Author	Title	Year	Sample Size	Methods	Sample Population	Mental Health Measurement(s)	Findings	Article Quality Index Score (0–9)
Research with Positive Associations between Pet Ownership and Mental Health
Serpell, J. [43]	Beneficial effects of pet ownership on some aspects of human health and behaviour	1991	71	-Prospective -Quantitative	General	-GHQ-30	After acquiring a pet, dog-owners demonstrated significant improvement in their GHQ-30 scores during the first six months after acquiring a pet, and moderate at 10-month follow-up. Cat owners demonstrated small and non-statistically significant improvement at six months.	3
Budge, R.C. et al. [48]	Health correlates of compatibility and attachment in human-companion animal relationships	1998	176	-Cross-sectional -Quantitative	General	-AHCS -Pet Attachment Survey -ISEL -MHI	As compatibility in the human–pet relationship increased, so did the physical and mental health and wellbeing for the human. Human–pet compatibility was not associated with levels of social support.	5
Zimolag, U.; Krupa, T. [49]	Pet Ownership as a Meaningful Community Occupation for People With Serious Mental Illness	2009	59	-Cross-sectional -Quantitative	People receiving mental illness treatment	-GAF -EMAS -CIS-APP	Pet owners demonstrated better social community integration than non-pet owners. Pet owners may also engage in more meaningful activity and have higher psychological community integration than non-pet owners.	6
McConnell, A.R. et al. [50]	Friends with benefits: on the positive consequences of pet ownership	2011	217	Prospective, cross section -Quantitative	General	-CES-D -UCLA -RSES -SHS	Pets can serve as effective social resources for their owners and positive connections with pets are correlated with positive attachment styles, personality traits, and self-esteem generally and when facing social rejection.	4
Black, K. [51]	The Relationship Between Companion Animals and Loneliness Among Rural Adolescents	2012	293	-Cross-sectional -Quantitative	Adolescents	-ULS -CABS -SSQSR	Pet owning adolescents had significantly lower loneliness scores and there was an inverse relationship between level of bond with pet and levels of loneliness.	8
Stern, S.L. et al. [52]	Potential Benefits of Canine Companionship for Military Veterans with Posttraumatic Stress Disorder (PTSD)	2013	30	-Cross-sectional -Quantitative	Military Veterans	-BDI -LAPS -PCL	Since adopting their dog, veterans self-reported feeling calmer, less lonely, less depressed, and less worried about their and their family’s safety. Veterans did not report less PTSD symptomatology since adopting their dog.	6
Wright, H. et al. [53]	Pet Dogs Improve Family Functioning and Reduce Anxiety in Children with Autism Spectrum Disorder	2015	70	-Cross-sectional -Quantitative	Children with ASD and their families	-BFRS -SCAS	Family functioning improved and child anxiety decreased in the dog-owning group compared to the non-dog owning group.	6
Gadomski, A.M. et al. [54]	Pet Dogs and Children’s Health: Opportunities for Chronic Disease Prevention?	2015	643	-Cross-sectional -Quantitative	Children	-SCARED-5 -SDQ -PHQ-2	Having a pet dog in the home was associated with a decreased probability of childhood anxiety.	5
Lem, M.; Coe et al. [55]	The Protective Association between Pet Ownership and Depression among Street-involved Youth: A Cross-sectional Study	2016	190	-Cross-sectional -Quantitative	Children and adolescents	-CES-D	Pet ownership among street youth was associated with lower levels of depression.	7
Bos, E.H. et al. [29]	Preserving Subjective Wellbeing in the Face of Psychopathology: Buffering Effects of Personal Strengths and Resources	2016	2411	-Cross-sectional -Quantitative	General	-MANSA -HI -PWB -SPF-IL -DASS -QIDS -PANAS -HSQ -EQ	Owning a pet and/or having a partner protected study participants’ wellbeing even when psychological distress symptoms were present.	6
Hall, S.S. et al. [56]	The long-term benefits of dog ownership in families with children with autism	2016	37	-Longitudinal -Mixed	Children with ASD and their families	-PSI-SF -LAPS	Families of autistic children who had acquired a pet dog demonstrated improved family functioning and reduced parental stress in comparison to control group families who did not acquire a pet dog.	8
