Dog owners experience a reduction in negative mood and feelings of loneliness


A new University of Sydney trial lends weight to the expression ‘man’s best friend,’ showing a sample of new dog owners saw a significant reduction in loneliness within three months of acquiring their pet.

The PAWS trial is a long-term Australian controlled study to look at dog ownership and mental wellbeing in the community, published today in BMC Public Health, followed a total of 71 Sydney-siders over an eight-month period.

It compared the mental wellbeing of new dog owners to those who intended to acquire a dog (but held off during the eight-month study period) and those who had no intention of owning a dog.

Key findings

The researchers from the University’s Charles Perkins Centre and RSPCA NSW found new dog owners self-reported lower levels of loneliness within three months of getting a dog, with the effect persisting to the end of the study.

They also found some evidence to suggest new dog owners experience a reduction in negative mood after acquiring a dog, such as being upset or scared.

But, they saw no impact on psychological distress, which includes the symptoms associated with depression and anxiety.

With 39 percent of Australian households owning a dog, lead author Ms Lauren Powell said the small trial sheds light on the potential health benefits of dog ownership.

“Some previous research has shown that human to dog interactions can have benefits in settings like nursing homes using therapy dogs, however, there is very little research looking at the impact for every-day dog owners interacting with their dog at home,” said Ms Powell, PhD candidate in the Charles Perkins Centre.

“While we can’t pinpoint exactly how dog ownership positively affected mood and loneliness in our participants, many people in the study reported that they got to know others in their neighbourhood because of their new dog.

“We also know that short-term interactions with dogs improve mood so it may be that the regular occurrence of these interactions seen with dog ownership produced long-term improvements.”

The study design also allowed researchers to minimise the possibility that people who are thinking about getting a dog may already be experiencing better mental well-being.

Why are these findings important?

Senior author Professor Emmanuel Stamatakis from the Faculty of Medicine and Health said in today’s busy world many people have lost a sense of community and social isolation is increasing.

It compared the mental wellbeing of new dog owners to those who intended to acquire a dog (but held off during the eight-month study period) and those who had no intention of owning a dog.

“If dogs can help people get out into their neighbourhoods more and to meet other people, this is a win-win,” said Stamatakis, Professor of Physical Activity, Lifestyle, and Population Health in the School of Public Health.

“This is particularly important in older age when there is an increased risk of isolation and loneliness. It’s a major cardiovascular disease risk factor, it’s a major cancer risk factor, and it’s a major risk factor for depression.”

What are the next steps?

The researchers acknowledge that the findings contrast with earlier international studies and further larger-scale trials are needed to examine the intricacies of the relationship between dog ownership and human mental health.

“This is a new and emerging area of research, particularly given everyone’s relationship with their dog is so different,”

“Finding a way to assess that and take that into account is half the challenge.”

The group is also currently conducting parallel studies looking at the impact of dog ownership on the physical activity patterns of their owners.

In collaboration with the RSPCA NSW, the Dog Ownership and Human Health Research Node at the Charles Perkins Centre brings together experts in public health, physical activity and exercise, disease prevention, behaviour change, health psychology, human-animal interactions, and canine health.

Researchers hope the node will shed light on not only how dog ownership influences human health in the community, but also on how these benefits could be harnessed as part of the health care system.

Funding: This research was supported by a research donation provided by Ms Lynne Cattell [University of Sydney grant ID: 183100].

The donor had no involvement in the study design; collection, analysis and interpretation of data; writing of the report or the decision to submit the article for publication. The authors declare that they have no competing interests.

While many people will experience traumatic events during their lifetime, only some will develop a post-traumatic stress disorder (PTSD) or related problems, while others show resilience and can cope successfully.

Certain populations are more likely to experience traumatic events, such as members of the military, firefighters, police, first aid, but also refugees or people living in war zones.

Internationally, the military is faced with an increasing number of soldiers who receive the diagnosis of PTSD and is working on improving the therapeutic interventions for this group of patients.

In the U.S., several organizations for veterans include animal assisted interventions (AAI), usually with horses or dogs, in their treatment programs, to alleviate symptoms of PTSD and to improve quality of life.

Only few studies on the effects of AAI for PTSD in general, and for PTSD in veterans in particular, exist today.

