The physiological consequences of crib-biting in horses in response to an ACTH challenge test

Stereotypies are repetitive and relatively invariant patterns of behavior, which are observed in a wide range of species in captivity. Stereotypic behavior occurs when environmental demands produce a physiological response that, if sustained for an extended period, exceeds the natural physiological regulatory capacity of the organism, particularly in situations that include unpredictability and uncontrollability. One hypothesis is that stereotypic behavior functions to cope with stressful environments, but the existing evidence is contradictory. To address the coping hypothesis of stereotypies, we triggered physiological reactions in 22 horses affected by stereotypic behavior (crib-biters) and 21 non-crib-biters (controls), using an ACTH challenge test. Following administration of an ACTH injection, we measured saliva cortisol every 30 min and heart rate (HR) continuously for a period of 3 h. We did not find any differences in HR or HR variability between the two groups, but crib-biters had significantly higher cortisol responses than controls (mean ± SD: CB, 5.84 ± 2.62 ng/ml, C, 4.76 ± 3.04 ng/ml). Moreover, crib-biters that did not perform the stereotypic behavior during the 3- h test period (Group B) had significantly higher cortisol levels than controls, which was not the case of crib-biters showing stereotypic behavior (Group A) (A, 5.58 ± 2.69 ng/ml; B, 6.44 ± 2.38 ng/ml). Our results suggest that crib-biting is a coping strategy that helps stereotypic individuals to reduce cortisol levels caused by stressful situations. We conclude that preventing stereotypic horses from crib-biting could be an inappropriate strategy to control this abnormal behavior, as it prevents individuals from coping with situations that they perceive as stressful.PostprintPeer reviewe

Stereotypic horses (Equus caballus) are not cognitively impaired

Stereotypies in animals are thought to arise from an interaction between genetic predisposition and sub-optimal housing conditions. In domestic horses, a well-studied stereotypy is crib-biting, an abnormal behaviour that appears to help individuals to cope with stressful situations. One prominent hypothesis states that animals affected by stereotypies are cognitively less flexible compared to healthy controls, due to sensitization of a specific brain area, the basal ganglia. The aim of this study was to test this hypothesis in crib-biting and healthy controls, using a cognitive task, reversal learning, which has been used as a diagnostic for basal ganglia dysfunction. The procedure consisted of exposing subjects to four learning tasks; first and second acquisition, and their reversals. For each task, we measured the number of trials to reach criterion and heart rate and heart-rate variability. Importantly, we did not try to prevent crib-biters from executing their stereotypic behaviour. We found that the first reversal learning task required the largest number of trials, confirming its challenging nature. Interestingly, the second reversal learning task required significantly fewer trials to reach criterion, suggesting generalisation learning. However, we did not find any performance differences across groups; both stereotypic and control animals required a similar numbers of trials and did not differ in their physiological responses. Our results thus challenge the widely held belief that crib-biting horses, and stereotypic animals more generally, are cognitively impaired. We conclude that cognitive underperformance may occur in stereotypic horses if they are prevented from crib-biting to cope with experienced stress.PostprintPeer reviewe

Effects of long-term exposure to an electronic containment system on the behaviour and welfare of domestic cats

Free-roaming cats are exposed to a variety of risks, including involvement in road traffic accidents. One way of mitigating these risks is to contain cats, for example using an electronic boundary fence system that delivers an electric ‘correction’ via a collar if a cat ignores a warning cue and attempts to cross the boundary. However, concerns have been expressed over the welfare impact of such systems. Our aim was to determine if long-term exposure to an electronic containment system was associated with reduced cat welfare. We compared 46 owned domestic cats: 23 cats that had been contained by an electronic containment system for more than 12 months (AF group); and 23 cats with no containment system that were able to roam more widely (C group). We assessed the cats’ behavioural responses and welfare via four behavioural tests (unfamiliar person test; novel object test; sudden noise test; cognitive bias test) and an owner questionnaire. In the unfamiliar person test, C group lip-licked more than the AF group, whilst the AF group looked at, explored and interacted more with the unfamiliar person than C group. In the novel object test, the AF group looked at and explored the object more than C group. No significant differences were found between AF and C groups for the sudden noise or cognitive bias tests. Regarding the questionnaire, C group owners thought their cats showed more irritable behaviour and AF owners thought that their cats toileted inappropriately more often than C owners. Overall, AF cats were less neophobic than C cats and there was no evidence of significant differences between the populations in general affective state. These findings indicate that an electronic boundary fence with clear pre-warning cues does not impair the long term quality of life of cat

Stereotypic behaviour in horses lowers stress but not spatial learning performance

International audienceStereotypies are common in captive animals, but it remains unclear if they are pathological by-products of captive conditions or if they have an adaptive function. Here, we address this question using crib-biting, a common type of stereotypic behaviour in domestic horses, thought to result from stressful or frustrating envi- ronments. Since chronic stress is known to affect learning abilities via dopaminergic modulation in the basal ganglia, we predicted that stereotypic horses would underperform in learning tasks compared to healthy control animals, in line with the pathological by-product hypothesis. We exposed 19 crib-biters and 18 control horses in six spatial tasks, and collected behavioural and physiological data (heart rate, heart rate variability and salivary cortisol) to assess learning performance and stress levels. We found that, during the learning phase, 10 of 19 crib- biters showed stereotypic behaviourSurprisingly, crib-biters that displayed the stereotypic behaviour (Group A) had lower salivary cortisol values compared to crib-biters that did not display the stereotypic behaviour (Group B) or control horses. (Group C) after the first part of the experiment. In addition, a smaller proportion of horses in Group A displayed behaviours indicating frustration during one of the test compared to Group B. Moreover, we found no difference between the three groups in their learning performance nor in their heart rate or heart rate variability measures. Our results therefore suggest that crib-biting has an adaptive function and can help horses to reduce stress and frustration during learning tasks, which then enables them to show normal learning performanc

Appréciation de la personnalité du cheval FM par des tests standardisés : étude préliminaire au projet de phénotypage visant à identifier des gènes de tempérament

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Assessment of Franches-Montagnes (FM) horse personality by standardized tests: a first step towards the identification of behavioural trait genes

National audienc