Impulsive for life? The nature of long-term impulsivity in domestic dogs

Individual differences in impulsivity occur at a cognitive and/or behavioural level and are associated with differing life outcomes. However, there is a lack of empirical evidence to support the long-term stability of these characteristics in non-human animals. This study reports on the stability of convergent measures of impulsivity in domestic dogs assessed more than 6 years apart. Measures were (1) owner assessment by means of a questionnaire, the validated 'Dog Impulsivity Assessment Scale' (DIAS) and (2) dogs' performance in a delayed reward choice test. Dogs had 15-min free access to two food dispensers, one dispensing a piece of food immediately, the other dispensing three pieces after a delay, which increased by 1 s every other time the dogs sampled it. Maximum delay reached in this task reflects decision-making, or cognitive impulsivity, whereas the rate of extra presses on the delayed reward device during the delay can be considered as a measure of motor or behavioural impulsivity. DIAS scores were strongly and significantly correlated across years. The maximum delay reached in the behaviour test was also highly stable, whereas paw-pressing rate was uncorrelated between the years. These results demonstrate that cognitive but not motor impulsivity is highly consistent over time in dogs.

Canine olfactory detection of malignant melanoma

Our patient is a 75-year-old man who presented after his pet dog licked persistently at an asymptomatic lesion behind his right ear. Examination revealed a nodular lesion in the postauricular sulcus. Histology confirmed malignant melanoma, which was subsequently excised. Canine olfactory detection of human malignancy is a well-documented phenomenon. Advanced olfaction is hypothesised to explain canine detection of bladder, breast, colorectal, lung, ovarian, prostate and skin cancers. Further research in this area may facilitate the development of a highly accurate aid to diagnosis for many malignancies, including melanoma.

Deferred imitation and declarative memory in domestic dogs

This study demonstrates for the first time deferred imitation of novel actions in dogs (Canis familiaris) with retention intervals of 1.5 min and memory of familiar actions with intervals ranging from 0.40 to 10 min. Eight dogs were trained using the 'Do as I do' method to match their own behaviour to actions displayed by a human demonstrator. They were then trained to wait for a short interval to elapse before they were allowed to show the previously demonstrated action. The dogs were then tested for memory of the demonstrated behaviour in various conditions, also with the so-called two-action procedure and in a control condition without demonstration. Dogs were typically able to reproduce familiar actions after intervals as long as 10 min, even if distracted by different activities during the retention interval and were able to match their behaviour to the demonstration of a novel action after a delay of 1 min. In the two-action procedure, dogs were typically able to imitate the novel demonstrated behaviour after retention intervals of 1.5 min. The ability to encode and recall an action after a delay implies that facilitative processes cannot exhaustively explain the observed behavioural similarity and that dogs' imitative abilities are rather based on an enduring mental representation of the demonstration. Furthermore, the ability to imitate a novel action after a delay without previous practice suggests presence of declarative memory in dogs.

Extended suicide with a pet

The combination of the killing of a pet and a suicide is a perplexing scenario that is largely unexplored in the literature. Many forensic psychiatrists and psychologists may be unaccustomed to considering the significance of the killing of a pet. The subject is important, however, because many people regard their pets as members of their family. A case is presented of a woman who killed her pet dog and herself by carbon monoxide poisoning. The purpose of this article is to provide an initial exploration of the topic of extended suicide with a pet. Forensic mental health evaluations may have a role in understanding the etiology of this event and in opining as to the culpability of individuals who attempt to or successfully kill a pet and then commit suicide. Because the scientific literature is lacking, there is a need to understand this act from a variety of perspectives. First, a social and anthropological perspective will be presented that summarizes the history of the practice of killing of one's pet, with a focus on the ancient Egyptians. A clinical context will examine what relationship animals have to mental illness. A vast body of existing scientific data showing the relevance of human attachment to pets suggests that conclusions from the phenomena of homicide-suicide and filicide-suicide are applicable to extended suicide with a pet. Finally, recommendations will be proposed for both clinical and forensic psychiatrists faced with similar cases.

