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23 novembre 2008
Coping with fear and stress: licking and yawning
Steven R. Lindsay
Handbook of applied dog behavior and training


Tous les articles sur la contagion du bâillement
All articles about contagious yawning
Voith and Borchelt (1996) have observed that licking and yawning often occur in situations involving conflict and stress. Dogs that are uneasy or fearful of approach often exhibit licking and lick-intention movements. They have also observed that yawning appears to occur in conflict situations involving a delay gratification or frustration (e.g. waiting to be let outdoors). Licking activity may become an exaggerated or compulsive self-directed behavior, sometimes resulting in lesions to the legs. They report that when a dog is restrained and exposed to an uneventful social situation in which it feels uneasy or fearful, it may involuntarily doze while sitting, or lying down (sternal recumbency). Such dogs appear to fight an urge to doze that develops over time in the situation, finally losing muscle tone ans slipping briefly into sleep, whereupon they start and awaken to continue the vigil. Such dogs appear conflicted between a need to maintain alertness and an opposing urge to fall asleep.
Yawning is common in similar situations of declining attention requering an increased level of arousal and alertness. Dogs may yawn when forced to practice repetitive and monotonus training exercices, such as repeated sit-way behaviors. In some of these dogs, yawning appears to present with penile erections, but it is not clear whether the erection are causally linked with the act of yawning or simply part of coping response to such situations. Whether such dogs are stressed, bored, drowsy, or all three is debatable, but trainers can avoid such tedium by keeping their training sessions brief, reward dense, and playful. Yawning probably performs a cognitive-enhancement function by boosting ebbing attention under conditions in which the dog must continue to wait or defer. Similarly, yawning may help to mediate adjustments in response to unsettling social situations requiring that the dog maintain alertness while at the same time remaining inconspicuous and inactive. Yawning may also occur under certain fear-eliciting social situations. For example, Beerda and colleagues (1998) reported that yawning and stress-related oral activities (e.g. licking movements) occured in association with fear produced by restraint or startle, but only if a person was present. These findings suggets that at least some strees-related yawning and licking may be expressed with a social intent (appeasement signal) that might not occur (or occur les frequently) in absence of an appropriate social object. In addition, licking may perform a displacement or cut-off function, perhaps used to appease or pacify the approaching person or dog. A pacifying function has been attribuated to canine yawning, including a host of other sociosexual communication functions (Abrantes, 1977) and a controversial calming or reassuring effect that is purportedly induced when an owner yawns at a distressed dogs (Rugass, 1997).
In humans, yawning is partially involuntary, socially contagious, and appears to increase alertness and arousal (Baenninger, 1996). Once yawning begins, it is often repeated and may facilitate yawning by others nearby , suggesting the possibility that it exerts a remote contagion effect via observation; however, merely thinking about yawning can also evoke the response. Altough an increase in oxygen/carbon dioxide exchange in the lungs has been proposed, the actual physiological function of yawning has not yet been determined. Yawning is phylogenetically ancient and is under the control of a variety of neurotransmitter systems and interactions, including stress-sensitive acetylcholine and dopamine pathways. Circulating glucocorticoids and others neuropeptides (ACTH, prolactin) exert a facilitative effect on yawning consistent with a stress-related function. Dopamine appears to play a prominent role in the stress-related evocaton of yawning via the release of oxytocin at the level of the paraventricular nucleus of the hypothalamus, which subsequently activates an oxyticinergic pathway projecting to the hippocampus (Argiolas, 1998), a potentially significant link-age mediating the social contagion effects of yawning.
The multifaced role of central oxytocin in the expression of sexual behavior (perhaps explaining the occurrence of stress-related penile erections), social recognition,attachement and bonding, and the diminution of irritability and agression, suggests that yawning may help to modulate aversive emotional arousal produced in association with stressful social interaction. Among olive baboons, anxious yawning and other self-direct behaviors (e.g. touching, scratching, grooming, and shaking) increase approximatively 40% if the closest group member (whithin 5 meters) is dominant, which suggest that such anxious behavior may sometimes possess a social siginificance. Yawning may increase attention in social transitions requiring inactivity and deference, while at the same time helping to reduce social anxiety and agressive arousal by producing incompatible cogntive and emotinal changes via the release of oxytocin (e.g. enhanced social recognition) and other neural changes conductive to peaceful social transactions. Dogs can be trained to yawn by means of instrumental techniques (Konorsky, 1967), which suggests the possibility thatt the response might be infuenced by learning and used in some instances as a deliberat signal to indicate a readiness for increased activity, waning patience, or other information. Many dogs exhibit yawns that include drawn-out high-pitched squeaking or abbreviated highpitched howl-like sounds that conclude with chomping or clacking sounds with a sigh of apparent exasperation. Such variations in canin yawning may be produced with a signaling intent, depending on the situational occur. Audible squeaks , chomps or clacks, and sighs may be used to draw the owner's attention to the yawn and to help clarify its significance, perhaps resulting in its periodic reinforcement.
Licking and lick intention movements serve a significant canine social communication function when performed in the context of appeasement and care-seeking situations, but it is not clear whether licking actions performed by a person toward a fearful or stressed dog serve to produce a calming or reassuring effect or any effect at all. In the case of yawning, given its complex neurobiological nature and close association with the central release of oxytocin, one might best keep an open mind with regard to its potential value as a social signal and capacity for inducing a calming or pacifying effect. Casual experiments by Steven Lindsay to test the calming-signal hypothesis (i.e. the belief that yawning or licking might produce a calming effect in dogs) were without consistent effect, but some dogs do respond to human licking by licking back in turn, by averting their gaze or head, by backing away, or by yawning in response to repeated licking actions, which raises the possibility that such signals might actually produce a mildly aversive effect in dog's attention repeatedly or petting it may produce a calming effect of variable strength. As a result, some caution should be exercised in suggesting that such signals have special calming properties, particularly when used arbitrarily and out of context.

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Coping with fear and stress: licking and yawning
SR. Lindsay
Handbook of applied dog behavior and training 2000
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