Therefore, a pilot project of the German military (Deutsche Bundeswehr) to support standard therapy for soldiers with PTSD via a short-term dog-assisted intervention was developed and evaluated; both will be reported here.

A brief introduction into the symptoms of PTSD and their treatment is given, followed by a short overview of effects of AAI in general and for PTSD.

Also, possible underlying mechanisms explaining potential positive effects of human-animal interactions are addressed, prior to the report of the actual dog-assisted intervention and study.

Post-traumatic Stress Disorder

PTSD—Symptoms and Prevalence

In the DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th revision, APA) the acute stress disorder (ASD), also called acute stress reaction (ASR), and the post-traumatic stress disorder (PTSD) are both described as reactions toward a traumatic event.

The acute stress disorder describes an acute stress reaction directly after a stressful, or even traumatic, experience and, in some cases, may also be present as a pre-stage of PTSD. For both diagnoses, the event needs to meet certain criteria to be considered traumatic.

There is a wide variety of potentially traumatic experiences, including sexual or physical abuse, natural disasters, war, respectively large-scale acts of violence or accidents.

For the diagnosis of PTSD, the experience must have included exposure to death or threat of death for oneself or others or the violation of one’s physical integrity. The experience of the event must have been direct and accompanied by feelings of horror, fear and helplessness, and increased arousal and dissociation.

In addition at least four of the following criteria need to apply: intrusive thoughts, flashbacks or nightmares, avoiding situations that could trigger the memory (and possibly re-experiencing), hyper arousal (those three are the main criteria for PTSD), and negative alterations in mood and/or cognition, which frequently relate to negative expectations about the future and the world in general, feelings of guilt, and self-blame.

Prevalence data for PTSD vary widely between countries and populations. While for US-American adults from the general population lifetime prevalence is estimated at 7–12% (12), persons from regions with higher exposure to traumatic events (crisis regions, refugee camps, etc.) show occurrence rates of up to 58%, e.g., after combat exposure (23). The prevalence rates for deployed US military personnel may be as high as 14–16% [for review see (4)].

In Germany, the lifetime prevalence for PTSD is estimated at 1.5–2.3%. However, some estimate it at 6% for men and 10% for women (5). For the German military prevalence rates of 2.9% within 1 year following the return from deployment abroad were documented (6). Wittchen et al. (6) also estimate that only 50% of German soldiers with PTSD receive a diagnosis and treatment.

PTSD—Challenges in Treatment

There are several psychotherapeutic approaches in treating PTSD [for an overview see (7)], which frequently are accompanied by pharmacological treatment, mostly for comorbid disorders or specific symptoms as e.g., sleeping problems.

In addition to general psychotherapeutic methods, such as building a trustworthy connection between patient and therapist, a phase of stabilization usually takes place before trauma confrontation.

During the trauma confrontation, the patient is asked to mentally revisit the traumatic event (imaginal exposure) and reprocess it on several levels (cognition, emotion, physiological reactions). This is usually stressful for the patient and therefore requires a safe therapeutic environment.

The following challenges are frequently encountered in therapies with patients with PTSD: distrust toward other humans and the world in general, which is perceived as dangerous and threatening; life is seen as uncontrollable; the patient feels worthless and weak; loss of enjoyment.

Many patients with PTSD therefore do not seek therapeutic help for a long time and this also poses a problem for family and friends. Social relationships are frequently broken off, leaving the patient without a supportive social network. Also, these symptoms make it more difficult to establish the necessary trustful therapeutic alliance, the basis of a successful therapy.

Evidence based psychotherapeutic approaches can effectively reduce symptoms of PTSD in veterans. For example, in a study by Monson et al. (8), 40% of veterans showed no PTSD symptoms anymore at the end of cognitive reprocessing therapy, and further 50% showed a significant reduction of symptoms.

However, these improvements were only stable for a short period of time. In a controlled study with German veterans with PDTS, EMDR therapy proved effective in reducing symptoms (9).

However, in their review, Steenkamp et al. (10) conclude that evidence-based therapy (cognitive-behavioral and trauma-focused) for PTSD is not as effective for veterans in comparison to other patient populations. One reason might be the difficult to establish therapeutic alliance and strong rejection of confronting the trauma. Steenkamp et al. (10) suggest that it is necessary to find alternative, additional approaches for the treatment of PTSD in soldiers.

