiological observations and serological monitoring suggest the existence of latently infected animals from which EHV-3 is periodically reactivated and transmitted to cohorts but latency of EHV-3 has not been formerly demonstrated. The negative impacts of ECE on equine breeding enterprises are the forced, temporary disruption of the mating activities of mares and stallions, the additional care and supportive treatment in affected horses, and the risk of virus spread by either fresh or frozen semen as well as by artificial insemination and embryo transfer practices. In intensively managed stud operations, which have heavily-scheduled breeding dates for thoroughbred stallions, breeding disruptions may translate into significant end-of-season decreases in the number of entries into the mare book of affected stallions. Also, delayed foaling dates and/or reduced pregnancy rates may occur in mares that miss breeding opportunities due to the disease. Similarly, in the face of an ECE outbreak in artificial insemination and embryo transfer centres, both donor and recipient affected mares show such discomfort that they are reluctant to be inspected, inseminated or transferred, with the consequent loss of opportunity to become pregnant. The additional time and necessary precautions required to manage the donor and receptor mares due to the presence of the disease also have a substantial negative impact. Because ECE is a not a notifiable disease and the diagnosis is made on the basis of typical clinical signs, most cases and outbreaks of ECE remain unnoticed and its true prevalence and economic impact is difficult to assess and is probably underestimated. Therefore, as several aspects of EHV-3 infection are largely unknown and it has severe economic consequences to the horse industry, the general aim of this doctoral study was to increase the knowledge about the biology of EHV-3 infection. The specific objectives were to investigate the iatrogenic transmission of infection and to set up a protocol for experimental reproduction of the disease, to study the reactivation and re-excretion patterns from latency, to evaluate the epidemiological importance of subclinical infections, and to hypothesise about the ECE economic consequences in the current context of the equine industry. During the occurrence of an outbreak of ECE in an embryo transfer centre, approximately 32% (n=35) of the donor mares and 25% (n=125) of the recipient mares showed typical ECE lesions around the anus and on the perineal skin, discomfort, and anorectal lymphadenopathy. EHV-3 was detected in 7 (58%) of the affected mares and specific antibodies in 23 (88%) of the convalescent mares. Since no natural breeding had taken place on the affected mares, it could be hypothesised that the virus spread was a consequence of contamination by means of the gloves or the ultrasonography scanner used. Lymphadenopathy provides a new concern associated with ECE. EHV-3 was isolated from nasal swabs obtained during an outbreak of unilateral rhinitis affecting approximately 40 out of 2000 thoroughbred horses. The fact that an endoscopic examination had been performed in the week previous to the onset of the lesions to evaluate the respiratory tract function was a common finding in all the horses affected. EHV-3 was demonstrated as the etiologic agent of the unilateral rhinitis observed in those 40 thoroughbred horses. The endoscope used for respiratory tract examination was identified as the most likely cause of the spread of the infection. This case is an example of non-genital iatrogenic transmission and reinforces the importance of strict application of hygienic measures in order to reduce the risk of spread of infectious diseases. The virus isolated from this field outbreak as well as that isolated from others were characterized by means of restriction endonuclease (RE) fragment patterns, plaque size and gG gene partial nucleotide sequencing. In the 25 isolates included in the study, different RE patterns were found: two with BamHI (one of them identical to the one of the reference strain), two with Hind III (both different from the one of the reference strain) and one with Eco RI (different from the one of the reference strain). The plaque size was homogeneous between the isolates, and 1.64 and 2.88 times larger than that of the reference strain. Three base substitutions in the gG gene were found at positions 904, 1103 and 1264, which resulted in strains CAT (Australia), AAT (the United States and Brazil), CAG (Argentina) and ACT (Argentina). The RE pattern and the nucleotide sequence of the gG gene obtained revealed that there are genetically distinguishable EHV-3 strains in circulation. Not only the RE patterns, as previously described, but also the nucleotide sequence of the gG gene, could be useful tools for epidemiological studies. The biological implications of these changes are still unknown. Two