The notion that companion animal ownership (CAO) can reduce loneliness and improve mental health outcomes is not a new one. Companion animal (CA) owners have long perceived their CAs make them happier and healthier (Animal Medicines Australia, 2019). This belief was reinforced during the COVID-19 pandemic as CA researchers and medical professionals released opinion pieces publicising the ‘benefits’ of CAO for mental health (Geppert, 2020; Heotis, 2021), and people bought and adopted CAs at increased rates to cope with pandemic lockdowns (Morgan et al., 2020; Roy, 2020). Qualitative research conducted during the pandemic reflects this positive public sentiment (Roe et al., 2023; Shoesmith et al., 2021; Zablan et al., 2022), but quantitative findings have largely disputed the ‘feel-good’ story of CAO and pandemic wellbeing.
Quantitative CA COVID-19 studies comparing the loneliness, mental health, and wellbeing of CA owners and non-CA owners reported a non-significant effect of CAO (Clements et al., 2021; Denis-Robichaud et al., 2022; Grajfoner et al., 2021), or negative effect of CAO (Amiot et al., 2022; Law et al., 2022; Mueller et al., 2021), on these outcomes. Although only a small number of studies reported CAO being associated with better loneliness, mental health, or wellbeing (Bohn et al., 2021; Giansanti et al., 2022; Ratschen et al., 2020; Tan et al., 2021), these positive findings were over-represented in media articles during the pandemic, providing a biased view of the CAO COVID-19 literature (Carver, 2020; National Geographic, 2021). Taken as a whole, the body of literature instead indicates CAO did not significantly reduce loneliness and improve mental health during the COVID-19 pandemic.
Dog Ownership, Physical Activity, Loneliness, and Mental Health
Human-animal interactions (HAI) researchers have proposed explanations for the ‘pet effect paradox’ (Herzog, 2022), where qualitative evidence provides compelling support for CAO when sampling CA owners, but quantitative evidence indicates no significant relationship between CAO and mental health. One possible explanation is that merely comparing CA owners and non-owners does not account for CA-related variables possibly influencing the relationship between CAO and mental health, such as the type of CA owned, or whether a CA promotes increased physical activity (Hughes et al., 2020). The CAO COVID-19 evidence suggests CA type and physical activity may be meaningful explanatory variables when considering the relationship between CAO and mental health (Bohn et al., 2021; Tan et al., 2021). Two of the studies reporting a positive association between CAO and mental health outcomes included physical activity as a variable of interest (Bohn et al., 2021; Tan et al., 2021). Bohn and colleagues (2021) found dog ownership and physical activity to be independently associated with lower depression during lockdown, while cat and bird ownership was not significantly associated with depression, demonstrating mixed results across CA types. Tan and colleagues (2021) investigated CAO and physical activity during lockdown in Singapore, finding CA owners reported higher mild-intensity physical activity and emotional wellbeing than non-owners. These findings suggest that CA type and physical activity may be unexpectantly impacting CAO comparison studies.
Reviewing the proposed theories of HAI also provides guidance as to which individual differences could explain why the effect of CAO on loneliness and mental health outcomes varies. These theories of HAI attempt to explain how CAO may improve human mental health, including the companionship (O’Haire, 2010), stress reduction (Friedmann et al., 1980), attachment and oxytocin (Beetz et al., 2012), social catalyst (Wood et al., 2015), exposure to green spaces (Zijlema et al., 2019), and physical activity theories (Dall et al., 2017).
Dog ownership has been a focus of HAI research due to the unique care dogs require. The exercise requirements of dogs far exceed those of other common CA types typically kept in the home, including cats, fish, birds, small mammals, and reptiles (Corridan, 2009). Dogs usually require exercise outside the home, not only for their physical health, but also for mental stimulation (Corridan, 2009). A wealth of evidence suggests dog ownership results in increased recreational walking and increased overall physical activity for dog owners (Christian et al., 2013; Westgarth et al., 2019), and there is clear evidence indicating physical activity strongly predicts both physical and mental health (Anderson & Shivakumar, 2013).
