Studies show that family members share as much or more of the composition of their
microbiota (the trillions of micro-organisms in our guts) with their dogs as they do with
each other (Song et. al. 2013). This shows that the introduction of dogs into home
environments has a profound impact on the human microbiota. Additionally, many studies show
that children raised with dogs are less likely than others to develop a range of
immune-mediated disorders, including asthma and allergies (Ownby, Johnson, and Peterson
2002; Almqvist et al. 2003; Havstad et al. 2011). This suggests that dogs can serve as
probiotics for children by appropriately training their immune systems not to produce
inflammation in response to harmless stimuli. What is not known, however, is whether the
same is true for elderly populations and dogs. Thus, this study seeks to explore whether
dogs might also improve the physical and mental health of elderly adults by improving the
structure and function of their microbiota. The investigators propose a pilot/proof of
concept study to investigate whether dogs might improve the physical and mental health of
elderly adults via changing (improving) the structure and function of their microbiota (gut
flora). The investigators propose a pre-post study design that among 20 elderly individuals
(aged 50 and older) to investigate the probiotic effect that dogs might have on these
individuals. The investigators are particularly interested to know whether introducing a dog
into a home where one has not lived in the recent past increases the "positive"
microorganisms in the guts of the humans living with them. The investigators will also
measure the changes in markers of inflammation (from blood samples) as well as the changes
in self-reported scores of depression, frailty, physical activity, and general health and
well-being mobility among human participants. In order to assess any effects in the animal
study participants, the investigators will also collect and analyze fecal and blood samples
as well as conduct home visits to observe canine and human interactions and bonding and
conduct assessments of canine well-being using questionnaires/observational techniques that
have been validated for these purposes in other studies. Additionally, the investigators
will assess the interactions between of the participants with the dog and how having a dog
in the home may influence an individual's relationship with the dog and his/her thoughts
about the microbiota, human and canine health and human-animal interactions through monthly
The investigators have previously received IACUC approval for this study, approval number
One of the most amazing scientific discoveries of the last decade has been the important
roles that the trillions of micro-organisms in our guts (called the "microbiota") play in
promoting good physical health and emotional well-being. Unfortunately, many aspects of the
modern world conspire to alter the composition and function of the gut microbiota in ways
that damage health, especially in the elderly where strong correlations have been seen
between microbiota composition and frailty. Work from our research group and others suggests
that one very important factor that damages the microbiota in the modern world is our
separation from many micro-organisms with which the investigators co-evolved and which have
the ability to lower the types of chronic inflammation that are ubiquitous in the modern
world and that contribute to the development of most of our most pressing health issues,
from diabetes and heart disease to depression and dementia (Huang et al., 2013; Mayer et al,
2014; Naseribafrouei, 2013). While much has been written about the positive psycho-social
impacts that animal-human relationships have on human psychological health (Allen et al,
1991; Allen et al.; 2002; Collins et al, 2006; Kwong & Bartholomew, 2011; Kurdek, 2008;
Wells, 2007), less is known about the direct physical effects that animals have on human
health. What is known, however, is largely related to animals' effects on stress reduction
(Allen et al, 1991; Allen et al., 2002) anxiety (Foster & McVey Neufeld, 2013), mood
(Collins et al, 2006) and cardiovascular disease (Allen et al., 2002) What has been largely
unexplored, however, is the mechanism by which these interactions and positive impacts on
human health are taking place. Thus, working with colleagues who are world leaders in
studying links between the microbiota and health, the investigators propose to conduct a
study designed to explore the potential of dogs to serve as "probiotic delivery systems" to
enhance the physical health and cognitive and emotional functioning of at-risk elderly
The rationale for this novel approach to enhancing health and well-being in the elderly
comes from several lines of evidence. First, one recent study shows that family members
share as much or more of the composition of their microbiota with their dogs as they do with
each other (Song et al. 2013). This shows that the introduction of dogs into home
environments has a profound impact on the human microbiota. Second, many studies show that
children raised with dogs are less likely than others to develop a range of immune-mediated
disorders, including asthma and allergies (Ownby et al. 2002; Almqvist et al. 2003; Havstad
et al. 2011). This suggests that dogs can serve as probiotics for children by appropriately
training their immune systems not to produce inflammation in response to harmless stimuli.
Thus, what is not known, and what this study is designed to explore, is whether dogs might
also improve the physical and mental health of elderly adults by improving the structure and
function of their microbiota. This is a proof of concept / pilot study. Should results from
this study suggest that there is indeed a positive benefit/relationship to canine
companionship to the microbiota of elderly human companions, the investigators plan to
implement a larger, full-scale clinical trial to investigate this phenomenon.
Hypothesis: The investigators hypothesize that the introduction of a canine companion into
the home of an elderly individual (defined as aged 50 and older) will result in an increase
in protective or 'positive' gut micro-organisms and that this increase will correspond with
improved immune functioning in the elderly human study participants.
- Male or females aged 50 - 80.
- In general good health (mobile and able to care for a dog).
- Have not taken antibiotics in the last six months.
- Have not had a dog in the home for the past six months.
- Able to understand the nature of the study and able to provide written informed
consent prior to conduct of any study procedures.
- Able to communicate in English with study personnel.
- Willing to commit to fostering a dog for at least three months with the understanding
that at the end of the three months, they can keep the dog if they so desire.
- Individuals who are currently on any antibiotic therapy. Participants who are on an
antibiotic therapy will be allowed to participate in the study after a six month
- Unwilling to have a dog in the home for at least three months of time.
- Any of the following diagnoses, as identified by the intake evaluation conducted or
o History of any of the following mental illnesses: schizophrenia, bipolar I
disorder, drug or alcohol abuse active within 6 months of study entry. Determination
of these criteria will be by self-report at screening interview
- Subject has a medical condition or disorder that:
- Is unstable and clinically significant, or:
- Specifically impact immune functioning of the GI tract including Crohn's disease
and ulcerative colitis
- Require either chronic or periodic antibiotic treatment
- Could interfere with the accurate assessment of safety or efficacy of the
clinical assessments, including:
- Individuals with any:
o Current participation in any clinical trial that might impact results of this one,
which includes participation in another clinical trial where any experimental drugs
are being taken as well as studies / drug trials with agents that might affect mood
and or the gastrointestinal tract.
- Reasonable likelihood for non-compliance with the protocol for any other reason, in
the opinion of the Investigator, prohibits enrollment of subject into the study.
- Any clinically significant autoimmune disease (compensated hypothyroidism allowed)