sets of experimental infection with EHV-3 were carried out under controlled conditions. In the first experiment, two seronegative mares were topically inoculated in the vagina and perineal area with EHV-3. The same protocol was followed in the second experiment in two seronegative and two seropositive mares (the mares which had been included in the first experiment were used six months later). Clinical samples consisted of swabs from the vagina and perineal area, and blood samples were obtained for virological, serological and haematological studies. A scoring system was designed and used for daily clinical evaluation and rectal temperature records from each mare. Neither hyperthermia nor haematological changes were recorded in the mares analyzed. Typical ECE lesions were observed in seronegative animals: the clinical score was 172 and 90 (average score: 131) for the mares included in the first experiment and 160 and 92 (average score: 124) for the mares included in the second experiment. Only slight lesions were observed in the seropositive mares, being the clinical score 53 and 41 (average score: 47). Also, differences were detected in the duration and intensity of virus shedding, being 15 and 9 days (duration) and 105 versus 104 (the highest virus load detected) in the seropositive and seronegative mares, respectively. In one study designed to demonstrate EHV-3 latency and to study reactivation and re-excretion patterns, virus shedding, seroconversion and the presence of a small ECE lesion were observed in one out of two previously naturally infected mares after corticosteroid treatment. EHV-3 was isolated from perineal vaginal swabs of one of the mares, both on day 14 after corticosteroid treatment and along the following 10 days. A small and rounded area of erosion was observed on the left labia of the vulva of the same mare on day 19 after corticosteroid treatment and 5 days after the virus shedding was detected. A significant (four-fold) increase in the antibody titre was found in the mare which shed the virus 28 days after corticosteroid treatment and 14 days after the beginning of virus re-excretion. In concordance with epidemiological observation and serological studies, and in common with other members of the subfamily Alphaherpesvirinae, this study indicates that a state of latency is established after natural infection of EHV-3. A study was carried out to estimate the prevalence of excretion of EHV-3 under field conditions. The virus was detected in perineal-vaginal swabs by real time PCR and specific antibodies were identified by seroneutralization in 14 (6%) and 105 (48%) respectively of 220 thoroughbred mares without clinical signs at the time of breeding. In order to assess the re-excretion patterns of spontaneous reactivation, two seropositive (presumably latently infected) polo mares were kept in isolation for 11 months. Virological investigations on perineal vaginal swabs obtained on a daily basis revealed re-excretion of EHV-3 on two occasions, 3 months apart (each for a 3-day interval) in one of the mares, and on only 1 day in the other mare. Antibodies against EHV-3 were detected with only slight variation during the entire period in both mares. Clear evidence of the existence of EHV-3 shedders in a healthy mare population under both field and isolation conditions is provided. Furthermore, despite the small number of animals included (only two), the study in mares kept in isolation demonstrated that at least two periods of EHV-3 spontaneous reactivation and re-excretion in the presence of serum antibodies were possible in the same animal in an 11-month interval. In conclusion, EHV-3 infections and ECE are still a threat for the equine industry. In the present study, EHV-3 was found in several field outbreaks of ECE in thoroughbred breeding farms; the disease was reported by the veterinarians as a true sanitary problem and thus demands additional preventive measures. In addition, EHV-3 was detected as a not rare event in clinically healthy mares, which constitutes the most relevant finding from an epidemiological perspective. ECE is also a sanitary problem of concern for embryo transfer and routine veterinary practices. The population of EHV-3 latently infected mares which reach up to 50% at the time of breeding deserves special attention. Reactivation of the latent virus is not preventable and those mares can spontaneously reactivate the virus and become a source of infection for highly valuable horses like « shuttle stallions », with the consequent economically negative impact on the equine enterprises. Finally, there is an important need for finding out additional preventive measures including « pen side » diagnostic tools that allow the detection of subclinically EHV-3 shedding mares in order to segregate them from natural breeding and give them an appropriate antiviral treatment before being covered by stallions.