Dogs' attention towards humans depends on their relationship, not only on social familiarity

Both in humans and non-human animals, it has been shown that individuals attend more to those they have previously interacted with and/or they are more closely associated with than to unfamiliar individuals. Whether this preference is mediated by mere social familiarity based on exposure or by the specific relationship between the two individuals, however, remains unclear. The domestic dog is an interesting subject in this line of research as it lives in the human environment and regularly interacts with numerous humans, yet it often has a particularly close relationship with its owner. Therefore, we investigated how long dogs (Canis familiaris) would attend to the actions of two familiar humans and one unfamiliar experimenter, while varying whether dogs had a close relationship with only one or both familiar humans. Our data provide evidence that social familiarity by itself cannot account for dogs' increased attention towards their owners since they only attended more to those familiar humans with whom they also had a close relationship.

Dogs' social referencing towards owners and strangers

Social referencing is a process whereby an individual uses the emotional information provided by an informant about a novel object/stimulus to guide his/her own future behaviour towards it. In this study adult dogs were tested in a social referencing paradigm involving a potentially scary object with either their owner or a stranger acting as the informant and delivering either a positive or negative emotional message. The aim was to evaluate the influence of the informant's identity on the dogs' referential looking behaviour and behavioural regulation when the message was delivered using only vocal and facial emotional expressions. Results show that most dogs looked referentially at the informant, regardless of his/her identity. Furthermore, when the owner acted as the informant dogs that received a positive emotional message changed their behaviour, looking at him/her more often and spending more time approaching the object and close to it; conversely, dogs that were given a negative message took longer to approach the object and to interact with it. Fewer differences in the dog's behaviour emerged when the informant was the stranger, suggesting that the dog-informant relationship may influence the dog's behavioural regulation. Results are discussed in relation to studies on human-dog communication, attachment, mood modification and joint attention.

Dogs (Canis familiaris) evaluate humans on the basis of direct experiences only

Reputation formation is a key component in the social interactions of many animal species. An evaluation of reputation is drawn from two principal sources: direct experience of an individual and indirect experience from observing that individual interacting with a third party. In the current study we investigated whether dogs use direct and/or indirect experience to choose between two human interactants. In the first experiment, subjects had direct interaction either with a “nice” human (who played with, talked to and stroked the dog) or with an “ignoring” experimenter who ignored the dog completely. Results showed that the dogs stayed longer close to the “nice” human. In a second experiment the dogs observed a “nice” or “ignoring” human interacting with another dog. This indirect experience, however, did not lead to a preference between the two humans. These results suggest that the dogs in our study evaluated humans solely on the basis of direct experience.

Can domestic dogs (Canis familiaris) use referential emotional expressions to locate hidden food?

Although many studies have investigated domestic dogs' (Canis familiaris) use of human communicative cues, little is known about their use of humans' emotional expressions. We conducted a study following the general paradigm of Repacholi in Dev Psychol 34:1017-1025, (1998) and tested four breeds of dogs in the laboratory and another breed in the open air. In our study, a human reacted emotionally (happy, neutral or disgust) to the hidden contents of two boxes, after which the dog was then allowed to choose one of the boxes. Dogs tested in the laboratory distinguished between the most distinct of the expressed emotions (Happy-Disgust condition) by choosing appropriately, but performed at chance level when the two emotions were less distinct (Happy-Neutral condition). The breed tested in the open air passed both conditions, but this breed's differing testing setup might have been responsible for their success. Although without meaningful emotional expressions, when given a choice, these subjects chose randomly, their performance did not differ from that in the experimental conditions. Based on the findings revealed in the laboratory, we suggest that some domestic dogs recognize both the directedness and the valence of some human emotional expressions.

