Abstract

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.^3,4 Other, 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,^5,7 although this is not always the case.^2,8 Nonetheless, 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

Results

Main findings

About 46% of the sample reported that they had a dog at home. 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 Box shows 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

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.⁹ From this level of change in dog walking, and assuming a population-attributable risk of 18% for physical inactivity and coronary heart disease (CHD),¹³ it can be estimated that the maximal DAF_{cardiovascular} 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.¹³ A 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".¹³ Thus, 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.¹⁵ This is clearly an overestimate for the risks of dog walking, as only a quarter of dog bites occur in open space, roads or paths.¹⁶ However, 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

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,¹⁸ dog 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

References

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Authors' details

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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