Marsa-Sambola, F. et al. [57]	Quality of life and adolescents’ communication with their significant others (mother, father, and best friend): the mediating effect of attachment to pets	2017	2262	-Cross-sectional -Quantitative	Adolescents	-KIDSCREEN-10 Index -SAPS	Higher attachment to pet dog/cat was associated with better quality of life. Attachment to pets may also enhance communication with parents and best friends.	6
Muldoon, A.L. et al. [58]	A Web-Based Study of Dog Ownership and Depression Among People Living With HIV	2017	199	-Cross-sectional -Quantitative	People with a physical illness	-CES-D10 -RRC-ARM -CYRM-28	Non-current dog ownership among research participants was significantly and positively associated with depression with non-current dog owners being three times more likely to report symptoms of depression compared with current dog owners.	8
Wu, C.S.T. et al. [59]	The Association of Pet Ownership and Attachment with Perceived Stress among Chinese Adults	2018	288	-Cross-sectional -Quantitative	General	-PSS -CABS	Higher levels of pet attachment are associated with lower levels of perceived stress among pet owners. Dog owners report being more attached to their pet than other types of pet owners.	7
Powell, L. et al. [60]	Companion dog acquisition and mental well-being: a community-based three-arm controlled study	2019	71	-Prospective -Quantitative	General	-ULS -PANAS -K-10	Acquiring a dog was associated with lower levels of loneliness at three-month and eight-month follow up.	6
Carr, E.C.J. et al. [61]	Evaluating the Relationship between Well-Being and Living with a Dog for People with Chronic Low Back Pain: A Feasibility Study	2019	56	-Cross-sectional -Mixed methods	People with a physical illness	-HRQOL -WHO-5 -PROMIS anxiety SF4 -PROMIS depression SF4 -ULS -SSNS -PROMIS Companionship scale -PROMIS Emotional support scale -LAPS -HAB	Dog owners reported fewer depression and anxiety symptoms over the last week before the survey than the non-dog owners.	5
Yolken, R. et al. [28]	Exposure to household pet cats and dogs in childhood and risk of subsequent diagnosis of schizophrenia or bipolar disorder	2019	1371	-Cross-sectional -Qualitative	People receiving mental illness treatment	N/A	Exposure to a pet dog during the first 12 years of life was associated with a decreased hazard of having a subsequent diagnosis of schizophrenia.	5
Research with Mixed Associations between Pet Ownership and Mental Health
Siegel, J.M. [62]	Stressful life events and use of physician services among the elderly: the moderating role of pet ownership	1990	938	-Prospective -Mixed	Elderly	-LNS -CES-D	Elderly respondents with stressful life events made fewer visits to the physician if they had a pet dog. The presence of a dog was not associated with lower levels of depression.	6
Gulick, E.E.; Krause-Parello, C. A. [63]	Factors related to type of companion pet owned by older women	2012	159	-Cross-sectional -Quantitative	Elderly (females)	-PGWB -ULS	Women with dogs reported higher general health, vitality, and total well-being but worse levels of depression than women with cats.	6
Fritz, C.L. et al. [64]	Companion animals and the psychological health of Alzheimer patients’ caregivers	1996	244	-Cross-sectional -Quantitative	Caregivers	-ZBI -LSI-Z -GDS -LAPS	Stress was less for pet owning younger male and female caregivers of cognitively impaired adults but not for older pet owning female caregivers.	5
Tower, R.B.; Nokota, M. [19]	Pet companionship and depression: results from a United States Internet sample	2006	2291	-Cross-sectional -Quantitative	General	-CES-D	Unmarried women who live with a pet had the fewest depressive symptoms and unmarried men who live with a pet had the most.	6
Wisdom, J.P.; Saedi, G.A.; Green, C.A. [38]	Another Breed of “Service” Animals: STARS Study Findings About Pet Ownership and Recovery From Serious Mental Illness	2009	177	Prospective -Longitudinal -Mixed Methods	People with serious mental illness	-CSI -W-QLI	Pet owners were more likely to have affective versus psychotic diagnosis, were more likely to have a comorbid substance abuse disorder and were more likely to live with someone. They also had fewer hospitalizations.	4
Cline, K.M.C. [65]	Psychological Effects of Dog Ownership: Role Strain, Role Enhancement, and Depression	2010	201	-Cross-sectional -Quantitative	General	-CES-D	Dog ownership had no direct impact on depression. Dog ownership was associated with greater wellbeing for women and those who are unmarried.	7