Thèse de doctorat : Physiologie et biologie des organismes, populations, interactions : Strasbourg 1 : 2007. / Texte en français et en anglais. Titre provenant de l'écran-titre. Bibliogr. p. 219-239.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Depuis sa domestication, le cheval revêt différents enjeux économiques, sociaux, politiques, et même religieux inhérents au fonctionnement de nombreuses cultures. C’est pourquoi il est devenu un sujet d’étude à part entière. Pour autant, la question de l’élevage a été peu traitée par les historiens. Or, ne pas s’interroger sur l’élevage et sur les motivations des éleveurs revient à oublier le point de départ de toute histoire abordant les divers usages du cheval. L’élevage, c’est veiller à la fois à la reproduction, à la naissance, au développement et à l’entretien d’un animal. Pour le nourrir, le sélectionner, le soigner, l’exploiter, il faut beaucoup de temps, de soins, de connaissances, de patience, beaucoup d’hommes bien sûr et des structures adaptées : les haras. C’est pourquoi, cette activité était réservée à l’élite et s’inscrivait au sein d’une certaine idéologie aristocratique : le cheval de l’Antiquité était un cheval de prestige. Grâce aux sources littéraires, iconographiques et archéologiques, nous étudierons les permanences et les mutations qu’a connu l’élevage pendant une période charnière (entre la fin de l’Empire romain d’Occident et la création des royaumes romano-germaniques). Ainsi, nous entendons mesurer les impacts des invasions et de l’assimilation des peuples barbares dans l’Empire sur l’élevage des chevaux et comment et pourquoi, malgré des bouleversements, politiques, sociaux et économiques, cette activité est restée prospère. Ceci permettra de comprendre qui élevait des chevaux, quels facteurs poussaient à l’organisation d’un cheptel chevalin, dans quels types de structures cela était organisé, quels méthodes et savoirs étaient requis et comment le cheval devint un élément de référence pour classer un homme au sein de la société. / Since its taming, the horse took on different economical, social and political issues, and even religious ones inherent to the functioning of many cultures. That’s why it became a study matter in its own right. However, the topic of its farming has been very little dealt with by historians. But, not questionning its farming and the farmers’ motivations would be forgetting the starting point of any story tackling the varied uses of horses. Farming, is making sure of the reproduction, the birth, the development and the upkeep of an animal. To feed it, choose it, care for it, farm it, a lot of time is required, care, knowledge, patience, a large staff of course and fitting structures : stud farms. That’s why this activity was reserved to the elite and encountered inside a particular upper-class ideology : a horse in the Antiquity was an animal of prestige. Thanks to literary, iconographic and archeological sources, we will study the permanencies and changes that farming has known during a transition period ( between the end of the Wester Roman Empire and the creation the Romano – Germanic Kingdoms ). Thus, we will intend to determine the different impacts that invasions have had and the assimilation of the savages in the Empire on horse farming and how and why, despite political, social and economical disruptions, this activity stayed flourishing. It will allow to understand who farmed the horses, what factors drove to the organisation of horse stocking, in what kind of structures it was organised in, what method and knowledge were needed and how a horse became a ranking aspect for a man in society.