Animal Assisted Interventions

One form of intervention which recently has been combined with standard treatments of PTSD are animal-assisted interventions [AAI; for review see (11)], usually with horses or dogs, also in the treatment of soldiers with PTSD (1214).

The International Association of Human Animal Interaction Organizations [(15), p. 5] defines AAI as a “goal oriented and structured intervention that intentionally includes or incorporates animals in health, education and human service (e.g., social work) for the purpose of therapeutic gains in humans. It involves people with knowledge of the people and animals involved.” It also distinguishes between Animal Assisted Therapy (AAT) and Animal Assisted Activities (AAA). While in AAT at least one person providing the AAI needs to be a trained therapist (either the animal handler or a person supervising the intervention), this is not required for AAA, which however still requires a certain level of training and expertise from the human-animal team.

Human-Animal Interactions (HAI)—Effects Relevant for Trauma and PTSD

Research on the effects of interactions between humans and animals in general and in animal-assisted interventions provides a rationale for AAI supporting trauma therapy for soldiers with PTSD. The following effects of human-animal interaction (HAI), either assessed within the frame of AAI, experiments, or animal ownership, might be helpful in the treatment of patients with PTSD [for review and references not otherwise specified see (16)].

Well documented are the social effects of HAI. Humans of all ages, with and without clinical disorders, communicate more and more positively, verbally and non-verbally, in the presence of friendly animals. This is called the “social catalyst effect” of animals. Persons accompanied by a friendly looking animal receive more positive attention from others also, people in the company of animals (dogs) are trusted more by others. All these social effects of HAI could be important for therapy for soldiers with PTSD, because an animal involvement could facilitate establishing the necessary therapeutic alliance between therapist and client.

Among the psychological effects of HAI are an increase of the person’s concentration and motivation in completing different tasks (1719). Animal contact can reduce depression, anxiety, aggression and promote a positive mood and a sense of calmness, particularly before and during stress eliciting situations, including psychotherapeutic and medical treatments or exams. For patients with PTSD, who are usually anxious about confronting their trauma, these effects of HAI could be very helpful.

This reduction of psychological stress is also mirrored in the physiological effects: HAI has been shown to buffer human stress reactions, of the hypothalamic-pituitary-adrenal system (HPA-axis), as well as of the autonomic nervous system (ANS). Cortisol levels and cardiovascular parameters (heart rate and blood pressure) are positively influenced by HAI, with largest effects being found for stressful situations. The physical contact between the human and the animal seems to be especially effective, and also the level of familiarity with the animal, or the closeness of the relationship seems to be important, e.g., in increasing the level of the hormone oxytocin and the neurotransmitter dopamine.

Processes Underlying the Positive Effects of AAI

The many different effects of HAI cannot be explained by one single theory. Their explanation requires a set of theories and processes, which are linked to each other [for review see (20)]. Some of these processes, which seem most important for the treatment of PTSD, will be briefly introduced here [for a more detailed report, see (2021)].

Julius et al. (22) describe the phenomenon that the mere presence of friendly, calm and resting animals can reduce psychological and physiological stress reactions and promote a feeling of security and a safe surrounding, which they call “biophilia effect.” This is probably due to subconscious perception of calm animals as a cue for a safe surrounding, based on biophilia (23). During the evolutionary history humans always lived together with animals in their surrounding and paying attention to them contributed to the survival of humans and promoted their fitness. This attention, or more general the affinity to animals and nature in general, is called biophilia (23).

Animals can contribute to human relaxation, not only via the biophilia effect, which requires no direct contact, but also via the activation of the oxytocin system, primarily via physical contact between human and animal. This seems to be a neurobiological mechanism which can explain many of the positive social, psychological and physiological effects of HAI (1622), since there is a large overlap between the effect spectrum of HAI and of oxytocin.

The hormone and neurotransmitter oxytocin, which is also known as the attachment hormone, promotes social interaction and communication, mental and physiological relaxation, trust, a good mood, and reduces stress parameters (HPA axis and ANS) like blood pressure, heart rate and cortisol levels, and aggression.

Its release is stimulated by e.g., massage, breastfeeding, but also other physiological stimulation like pleasant physical contact in general and touch (162425). Research documented that persons petting a friendly dog show an increase in their oxytocin level and this effect is even larger if human and animal have a close relationship (2628).