Ramirez, M.T.G.; Hernandez, R.L. [66]	Benefits of dog ownership: Comparative study of equivalent samples	2014	602	Prospective- Cross-Sectional -Quantitative (Snowball sampling)	General	-SWLS -SHS -PHQ -PSS -SFHS	Dog owners’ scores were significantly lower for psychosomatic symptoms and stress and were higher for better mental health, however, there were no differences between groups for happiness and life satisfaction.	5
Bradley, L.; Bennett, P.C. [22]	Companion-Animals’ Effectiveness in Managing Chronic Pain in Adult Community Members	2015	173	-Cross-sectional -Mixed methods	People with physical illness	-DASS-21	There was no relationship between companion animal ownership and stress or anxiety, however, owners had higher levels of depression than non-owners. Depression among those who perceived their animal as more friendly was lower and for those who perceived their animal as more disobedient stress was higher.	5
Girardi, A.; Pozzulo, J.D. [24]	Childhood Experiences with Family Pets and Internalizing Symptoms in Early Adulthood	2015	318	-Cross-sectional -Quantitative	General	-LAPS -CTQ -CEDV -STAI-T -BDI	Participants who were exposed to pet aggression in childhood and reported medium level bonds with animals also reported more depression and anxiety symptoms in early adulthood. Those who were not exposed to pet aggression reported fewer internalizing symptoms.	7
Bennett, P.C. et al. [67]	An Experience Sampling Approach to Investigating Associations between Pet Presence and Indicators of Psychological Wellbeing and Mood in Older Australians	2015	68	-Prospective Experience sampling over 7 days -Quantitative	Elderly	-DASS -SPS -ULS-R	There was not a difference between pet-owners and non-pet-owners in mental health outcomes, however, for pet owners, level of pet presence in daily activities was associated with better mental health outcomes.	6
Branson, S.M. et al [68].	Depression, loneliness, and pet attachment in homebound older adult cat and dog owners	2017	39	-Cross-sectional -Quantitative	Elderly	-GDS-SF -ULS-R	Cat owners reported fewer depressive symptoms than dog owners, especially for men, but the differences in levels of depressive symptoms between dog and cat owners was small.	6
Mueller, M.K. et al. [69]	Human-animal interaction as a social determinant of health: descriptive findings from the health and retirement study	2018	1657	-Retrospective -Cross-sectional -Quantitative	Elderly	- Created measures	Pet ownership was positively correlated with reporting depression in lifetime, however, there was no difference in self-reported depression in the last week between pet owners and non-owners.	6
Carr, D.C. et al. [70]	Typologies of older adult companion animal owners and non-owners: moving beyond the dichotomy	2019	1179	-Cross-sectional -Quantitative Data was collected from the Health a Retirement Study	Elderly	-CES-D -BFI	Five clusters of owners and four clusters of non-owners were identified with varying mental health outcomes. Pet owners were higher in neuroticism and lower in extraversion.	5
Liu, S.X. et al. [30]	Is Dog Ownership Associated with Mental Health? A Population Study of 68,362 Adults Living in England	2019	68,362	-Repeated cross-sectional survey running in annual thematic cycles -Quantitative	General	-GHQ-12	Single dog owners were more likely to demonstrate higher levels of short-term psychological distress. Dog owners with partners had lower levels of self-reported mental illness.	7
Ingram, K.M.; Cohen-Filipic, J. [20]	Benefits, challenges, and needs of people living with cancer and their companion dogs: An exploratory study	2019	122	-Cross-sectional -Mixed methods	People with physical illness	-CES-D -FACT-G -LAPS	The human–pet bond was not directly linked with well-being. Depressive symptoms depended on cancer treatment status and level of bond with those having completed treatment and had a stronger bond reported fewer depressive symptoms. For continuing treatment stronger bonds was positively correlated with depression.	5
Min, K.D. et al. [71]	Owners’ Attitudes toward Their Companion Dogs Are Associated with the Owners’ Depression Symptoms-An Exploratory Study in South Korea	2019	654	-Cross-sectional -Quantitative	General	-CES-D	Those respondents who had a negative view of their pets also were more likely to report the presence of depression. Those who had a more positive view of their pet were less likely to report depression.	5