La littérature équine comprend peu d’études relatives aux coordinations cavalier-cheval. Ces dernières n’ont été examinées qu’en situations expérimentales sur des durées courtes. Le récent développement des technologies embarquées ouvre de nouvelles perspectives en permettant l’enregistrement combiné des déplacements du cavalier et du cheval durant plusieurs heures. Ce travail de thèse vise, au travers de l'identification de variables macroscopiques, à définir les caractéristiques du couplage cavalier-cheval (CCC) en situation naturelle de course d’endurance. Utilisant les concepts et outils de l’approche des systèmes dynamiques, nos résultats valident une méthodologie permettant d'identifier sur la seule base du CCC les allures et techniques de monte utilisées en compétition d’endurance. Les caractéristiques quantitatives et qualitatives du CCC évoluent différemment tout au long de la course en fonction du niveau d’expertise du couple. Les couples élites présentent une augmentation de vitesse et du pourcentage de petit galop assis alors que les couples expérimentés conservent la même répartition des quatre allures/techniques et les mêmes vitesses. La détérioration de la qualité du couplage observée chez les deux groupes pourrait être attribuée à la fatigue pour les expérimentés alors qu’elle pourrait provenir en partie de l’élévation de la vitesse chez les élites. Cette méthode d’analyse du couplage a fourni les premières observations sur l’influence d’un style de monte émergent sur la performance d’endurance. Nos perspectives visent à développer un dispositif selle-sangle instrumenté permettant l'optimisation du CCC en situation d'entraînement et de compétition. / Equine literature includes only a very limited number of studies related to horse-rider coordination. In addition, these were only investigated in experimental situations limited to a few minutes and during prescribed horse gait and riding techniques. The recent development of mobile technologies offers new perspectives allowing several hours of synchronized horse and rider recordings. This PhD work aims, through some remarkable macroscopic variables, to characterize the horse-rider coupling (HRC) in the various contextual situations of endurance races. Using concepts and tools of self-organizing dynamic system approach, a method was developed and validated to identify, on the sole basis of HRC, horse’s gaits and riding techniques used in endurance competition. This method revealed the emergence of four HRC patterns along endurance race. Quantitative and qualitative characteristics of the HRC were found to evolve differently throughout the race depending on the expertise level of the dyad. Elite dyads present increases in speed and percentage of sitting canter while advanced dyads maintain the same distribution and averaged speeds for the four horse’s gaits/riding techniques. The reduced quality of the coupling demonstrated by both groups at the end of race may be attributed to fatigue for the advanced dyads while it might also result from the increase in speed for the elite dyads. This method developed for the HRC analysis allowed us to study the influence of an emerging riding style on the endurance performance. Our perspectives in the equestrian domain intend to develop an instrumented saddle-girth device to optimize HRC in both training and competitive situations.

Le premier objectif de ce travail de thèse était de développer la méthodologie d’étude des postures basée sur la morphométrie géométrique. Cela nécessitait un perfectionnement de la méthodologie déjà existante sur la ligne du dos du cheval afin d’obtenir une méthode précise, quantifiable, objective et reproductible, permettant de discriminer des populations. Pour cela, plusieurs améliorations méthodologiques (ajout de marqueurs pour dessiner le contour de laligne du dos du cheval, analyse de contour, annulation de la rotation de l’encolure) ont été testées sur un important jeu de données et finalement retenues. Cette méthodologie retenue a ensuite été utilisée afin de valider sa pertinence, et de rechercher des postures associées à des états de mal-être et à des conditions de travail différentes. Nos résultats ont tout d’abord mis en évidence l’existence d’une posture atypique, dans l’ensemble plate, voire creuse, associée à des marqueurs de mal-être parmi les chevaux de centre équestre. D’une part des chevaux issus de différentes disciplines équestres, et d’autre part des individus entrainés pour les courses de galop par plusieurs entraineurs, aux pratiques distinctes, ont permis d’observer un effet du type de travail sur la ligne du dessus notamment sur la forme de la croupe, del’encolure et du garrot. La méthodologie ainsi validée, il était possible de proposer un protocole de mesure de la posture par morphométrie géométrique chez l’humain, pour une application à l’étude de la communication non verbale, à la constitution d’un répertoire de postures « normales », ou encore pour le diagnostic de pathologies physiques (e.g. contextesportif) ou psychologiques. / The first goal of this thesis work was to develop the study methodology of the posture based on geometric morphometrics. This required an upgrading of the already existing methodology using the upper line of the horse in order to obtain a precise, quantifiable, unbiased and reproducible method which allows to discriminate populations. To achieve this, manymethodological improvements (addition of markers for the modelling of the contour of horse upper line, contour analyses, cancellation of the neck rotation) has been tested on a very large dataset and retained. Then this adopted methodology has been used to validate its relevance, and searching for postures associated with poor welfare and different working conditions. Our results has first brought to light the existence of an atypical posture, globally flat, even hollow, related to poor welfare indicators among the population of riding school horses. On one side horses from different equestrian disciplines, and on the other side individuals trained for horseracing by several trainers with distinct practices, has allowed to observe an impact of the type of work on the upper line, notably on the shape of the croup, neck and withers. This methodology thereby validated, it was possible to propose a protocol for the measure of the posture through geometric morphometrics on humans, for an application in the non-verbal communication research, the creation of a repertoire of « normal » postures, or for the diagnosis of psychological or physical pathologies (e.g. in the sport context).