The activation of the oxytocin system seems to be a key for the explanation of additional positive effects of AAI supporting standard trauma therapy in a human-only setting. In AAI, nearly all patients want to pet the animals and therapy animals usually allow this kind of physical closeness and might even enjoy it.

Even though this has not yet been investigated for patients with PTSD, it can be assumed from existing research documenting positive effects of AAI (11) that the activation of the oxytocin system might also occur in persons with this clinical disorder. While physical contact between therapist and patient is to be avoided in psychotherapy, and thus the oxytocin system cannot be activated this way, physical contact is an immanent part of AAI (29). Therefore, patients might develop trust toward their therapist (or the persons included in the AAI) easier and quicker, show a better mood, communication, relaxation, and motivation during sessions.

These aspects are particularly important for trauma therapy, since patients are usually mistrusting, stressed and anxious. In addition, in AAI patients often show increased motivation, first to start a therapy at all, second, to attend the therapy sessions on a regular basis, and third, to more actively participate in the sessions.

Wohlfarth et al. (18) describe the activation of intrinsic motivation via animal involvement, and propose that animals represent stimuli activating intrinsic motivation for most humans, probably also due to biophilia. Therefore, activities involving animals a person likes are carried out with more emotional involvement and energy.

Further processes which might be based at least partly on biophilia and the attention humans pay to animals, involve distraction (30), e.g., from the symptoms and negative thoughts, and mindfulness, meaning keeping one’s attention in the here and now, not ruminating about the past or a negative future.

Interactions with animals today are frequently found in psychotherapeutic treatments including mindfulness trainings, also for patients with PTSD who profit from such trainings since they might help to reduce intrusions and flashbacks. Traditional mindfulness trainings, however, are often difficult for patients with PTSD due to social anxiety in a group setting and the sleeping problems, which in turn cause concentration problems.

Interventions Involving Dogs for Veterans With PTSD

During the recent years, several studies and reviews [e.g., (31)] document a high potential of interactions with dogs for veterans with PTSD.

These interactions, however, have mostly been investigated empirically in veterans living with either companion dogs or a (psychiatric) service/assistance dog. Stern et al. (32) investigated 30 US military veterans with PTSD who lived with a dog. Self-reported positive effects, assessed retrospectively, included an increase in calmness and a decrease in loneliness, depression and worries about one’s own and the family’s safety.

O’Haire and Rodruigez (33) report on the effects of service dogs as complementary treatment for PTSD in military personnel and veterans. In contrast to a group receiving usual care, the intervention group had improved in symptoms of PTSD after receiving a service dog, specifically higher quality of life, less depression and better social functioning.

Rodruigez et al. (34) also found positive effects of living with a service dog on anger, anxiety, sleep disturbance and alcohol abuse in a population of veterans with PTSD, in contrast to veterans with PTSD on the waiting list for a service dog. Those veterans living with a service dog also displayed a higher cortisol awakening response, which the authors interpreted as a sign for better health and well-being in this population.

Owen et al. (35) describe canine-assisted therapy as a useful complementary or alternative medicine adjunct treatment for veterans with PTSD, based on a biopsychosocial rationale. Similarly, Yount et al. (36) argue that interactions with dogs may benefit veterans with PTSD in their treatment, based on neurobiological mechanisms, mainly the increase of oxytocin levels via contact with dogs.

However, no detailed description of such complementary adjunct dog-assisted interventions have been published, nor have they been evaluated. Therefore, our pilot project was aimed at both developing and implementing such a dog-assisted intervention and providing some empirical evidence. Another special feature of our project is the involvement of military service dogs and their handlers in delivering the dog-assisted intervention, in addition to the standard psychiatric treatment for veterans with PTSD.

University of Sydney
Media Contacts:
Ivy Shih – University of Sydney
Image Source:
The image is in the public domain.

Original Research: Open access
“Companion dog acquisition and mental well-being: a community-based three-arm controlled study”. Lauren Powell, Kate M. Edwards, Paul McGreevy, Adrian Bauman, Anthony Podberscek, Brendon Neilly, Catherine Sherrington & Emmanuel Stamatakis.
BMC Public Health doi:10.1186/s12889-019-7770-5.


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