Hajek, A.; Konig, H.H. [23]	How do cat owners, dog owners and individuals without pets differ in terms of psychosocial outcomes among individuals in old age without a partner?	2020	1160	-Longitudinal -Cross-sectional -Quantitative	Elderly	-CES-D -De Jong Gierveld Loneliness Scale	Dog owners were less socially isolated than non-pet owners, however this was not true for cat owners. Pet-owning women also reported less loneliness, whereas loneliness did not differ between pet-owning and non-pet-owning men.	8
Teo, J.T.; Thomas, S. J. [72]	Psychological Mechanisms Predicting Wellbeing in Pet Owners: Rogers’ Core Conditions versus Bowlby’s Attachment	2019	298	-Cross-sectional -Quantitative	General	-DASS-21 -BSI -WHO QOLBREF -OPRQ -PAQ -BLRI	Pet owners and non-pet owners did not significantly differ in terms of QOL or psychopathology. However, in pet owners, secure pet attachments were associated with lower psychological distress and psychopathology. Differences in wellbeing is related to qualities of individual human–pet relationships.	7
Endo, K. et al. [73]	Dog and Cat Ownership Predicts Adolescents’ Mental Well-Being: A Population-Based Longitudinal Study	2020	2584	-Prospective cohort study -Quantitative and qualitative	Adolescents	-WHO-5	Dog ownership at age 10 predicted better well-being at age 12 compared to no dog ownership. Cat ownership at age 10 predicted worse well-being at age 12 compared to no cat ownership.	4
Research with Negative Associations between Pet Ownership and Mental Health
Parslow, R.A. et al. [74]	Pet ownership and health in older adults: Findings from a survey of 2551 community-based Australians aged 60–64	2005	2551	-Cross-sectional -Quantitative	Elderly	-SF-12 -GADS -PANAS -EPQ-R	Those with pets have poorer mental and physical health and use more pain relief medication than those without pets. Further, our study suggests that those with pets are less conforming to social norms as indicated by their higher levels of psychoticism.	6
Mullersdorf, M. et al. [40]	Aspects of health, physical/leisure activities, work and socio-demographics associated with pet ownership in Sweden	2010	39,995	Retrospective- Cross-sectional -Quantitative	General	-Aspects of health and mental health on a five-point Likert scale	“Pet owners in this study reported poorer mental health than non-pet owners. However, the authors suggest that the increase in depression or feelings of loneliness might predispose people to buying a pet.”	7
Antonacopoulos, N.M.D.; Pychyl, T.A. [13]	An Examination of the Potential Role of Pet Ownership, Human Social Support and Pet Attachment in the Psychological Health of Individuals Living Alone	2010	132	-Cross-sectional -Mixed Methods	General (adults living alone)	-MSPSS -LAPS -CES-D -ULS	“High attachment to pets predicted significantly higher scores on loneliness and depression. Our findings emphasize the complexity of the relationship between pet ownership and psychological health and suggest that pet ownership may not be beneficial for the psychological health of all individuals living alone.”	7
Peacock, J. et al. [12]	Mental health implications of human attachment to companion animals	2012	150	-Cross-sectional -Quantitative	General	-BSI-18 -MDSS -CEN SHARE PAS -OPRQ	“Human–animal relationships are associated with increased reports of psychological symptomatology. This study adds to the body of evidence that suggests that to understand human-animal relationships and their impact on well-being, it is pivotal to assess what the relationship symbolizes for an individual.”	6
Sharpley, C.et al. [75]	Pet ownership and symptoms of depression: A prospective study of older adults	2019	5334	-Longitudinal -Cross-sectional -Quantitative	Elderly	-CES-D	“In conclusion, the present results indicate that an increase in depressive symptoms is associated with higher odds of dog ownership in community-dwelling older people, but provide no evidence of a protective effect of pet ownership on changes in depressive symptoms over time.”	6
Research with No Associations between Pet Ownership and Mental Health
Raina, P. et al. [76]	Influence of companion animals on the physical and psychological health of older people: an analysis of a one-year longitudinal study	1999	995	-Longitudinal -Cross-Sectional	Elderly	-LAPS -Reported levels of satisfaction regarding mental health, happiness, and relationships	“No statistically significant direct association was observed between pet ownership and change in psychological wellbeing However, pet ownership significantly modified the relationship between social support and the change in psychological well-being over a 1-year period.”	4