Ce travail porte sur l'attention chez le cheval domestique. Il vise, dans un premier temps, à évaluer les capacités d'attention des chevaux grâce au développement d'outils de mesure. Nous avons ainsi développé deux tests comportementaux permettant d'évaluer respectivement l'attention visuelle (e.g. test d'attention visuelle, VAT) et auditive (e.g. test de diffusion de sons inhabituels, AAT). Les résultats montrent que ces tests comportementaux permettent la mesure de caractéristiques attentionnelles stables au cours du temps et prédictives de l'attention (i.e. VAT) et de la distractibilité (i.e. AAT) du cheval dans d'autres contextes, à savoir lors d'un test d'attention communément utilisé chez d'autres espèces (the ''5-choice serial reaction time task''), mais aussi en contexte non expérimental comme lors du travail (e.g. exercice à la longe, en reprise). Nos résultats montrent, par ailleurs, des variations individuelles d'attention d'ordre qualitatif (structuration et niveau de l'attention) et quantitatif (durée d'attention). Dans un second temps, nous avons examiné certains facteurs de modulation (intrinsèques et extrinsèques) de l'attention du cheval. Les tests développés ont alors été appliqués dans différents sites équestres. Les résultats montrent que l'attention des chevaux est modulée : i) par des facteurs intrinsèques tels que la race, le sexe des individus ou encore leur état de bien-être; et ii) par des facteurs extrinsèques tels que les conditions de vie offertes aux chevaux, le travail et particulièrement la discipline d'équitation. Enfin, nous nous sommes interrogés sur la possibilité de promouvoir l'attention du cheval au travail via des actions humaines spécifiques. Nous avons ainsi montré que l'utilisation d'une récompense alimentaire augmente rapidement l'attention du cheval sur la tâche à réaliser, et en conséquence améliore ses performances d'apprentissage, tandis que de tels effets n'ont pas été obtenus avec une « récompense » tactile. L'ensemble de ce travail permet des avancées méthodologiques novatrices pour appréhender les capacités cognitives du cheval et ses facteurs de variation. Ces résultats permettront de conseiller les utilisateurs de chevaux en termes de choix d'animaux, de gestion des séances de travail et des conditions de vie. / This study investigated attention in domestic horse. It aims, firstly, to evaluate horses’ attentional abilities by developing experimental tests. To this end, we developed behavioural visual attention (VAT) and auditory attention (AAT) tests. The results show that these behavioural tests give accurate measures of horses’ attentional characteristics. These measures are stable over time and can predict an individual’s attention (VAT) and distractibility (AAT) during another attention-testing paradigm frequently used in other species (the ‘5-choice serial reaction time task’) and in a non-experimental context: work (e.g. lunge or riding lessons). Furthermore, our results show qualitative (structure and level of attention) and quantitative (duration of attention) variations of attention between individuals. Secondly, we studied both intrinsic and extrinsic factors modulating attention in horses. The tests developed have been used across several equestrian sites. Horses’ attention appears to be modulated by: i) intrinsic factors such as an individual’s breed, gender or welfare state and ii) by extrinsic factors such as an individual’s living condition, work and especially the riding discipline. We finally investigated the possibility of promoting horses’ attention while working via dedicated human actions. We showed that using food rewards rapidly increases horses’ attention on the task and, as a consequence, improves their learning performances. These effects were not found with tactile ‘reward’. In summary, this work has led to innovative methodological improvements to assess horses’ cognitive abilities and the factors influencing them. These results have useful applications to guide horse-handlers through animal selection, work session management and choosing optimised living conditions.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

