The epidemiology of dog walking: an unmet need for human and canine health
 

Abstract

Objective: To describe the prevalence of dog walking in New South Wales, and to identify potential health gains if more dogs were walked.
Design: Cross-sectional analytical survey.
Setting and participants: 894 adults in NSW in 1998 (among the owners of approximately two million domestic dogs in NSW who were potential participants in dog-walking behaviours).
Interventions: None yet.
Main outcome measures: Dog walking hours per week; other DogEpi concepts to illustrate the public health gains include the DAF (dog attributable fraction), and the BBR (benefits to bites ratio).
Results: The response rate to the survey was 74%. 46% of households in NSW had a dog and, overall, dog owners walked 18 minutes per week more than non-dog owners. However, more than half of dog owners did not walk their dogs, and were less likely than non-owners to meet recommended levels of physical activity sufficient for health benefits. If all dog owners walked their dogs, substantial disease prevention and healthcare cost savings of $175 million per year might accrue.
Conclusions: There are potential benefits of dog walking for human health; currently, among dog owners, much of this benefit remains to be realised. There are also likely benefits for canine health. Dog walking should be promoted through national strategies recommending "Walkies for all by the year 2010".


About half of all homes in Australia have a pet, with dogs being the most prevalent, reported in about 40% of all households; these rates are similar to United States estimates for dog ownership.1,2Although most dogs are loved and well cared for by their owners, a key question is whether dogs might improve human health.

The notion that dogs might promote good health has been explored elsewhere, with studies of the psychological companionship and supportive role of dogs, and the use of "dogs as therapy" for older, institutionalised adults.3,4Other, small-scale studies have associated dog ownership with lower blood pressure, or even reduced re-infarction rates, among people with coronary heart disease.5,6

One area which has been less studied is the concept of dog walking, which provides physical activity for both dogs and people. Some surveys have proposed that people who own dogs are more active than those who do not,5,7although this is not always the case.2,8Nonetheless, this area has received much less attention than other pet-related research. This article focuses on the epidemiology of dog walking, which generally has been ignawed by researchers, and eschewed by epidemiologists. Hence this report cuts to the bone and unleashes an incisive public health argument for increasing dog walking in Australia. The primary research question was whether dog owners were more active than non-dog owners. In addition, the potential benefits of increased dog walking were estimated, using innovative DogEpi concepts.


Methods

This study was based on two population-based physical activity surveys carried out in New South Wales in March and November 1998.9Respondents were adults, randomly sampled from the Electronic White Pages. Questions were asked about dog ownership, and the amount of time the respondent had spent walking his or her dog in the previous week. Standard physical activity questions about walking and moderate and vigorous physical activity in the previous week were also asked.10The study variables were total time engaged in dog walking, any walking and total physical activity. Respondents were considered to have achieved "recommended levels of physical activity" for health benefit (150 minutes of at least moderate activity a week), based on the US Surgeon General's report.11Analyses were carried out with SPSS,12and included bivariate comparisons of proportions and means, and adjusted odds ratios using forced-entry logistic regression models to adjust for possible confounders.


Results

Main findings

Of the 1208 adults approached, 894 (74%) responded. They were aged 25-64 years, with a mean age of 44.4 years (95% CI, 43.9-44.9 years). Almost half (45.6%) were male, 75% were married or had a partner, and 28% reported some tertiary education. Overall, 47.1% achieved the US Surgeon General's recommended 150 minutes of total physical activity per week, and 27% achieved this only through walking.

About 46% of the sample reported that they had a dog athome. Among dog owners, the mean reported time allocated specifically for dog walking each week was 0.95 hours (95% CI, 0.77-1.13 hours per week), which was less than half of the average of two hours in total from all types of walking reported by dog owners each week (see Box). Among dog owners, 59% reported no dog walking, 26% reported up to 2.5 hours per week, and 15% reported at least 2.5 hours per week.

The Boxshows the mean time spent in physical activity according to dog ownership status. Those who owned dogs walked only 0.3 hours (about 18 minutes) more per week than non dog-owners. However, those who owned dogs and walked them less than one hour per week walked less, in total, than non dog owners (P = 0.01). Only those who walked their dogs for more than an hour per week walked significantly more or were significantly more active in total than non dog-owners. Further, the median number of walking sessions per week was 3.0 for both dog owners and non-owners (P = 0.98).

All dog-walker categories were slightly less likely to reach the 150 minute per week "health-enhancing" threshold, except for those who walked their dogs for 2.5 hours. For overall physical activity, similar proportions of owners and non-owners achieved 150 minutes of total activity per week (46.9% and 47.3%, respectively), and dog owners who did not walk their dogs were significantly less likely to meet the guidelines. Only those who walked their dogs for at least an hour a week were more likely (odds ratio, 1.89) than non-owners to achieve sufficient physical activity for health benefits (Box).