El-Alayli, A. et al. [77]	Reigning cats and dogs: A pet-enhancement bias and its link to pet attachment, pet-self similarity, self-enhancement, and well-being	2006	70	Prospective -Quantitative	General	-PAS -CABS -SWLS -PANAS -SHS	“A secondary objective of this research was to examine whether psychological well-being was related to pet enhancement, pet attachment, and pet–self similarity. We found no evidence suggesting a linear relationship between pet attachment and psychological well-being.”	6
Wells, D.L. [78]	Associations between pet ownership and self-reported health status in people suffering from chronic fatigue syndrome	2009	193	Cross-sectional	People with physical illness	-GHQ-12 -SF36	Overall, findings suggest no statistically significant association between pet ownership and self-reported health in people with CFS. Nonetheless, people suffering from this condition believe that their pets have the potential to enhance quality of life.	6
Nagasawa, M.; Ohta, M [79].	The influence of dog ownership in childhood on the sociality of elderly Japanese men	2010	220	-Cross-sectional -Quantitative	Elderly	-IKIGAI -ULS-R -JMS-SSS	The effect of dog ownership on the mental condition of an elderly Japanese male may or may not be related to the early childhood dog ownership.	6
Rijken, M.; Van Beek, S. [80]	About Cats and Dogs Reconsidering the Relationship Between Pet Ownership and Health Related Outcomes in Community-Dwelling Elderly	2011	1410	-Prospective -Cross-sectional -Quantitative	Elderly	-GHQ-12 -ULS	Associations between pet ownership and the frequency of social contacts or feelings of loneliness were not found. Having a dog increased the likelihood of being healthy/active, whereas having a cat showed the opposite.	8
Ramirez, M.T.G., et al. [66]	Benefits of dog ownership: Comparative study of equivalent samples	2014	602	-Prospective survey -Quantitative	general	-SWLS -SHS -PHQ -PSS -SF-36	Dog owners had lower stress than non-dog owners, but there was no difference in overall mental health or happiness.	5
Enmarker, I. et al. [81]	Depression in older cat and dog owners: the Nord-Trondelag Health Study (HUNT)-3	2015	12,093	-Cross-sectional -Mixed methods	Elderly	-HADS-d	When comparing pet owners and non-pet owners, self-reported symptoms of depression in older women do not change based on ownership.	7
Bao, K.J.; Schreer, G. [82]	Pets and Happiness: Examining the Association between Pet Ownership and Wellbeing	2016	262	-Cross-sectional -Quantitative	general	-SHS -SWLS -mDES -ERQ -BMPN -BFI	Participants who owned pets and those who did not own pets did not appear to be very different in terms of wellbeing, personality, happiness, positive emotions, or negative emotions. Dog owners were happier than cat owners.	7
Miles, J.N.V. et al. [83]	A Propensity-Score-Weighted Population-Based Study of the Health Benefits of Dogs and Cats for Children	2017	5191	-Retrospective -Cross-sectional	Children	-GHQ-12 -SF-36	When variables related to child development were controlled for, there was no evidence of a positive impact of pet ownership on child mental health.	4
Batty, G.D. et al. [84]	Associations of pet ownership with biomarkers of ageing: population based cohort study	2017	8785	-Prospective -Quantitative	Elderly	-CES-D	There was no evidence of a clear association of any type of pet ownership with depressive symptoms	6
Dunn, S.L. et al. [85]	Dog Ownership and Dog Walking The Relationship With Exercise, Depression, and Hopelessness in Patients With lschemic Heart Disease	2018	122	-Prospective -Quantitative	Physical illness	-PHQ-9 -STHS	No differences in levels of hopelessness between the groups. Dog owners were more depressed until adjusting for age and sex, then no significant differences between dog owners and non-dog owners.	8
Zijlema, W.L. et al. [86]	Dog ownership, the natural outdoor environment and health: a cross-sectional study	2019	3586	-Cross-sectional -Quantitative	General	-SF-36	There was no indication for an association between dog ownership and mental health in groups with high or low access to natural outdoor environment (NOE) and with high or low residential surrounding greenness on the whole.	6
Branson, S.M. et al. [87]	Biopsychosocial Factors and Cognitive Function in Cat Ownership and Attachment in Community-dwelling Older Adults	2019	96	-Cross-sectional -Quantitative	Elderly	-LAPS -PSS -ULS -GDS-SF -Stress Salivary Biomarker	No associations with the biopsychosocial and cognitive measures. No link between the level of pet attachment and loneliness and depression.	7