Dog bite risk: an assessment of child temperament and child-dog interactions

Annually approximately 400,000 American children receive treatment for dog bites. Young children are at greatest risk and are frequently bitten following behavior that provokes familiar dogs. This study investigated the effects of child temperament on children’s interaction with dogs. Eighty-eight children aged 3.5–6 years interacted with a live dog. Dog and child behaviors were assessed through observational coding. Four child temperament constructs—impulsivity, inhibitory control, approach and shyness—were assessed via the parent-report Children’s Behavioral Questionnaire. Less shy children took greater risks with the dog, even after controlling for child and dog characteristics. No other temperament traits were associated with risk-taking with the dog. Based on these results, children’s behavior with unfamiliar dogs may parallel behavior with other novel or uncertain situations. Implications for dog bite intervention programs include targeting at-risk children and merging child- and parent-oriented interventions with existing programs geared toward the physical environment and the dog.

Functional MRI in awake unrestrained dogs

Because of dogs' prolonged evolution with humans, many of the canine cognitive skills are thought to represent a selection of traits that make dogs particularly sensitive to human cues. But how does the dog mind actually work? To develop a methodology to answer this question, we trained two dogs to remain motionless for the duration required to collect quality fMRI images by using positive reinforcement without sedation or physical restraints. The task was designed to determine which brain circuits differentially respond to human hand signals denoting the presence or absence of a food reward. Head motion within trials was less than 1 mm. Consistent with prior reinforcement learning literature, we observed caudate activation in both dogs in response to the hand signal denoting reward versus no-reward.

Do dogs (Canis lupus familiaris) make counterproductive choices because they are sensitive to human ostensive cues?

Dogs appear to be sensitive to human ostensive communicative cues in a variety of situations, however there is still a measure of controversy as to the way in which these cues influence human-dog interactions. There is evidence for instance that dogs can be led into making evaluation errors in a quantity discrimination task, for example losing their preference for a larger food quantity if a human shows a preference for a smaller one, yet there is, so far, no explanation for this phenomenon. Using a modified version of this task, in the current study we investigated whether non-social, social or communicative cues (alone or in combination) cause dogs to go against their preference for the larger food quantity. Results show that dogs' evaluation errors are indeed caused by a social bias, but, somewhat contrary to previous studies, they highlight the potent effect of stimulus enhancement (handling the target) in influencing the dogs' response. A mild influence on the dog's behaviour was found only when different ostensive cues (and no handling of the target) were used in combination, suggesting their cumulative effect. The discussion addresses possible motives for discrepancies with previous studies suggesting that both the intentionality and the directionality of the action may be important in causing dogs' social biases.

[Castration of dogs from the standpoint of behaviour therapy]

The castration of dogs is an amputation covered by Section 6 (1) of the Animal Protection Law in Germany. Apart from the general indications given by veterinary medicine, castration of an animal is a potential method of animal behaviour therapy. However, the highly variable, individual effects of castration on behaviour require detailed diagnosis by the veterinarian. Castration appears to exert its strongest influence on sexually dimorphic behaviour patterns in male dogs, e.g. status- related aggression, urine marking, mounting, house-soiling problems, and roaming. An indication to castrate a bitch is maternal aggression. When evaluating the effects of castration, one should always consider individual circumstances, such as learning experience (for example in the case of "experienced copulators"), age, and pack behaviour (if there is more than one dog in the household). Additional benefits of castration include a reduction in the dog's general activity level, decreased preparatory arousal and a decline in the dog's ability to focus its attention fully on the target of attack. As a result, it is much easier for the owner to disrupt and manage or control the dog's agonistic intentions. However, castration is not the ultimate remedy in dog-handling. Any decision in this respect should be based on a precise behaviour- related indication. Otherwise, such surgery may well violate the Animal Protection Law.