Further interpretation using DogEpi concepts

This section describes innovative interspecies epidemiological approaches to understanding the data. DogEpi concepts are not meant to hound researchers, nor meant to be a golden (standard) retriever of epidemiological wisdom, but they are descended from the litter of current epidemiological thought, some of which is scatological.

Firstly, the notion of dog walking to total walking ratio (DWTWR) and dog walking to total physical activity ratio (DWTPAR). The DWTWR, which is the percentage of all walking that was dog walking, was 22.9%. For 12% of the population, dog walking was half of their total walking. As a percentage of all physical activity, the DWTPAR was 13%, with 9% of the population doing at least half their total activity as dog walking.

More important is the DAF (dog attributable fraction), which is an epidemiological estimate of the proportion of disease which might be prevented if all of the dog owners walked their dogs for at least 150 minutes per week. If this occurred, the population prevalence of sufficient physical activity would increase from 47% to 71%. Such an increase in physical activity would be about 5-10 times as great as most population-level interventions designed to promote activity.9From this level of change in dog walking, and assuming a population-attributable risk of 18% for physical inactivity and coronary heart disease (CHD),13it can be estimated that the maximal DAFcardiovascular is about 9% of the total burden of CHD. Other estimates of the DAF for diabetes and colon cancer, along with other health benefits of being active, including reduced doctor visits and medication costs, could be estimated in addition to this cardiovascular DAF.

Direct healthcare cost savings can be estimated for specific increases in physical activity levels.13A conservative estimate suggested that A$36 million might be saved annually for coronary heart disease for every 5% increase in the prevalence of adults who are "sufficiently active".13Thus, if all dog owners walked their dogs more, this would be a 24% increase, resulting in direct healthcare cost savings of around $175 million per year. These savings would accrue rapidly, as cardiovascular risk reduction occurs sooner following the initiation of physical activity than after smoking cessation or dietary change.14

Nonetheless, it is important to calculate the other benefits and also the potential adverse effects and costs of keeping dogs as pets in Australia. The benefits of mental health improvement and stress reduction may be considerable, but are not used here in order to provide a conservative estimate of overall dog benefit. The adverse effects include the risks of zoonoses, but these are low. One public health issue is dog bites, which are estimated to cost $1.5 million in Victoria in direct healthcare costs.15This is clearly an overestimate for the risks of dog walking, as only a quarter of dog bites occur in open space, roads or paths.16However, we can use this overestimate to calculate a preliminary population health benefits to bites ratio (BBR) for the increased risk of dog bites and the risk reduction for heart disease to estmate the potential benefits versus risks of dog walking. We find that, even if only half of dog owners increased their dog walking to 150 minutes per week, then the resulting national savings of $87.5 million, divided by national dog bite costs of around $7 million, would give a very favourable cost benefit to bites ratio.


Discussion

In general, dog owners are not more active than non-owners, unless they practise regular, sustained dog walking. This article identifies the human health benefits of dog walking, and points to the need to encourage those with dogs to walk them more. It is possible that adults in the household other than the survey respondent also contributed to the time dogs are walked, so, from the canine perspective, our data could be an underestimate. Nonetheless, it would be a useful health-promotion strategy for inactive non-dog owners to acquire a dog in order to initiate regular moderate walking. There are reciprocal benefits for canine health -- from the dog's perspective, the amount walked is generally "never enough". This may be one way in which dog and human health might be improved, providing a biologically plausible explanation for the xeno-transmission of mortality gradients shared between pets and their owners, and described recently in the British Medical Journal.17

Dog walking is an important potential benefit of dog ownership. As about half of adult Australians are physically inactive, and the public health benefits of being active are comparable to those of smoking cessation,18dog walking should become widely recommended by human and canine health advocates alike. We should paws then, put our best feet forward, and take "man's best friend" for a walk more often. We advocate a campaign to promote "Walkies for all by the year 2010".



Acknowledgements

We thank NSW Health for data collection.



Competing interests

None declared.


