Abstract: Habronema microstoma and Habronema muscae (Spirurida: Habronematidae) are parasitic nematodes which infect the stomach and/or skin of equids. The accurate diagnosis of gastric habronemosis is central to studying its epidemiology, but data on its distribution and prevalence are lacking, mainly due to the limitations of clinical and coprological diagnosis in live horses. To overcome this constraint, a two-step, semi-nested PCR-based assay was validated (utilizing genetic markers in the nuclear ribosomal DNA) for the specific amplification of H. microstoma or H. muscae DNA from the faeces from horses (n = 46) whose gastrointestinal parasite status had been determined at autopsy and whose faeces were examined previously using a conventional parasitological approach. Of these horses examined at autopsy, some harboured adults of either H. microstoma (n= 19) or H. muscae (n =4), and others (n = 7) harboured both species. Most of them were also infected with other parasites, including strongylid nematodes (subfamilies Cyathostominae and Strongylinae), bots and/or cestodes; there was no evidence of metazoan parasites in 2 horses. Larvated spirurid eggs were detected in the faeces of 1 of the 30 horses (3.3 %) shown to be infected with Habronema at autopsy. For this set of 46 samples, the PCR assay achieved a diagnostic specificity of 100 % and a sensitivity of approximately 97 % (being able to specifically detect as little as approximately 0.02 fg of Habronema DNA). The specificity of the assay was also tested using a panel of control DNA samples representing horse, the gastric spirurid Draschia megastoma and 26 other species of parasites from the alimentary tract of the horse. H. microstoma, H. muscae and D. megastoma could be readily differentiated from one another based on the sizes of their specific amplicons in the PCR. The results of this study showed that the performance of the PCR for the diagnosis of gastric habronemosis was similar to that of autopsy but substantially better than the traditional coprological examination procedure used. The ability to specifically diagnose gastric habronemosis in equids should have important implications for investigating the epidemiology and ecology of H. microstoma and H. muscae.

Abstract: The genus Thelazia (Spirurida, Thelaziidae) includes a cosmopolitan group of eyeworm spirurids responsible for ocular infections in domestic and wild animals and transmitted by different species of muscids. Bovine thelaziosis is caused by Thelazia rhodesi Desmarest 1828, Thelazia gulosa Railliet & Henry 1910, and Thelazia skrjabini Erschow 1928, which occur in many countries; T. gulosa and T. skrjabini have been reported mainly in the New World, while T. rhodesi is particularly common in the Old World. In Italy, T. rhodesi was reported in southern regions a long time ago and, recently, T. gulosa and T. skrjabini have been identified in autochthonous cattle first in Apulia and then in Sardinia. Thirteen species of Musca are listed as intermediate hosts of eyeworms, but only Musca autumnalis and Musca larvipara have been demonstrated to act as vectors of Thelazia in the ex-URSS, North America, ex-Czechoslovakia and more recently in Sweden. In Italy, after the reports of T. gulosa and T. skrjabini in southern regions, the intermediate hosts of bovine eyeworms were initially only suspected as the predominant secretophagous Muscidae collected from the periocular region of cattle with thelaziosis were the face flies, M. autumnalis and M. larvipara, followed by Musca osiris, Musca tempestiva and Musca domestica. The well-known constraints in the identification of immature eyeworms to species by fly dissection and also the time-consuming techniques used constitute important obstacles to epidemiological field studies (i.e. vector identification and/or role, prevalence and pattern of infection in flies, etc.). Molecular studies have recently permitted to further investigations into this area. A PCR-RFLP analysis of the ribosomal ITS-1 sequence was developed to differentiate the 3 species of Thelazia (i.e. T. gulosa, T. rhodesi and T. skrjabini) found in Italy, then a molecular epidemiological survey has recently been carried out in field conditions throughout five seasons of fly activity and has identified the role of M. autumnalis, M. larvipara, M. osiris and M. domestica as vectors of T. gulosa and of M. autumnalis and M. larvipara of T. rhodesi. Moreover, M. osiris was described, for the first time, to act as a vector of T. gulosa and M. larvipara of T. gulosa and T. rhodesi. The mean prevalence in the fly population examined was found to be 2.86%. The molecular techniques have opened new perspectives for further research on the ecology and epidemiology not only of Thelazia in cattle but also of other autochthonous species of Thelazia which have been also recorded in Italy, such as Thelazia callipaeda, which is responsible for human and canid ocular infection and Thelazia lacrymalis, the horse eyeworm whose epidemiological molecular studies are in progress.