Dogs (Canis familiaris), but not chimpanzees (Pan troglodytes), understand imperative pointing

Chimpanzees routinely follow the gaze of humans to outside targets. However, in most studies using object choice they fail to use communicative gestures (e.g. pointing) to find hidden food. Chimpanzees' failure to do this may be due to several difficulties with this paradigm. They may, for example, misinterpret the gesture as referring to the opaque cup instead of the hidden food. Or perhaps they do not understand informative communicative intentions. In contrast, dogs seem to be skilful in using human communicative cues in the context of finding food, but as of yet there is not much data showing whether they also use pointing in the context of finding non-food objects. Here we directly compare chimpanzees' (N = 20) and dogs' (N = 32) skills in using a communicative gesture directed at a visible object out of reach of the human but within reach of the subject. Pairs of objects were placed in view of and behind the subjects. The task was to retrieve the object the experimenter wanted. To indicate which one she desired, the experimenter pointed imperatively to it and directly rewarded the subject for handing over the correct one. While dogs performed well on this task, chimpanzees failed to identify the referent. Implications for great apes' and dogs' understanding of human communicative intentions are discussed.

Two-item sentence comprehension by a dog (Canis familiaris)

Syntax use by non-human animals remains a controversial issue. We present here evidence that a dog may respond to verbal requests composed of two independent terms, one referring to an object and the other to an action to be performed relative to the object. A female mongrel dog, Sofia, was initially trained to respond to action (point and fetch) and object (ball, key, stick, bottle and bear) terms which were then presented as simultaneous, combinatorial requests (e.g. ball fetch, stick point). Sofia successfully responded to object-action requests presented as single sentences, and was able to flexibly generalize her performance across different contexts. These results provide empirical evidence that dogs are able to extract the information contained in complex messages and to integrate it in directed performance, an ability which is shared with other linguistically trained animals and may represent a forerunner of syntactic functioning.

Domestic dogs (Canis familiaris) flexibly adjust their human-directed behavior to the actions of their human partners in a problem situation

Domestic dogs (Canis familiaris) have been shown to actively initiate triadic communicative interactions by looking at a human partner or by alternating their gaze between the human and an object when being faced with an out-of-reach reward or an unsolvable problem. It has hardly been investigated, however, whether dogs flexibly adjust their human-directed behavior to the actions of their partners, which indicate their willingness and abilities to help them when they are faced with a problem. Here, in two experiments, we confronted dogs-after initially allowing them to learn how to manipulate an apparatus-with two problem situations: with an empty apparatus and a blocked apparatus. In Experiment 1, we showed that dogs looked back at their owners more when the owners had previously encouraged them, independently from the problem they faced. In Experiment 2, we provided dogs with two experimenters and allowed them to learn through an initial phase that each of the experimenters could solve one of the two problems: the Filler re-baited the empty apparatus and the Helper unblocked the blocked apparatus. We found that dogs could learn to recognize the ability of the Filler and spent time close to her when the apparatus was empty. Independently from the problem, however, they always approached the Helper first. The results of the present study indicate that dogs may have a limited understanding of physical problems and how they can be solved by a human partner. Nevertheless, dogs are able to adjust their behavior to situation-specific characteristics of their human partner's behavior.

Controlled but pragmatic investigations of interventions for behavioural disturbances in dogs and cats

Veterinarians are often directly involved in clinical studies or requested for information to help interpret their results. Therefore, it is reasonable to examine the reservoir of study methods. This article transfers methodological considerations from clinical research into veterinary medicine. The study question determines the appropriate study method. Recently a ten-step procedure was suggested for selection of appropriate study designs in humans. Based on this approach, a pragmatic study design was adapted to the conditions prevailing in interventional studies in dogs and cats with disturbed behaviour. The different concepts for clinical studies are introduced. Whether or not the design and the evaluation of pragmatic studies in dogs and cats with disturbed behaviour has been maintained and the prerequisites have thereby been fulfilled so that the obtained results are suitable to be applied under everyday conditions can be tested in eight steps. Using the pragmatic design the superiority of complex interventions can be investigated. The results of pragmatic studies help to substantiate a value judgement, i. e., the recommendation or rejection of a specific therapeutic intervention for a defined disease entity in a specific therapeutic setting. The goal of pragmatic studies is to obtain results appropriate for use in everyday situations. In conclusion, the suggested procedure is useful for the selection of the appropriate study designs for specific questions. This procedure is also suitable to test whether the conclusions of published study results coincide with the chosen methods.