: L’économie de la filière équine repose aujourd’hui sur la production de chevaux athlètes performants sur le long terme. Le métabolisme de la jument gestante peut programmer le développement du poulain, sa santé à long terme et donc ses performances sportives à l’âge adulte. De nombreuses pratiques d’élevage peuvent modifier le métabolisme maternel, telles que la nutrition durant la gestation, la surnutrition durant la vie de la jument (surpoids et obésité) et le nombre de poulains produits par la jument (parité). L’objectif de ce travail était d’étudier les effets du métabolisme maternel durant la gestation sur la fonction et la structure placentaire à terme, la croissance osseuse, le métabolisme énergétique, l’inflammation systémique et le statut ostéoarticulaire des poulains en croissance. Un premier modèle de perturbation nutritionnelle en fin de gestation a été développé en comparant des juments ayant ingéré uniquement des fourrages au cours de la gestation ou bien des fourrages et des concentrés à partir de la mi-gestation. Ce modèle a permis de montrer que la supplémentation en concentrés altérait le métabolisme glucidique maternel, la fonction placentaire ainsi que le statut ostéoarticulaire et la réponse métabolique à un challenge de surnutrition chez le poulain. D’autre part, une perte d’état trop importante associée à une qualité/quantité de foin insuffisante entrainait un retard de maturité des fonctions de métabolisme énergétique et de reproduction mâle chez les poulains. Un deuxième modèle a ensuite été développé pour étudier l’effet de la primiparité. Cette étude a confirmé que la croissance fœtale des poulains issus des juments primipares était réduite et que ces poulains demeuraient plus petits avec un métabolisme glucidique et une maturation testiculaire retardés par rapport aux poulains issus de juments multipares. Le troisième modèle développé s’est intéressé à l’effet de l’obésité maternelle dès la conception. En effet, la prévalence de surpoids et d’obésité est de plus en plus importante au sein de la filière équine. Ce dernier modèle a permis de montrer que l’obésité maternelle associée à une résistance à l’insuline et une inflammation systémique augmentées entrainait une augmentation de la résistance à l’insuline, de l’inflammation systémique et du développement de lésions d’ostéochondrose chez les poulains. L'ensemble de ces résultats met en avant la relation entre la résistance à l’insuline maternelle, l’inflammation maternelle et le développement de lésions d’ostéochondrose chez les poulains durant la croissance, mais également entre sous-nutrition utérine et retard de maturité. Ces observations vont permettre de développer de nouvelles recommandations nutritionnelles pour les poulinières. / The economy of the equine industry is based on the production of high performance athlete horses. The metabolism of the pregnant mare can program the development of the foal, its long-term health and therefore its athletic performance at adulthood. Many breeding practices can modify maternal metabolism, such as nutrition during pregnancy, overnutrition during the mare's productive life (overweight and obesity) and the number of foals produced by the mare (parity). The aim of this work was to study the effects of maternal metabolism during pregnancy on placental function and structure, as well as bone growth, energy metabolism, systemic inflammation and osteoarticular status in growing foals. In a first approach, mares fed with forage only during gestation were compared to mares fed forage and concentrates from mid-gestation. Supplementation with concentrates altered maternal carbohydrate metabolism and placental function. In weaned foals, the osteoarticular status and the metabolic response to an overnutrition were also affected by the use of concentrates in maternal nutrition. Conversely, mares fed forage only lost body condition, which led to a delay in the post-natal maturation in terms of energy metabolism and testicular function in foals. In a second approach, the effect of primiparity was studied. Foals born to primiparous mares were growth restricted at birth and had a long-term maturational delay in bone growth, carbohydrate metabolism and testicular function. Finally, given the current high prevalence of overweight and obesity in the equine species, the effects of maternal obesity were studied. Maternal obesity associated with increased maternal insulin resistance and systemic inflammation resulted in increased insulin resistance, systemic inflammation, and increased incidence of osteochondrosis in foals. Altogether, these results highlight the relationship between maternal insulin resistance, maternal inflammation and the development of osteochondrosis lesions in foals during growth, but also between in utero undernutrition and maturation delay. These observations will contribute to adjust nutritional recommendations to broodmares.