Loneliness is a major contributor to poor mental health and longitudinal research has demonstrated loneliness as predicting the later development of depression (Green et al., 1992). Although loneliness can be conceptualised as an indicator of unmet social needs and a motivator to implement steps to increase social connection (Perlman & Peplau, 1984), during the COVID-19 pandemic, the ability to put these steps into action were significantly restricted by public health directives (Australian Institute of Health and Welfare [AIHW], 2021), resulting in increased depression and anxiety for global citizens during the pandemic (Robinson et al., 2022). Dog walking may benefit mental health and reduce loneliness via a social catalyst effect, as walking a dog increases the frequency of chance social interactions with strangers (McNicholas & Collis, 2000; Wood et al., 2015). During COVID-19 such chance ‘COVID-safe’ social encounters were at times the only social contact dog owners experienced (Zablan et al., 2022), and studies showed increased dog walking during COVID-19 resulted in reduced loneliness (Carr et al., 2021; Lee et al., 2022).
Dog walking may also expose owners to natural outdoor environments, or green spaces. Exposure to green spaces has been cited as a positive contributor to mental health, in addition to the benefits of physical activity (Van den Berg et al., 2015). The physical activity, social catalyst, and exposure to green spaces theories all provide indications dog ownership may predict reduced loneliness and improved mental health via dog walking.
Although the theoretical basis for relationships between dog ownership, physical activity, and mental health is strong, the research evidence is not so clear. This is, in part, because few studies investigate the two relationships of interest; whether dog ownership predicts increased physical activity, and whether this increased physical activity predicts mental health outcomes. Those that do, have reported mixed findings. Dunn and colleagues (2018) found dog ownership was associated with increased physical activity, but not depression or loneliness among cardiac patients. Conversely, studies conducted in Singapore suggested CA owners/caregivers engaged in more physical activity, and had higher scores on measures of emotional wellbeing, social functioning, and energy (Goh et al., 2020; Tan et al., 2021). Other studies investigated whether dog walking predicted mental health outcomes, but not whether dog ownership engaged in more physical activity or walking than non-dog ownership. Two of these studies found dog walking was associated with reduced loneliness (Carr et al., 2021; Lee et al., 2022), while one found no significant association between dog walking and loneliness (Qian Lau & Oliva, 2023). When considering depression outcomes, evidence was similarly mixed, with one study reporting no significant relationship between dog walking and depression (Cui et al., 2021), while one study found dog walking was associated with reduced depression (Lima et al., 2022). It is surprising, given the large research area of dog ownership and physical activity, that so few studies investigate dog ownership, physical activity, loneliness, and mental health outcomes together.
Older Adult Dog Ownership, Physical Activity, Loneliness and Mental Health
Older adult loneliness and mental health have been priorities of mental health research during COVID-19 (Legate et al., 2022; World Health Organisation, 2020). Research evidence suggests older adults did experience increased rates of loneliness (Su et al., 2022), depression (Briggs et al., 2021), and anxiety (Gosselin et al., 2022) during the pandemic, although people within other demographic groups, such as younger adults and women, appeared to experience similar or worse mental health outcomes (Bu et al., 2020; Li & Wang, 2020). Older adults have also been a particular focus of research investigating dog ownership and physical activity. Multiple studies have demonstrated older adult dog owners as engaging in significantly more walking than non-dog owners (Dall et al., 2017; Feng et al., 2014). It is possible the physical activity promoted by dog ownership is more beneficial for older adults, due to older adults engaging in less overall physical activity than younger adults (Chodzko-Zajko et al., 2009).
Our study will add to the literature by being the first to investigate dog ownership, CA-related physical activity such as dog walking, physical activity not conducted with a CA, and mental health outcomes together. This will provide insights into the types of physical activity associated with mental health outcomes, and whether physical activity conducted with or without a CA is more beneficial. Our study is also the first to investigate whether the relationships between dog ownership, physical activity, and mental ill health are stronger for older adults compared to younger adults.
Aims and Hypotheses
This study aimed to (1) investigate whether dog ownership, CA-related physical activity, and non-CA-related physical activity were meaningful explanatory variables for the relationships between CAO, depression, and anxiety via loneliness and (2) examine whether the relationships between these variables differed for older adult CA owners compared to younger adult CA owners.
The hypothesised relationships are displayed in Fig. 1. We hypothesised these relationships would be stronger for older adult CA owners compared to younger adult CA owners.