References

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  2. Headey B. Health benefits and health cost savings due to pets: preliminary estimates from an Australian national survey. Soc Indicat Res 1999; 47: 233-243.
  3. Robb S, Stegman CE. Companion animals and elderly people — a challenge for the evaluation of social support. Gerontologist 1983; 23: 277-282.
  4. Francis GM, Turner J, Johnson S. Domestic animal visitation as therapy with adult home residents. Int J Nurs Stud 1985; 22: 201-206.
  5. Anderson WP, Reid CM, Jennings GL. Pet ownership and risk factors for cardiovascular disease. Med J. Aust 1992; 157: 298-301.
  6. Friedmann E, Thomas SA. Pet ownership, social support and one year survival after acute myocardial infarction in the Cardiac Arrhythmia Suppression Trial (CAST). Am J Cardiol 1995; 76: 1213-1217.
  7. Serpell J. Beneficial effects of pet ownership on some aspects of human health and behaviour. J Roy Soc Med 1991; 84: 717-720.
  8. Simons LA, McCallum J, Simons J. Pet ownership and future health. Med J Aust 1997; 167: 231-232.
  9. Bauman AE, Bellew B, Owen N, Vita P. Impact of an Australian mass media campaign targeting physical activity in 1998. Am J Prevent Med 2001; 21: 41-47.
  10. Armstrong T, Bauman A, Davies J. Physical activity patterns of Australian adults (AIHW Catalogue No. CVD 10). Canberra: Australian Institute of Health and Welfare, 2000.
  11. US Department of Health and Human Services. Physical activity and health: a report of the Surgeon General. Washington DC: Department of Health and Human Services, Centers for Disease Control and Prevention, 1996.
  12. Statistical package for the social sciences [computer program]. Version 10. Chicago, Ill.: SPSS Inc, 2000.
  13. Stephenson J, Bauman A, Armstrong T, et al. The costs of illness attributable to physical inactivity. Canberra: Commonwealth Department of Health, 2000.
  14. Blair SN, Kohl HW III, Barlow CE, et al. Changes in physical fitness and all cause mortality: a prospective study of healthy and unhealthy men. JAMA 1995; 273: 1093-1098.
  15. Watson W, Ozanne-Smith J. The cost of injury to Victoria. Report No. 124. Melbourne: Monash University Accident Research Centre, 1997.
  16. Ashby K. Dog bites. Hazard no. 26. Victorian Injury Surveillance System. Melbourne: Monash University Accident Research Centre, 1996: 7-13.
  17. Moloo J, Waller JL, McKeown RE, et al. Xenotransmission of the socioeconomic gradient in health? A population based study. BMJ 1998; 317: 1686-1686.
  18. Mathers C, Vos T, Stevenson C. Burden of disease and injury in Australia. (AIHW Catalogue no. PHE 17). Canberra: Australian Institute of Health and Welfare, November 1999.

(Received 15 Oct, accepted 2 Nov, 2001)



Authors' details

School of Public Health and Community Medicine, University of NSW, Sydney, NSW.
Adrian E Bauman, PhD, FAFPHM, Professor of Public Health;
Susan E Furber, PhD, Senior Lecturer.

Strathfield, NSW.
Schroeder J Russell, Canine Walking Advocate.

School of Population Health, University of Queensland, Herston, QLD.
Annette J Dobson, PhD, Professor of Biostatistics.

Reprints: Professor A E Bauman, Epidemiology Unit, Hugh Jardine Building, Locked Mail Bag 7017, Liverpool BC 1871, NSW.

©MJA 2001
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Cartoon
 
Walking and total physical activity time, and percentages meeting recommended physical activity levels, according to dog ownership and dog-walking status
             
    Total hours

Achieved 150 minutes per week

 
Category Number Walked
per week
(mean [95% CI])

Physical activity
per week
(mean [95% CI])

By walking
only
By total physical activity Adjusted odds ratio†(95% CI)

Non-dog owner 484 1.7 (1.4-1.8) 3.3 (2.9-3.6) 121 (25.1%) 229 (47.3%) 1.0 (reference)
Dog owner* 410 2.0 (1.8-2.2) 3.5 (3.1-3.8) 105 (29.7%) 191 (46.9%) 0.95 (0.72-1.23)
  Does not walk dog
  Walks dog up to 1 h/week
  Walks dog 1-2.5 h/week
  Walks dog > 2.5 h/week
240
33
73
61
1.3 (1.0-1.5)
1.3 (0.9-1.7)
2.2 (1.8-2.5)
5.0 (4.3-5.6)
2.5 (2.0-3.0)
1.9 (1.3-2.5)
4.1 (3.4- 4.8)
7.0 (6.0-8.1)
39 (16.3%)
5 (15.2%)
16 (21.9%)
45 (100%)
76 (31.7%)
9 (27.3%)
45 (61.6%)
61 (100%)
0.55 (0.39-0.77)
0.45 (0.2-1.01)
1.89 (1.1-3.1)
n/a

* Data on dog-walking time were missing for three dog owners.
† Odds ratios for meeting the recommended physical activity guidelines, adjusted for age, sex, education, marital status.
n/a = not available.