Abstract: Lateralization of emotions has received great attention in the last decades, both in humans and animals, but little interest has been given to side bias in perceptual processing. Here, we investigated the influence of the emotional valence of stimuli on visual and olfactory explorations by horses, a large mammalian species with two large monocular visual fields and almost complete decussation of optic fibres. We confronted 38 Arab mares to three objects with either a positive, negative or neutral emotional valence (novel object). The results revealed a gradient of exploration of the 3 objects according to their emotional value and a clear asymmetry in visual exploration. When exploring the novel object, mares used preferentially their right eyes, while they showed a slight tendency to use their left eyes for the negative object. No asymmetry was evidenced for the object with the positive valence. A trend for an asymmetry in olfactory investigation was also observed. Our data confirm the role of the left hemisphere in assessing novelty in horses like in many vertebrate species and the possible role of the right hemisphere in processing negative emotional responses. Our findings also suggest the importance of both hemispheres in the processing positive emotions. This study is, to our knowledge, the first to demonstrate clearly that the emotional valence of a stimulus induces a specific visual lateralization pattern.

Abstract: Group housed horses at a stud farm/riding stable in Belgium were observed on 17 days between 21 February and 25 April 2008, totalling 54hr25min of detailed data. The original group consisted of 8 Irish Cob mares, 1 Warmblood mare, 1 Arabian gelding and 2 Arabian mares. The group had been established in December 2007. During the course of the study 5 horses were removed from the group and 2 foals were born. 3 highly pregnant mares were housed adjacent to the group for part of the period. Horses were regularly used for lessons. Available surface area differed with the group on pasture at the end. Continuous all occurrence sampling of 10 agonistic and 2 affiliative behaviours was carried out for all group members present. Overall the group showed a frequency of 44.75 agonistic interactions per hour and 11.25 affiliative per hour. Of those agonistic interactions 46.3% were threats while 47% were less active interactions (displacement, being avoided), leaving only 6.7% more aggressive interactions ( mainly biting, some kicking and chasing). The effect on acting agonistically was not significant for age (p=0.1591) and borderline significant for density (p=0.0627). The analysis of the frequency of affiliative interactions showed there is no significant effect of age (p=0.1865) or density (p=0.7923). Agonistic and affiliative interactions were not significantly correlated (p=0.72). Affiliative behaviour a horse received showed a borderline effect (p=0.0787) on agonistic behaviour, as did the interaction between received agonistic and affiliative interactions (p=0.0725). Received agonistic interactions had a borderline negative effect (p=0.0656) on affiliative behaviour. A dominance hierarchy was calculated based on agonistic interactions using Empirical Bayes’ estimates based on Poisson regression with random effects. Agonistic behaviour expressed to other horses was significantly effected by relative rank (p=0.0243). Overall horses tended to be 3.7 times more aggressive towards lower ranking horses compared to higher ranking horses. Affiliative behaviour shown to other horses was not significantly influenced by the rank of the social partner (p=0.7915). Some individuals did show a significant effect whereby they showed more affiliative behaviour towards lower ranking individuals. This study was a small project to look at a practical situation of riding horses being kept in group housing. The frequent changes in group composition and available surface made it possible to look at agonistic and affiliative interactions in such circumstances. This is useful as instability in group composition is often used as main reason not to keep horses in social groups. The results from this study showed a borderline effect of density on agonistic behaviour. In reality it was also influenced by practical details, like a narrow paddock with only 2 hay crates on the smallest surface. Rank in a dominance hierarchy, based on agonistic behaviour, had a significant effect on the agonistic behaviour expressed towards higher or lower ranking horses. No injuries or escalating fights were observed. This study shows it is possible to keep a group of riding horses in a social context without excessive aggression.