Dog bacteria might benefit human health

Netzin Steklis plays with her black lab Orion.
Netzin Steklis plays with her black lab Orion.

Fido’s licks and tummy rubs just might be good for your health.

Arizona researchers are studying the biological connection between humans and dogs that could be shared through saliva, skin, and even feces.

Scientists at the University of Arizona created the Human-Animal Interaction Research Initiative (HAIRI) to study the health links between humans and animals.

“We’ve noticed that the human-non-human interaction is something that happens all around us, all the time,” said Netzin Steklis, a lecturer in Family Studies and Human Development at UA and co-founder of HAIRI.

Animal behavior specialists Netzin Steklis and Dieter Steklis study the relationship between humans and apes, and they aim to translate their knowledge to other animal-human relationships. The couple owns Orion, an 8-year-old black Lab that is more of a family member than a pet.

“It’s a peculiar human occupation, to hang out with animals,” said Dieter, professor of Psychology and Anthropology at UA. “Under natural circumstances, this is something we’ve done for hundreds of thousands of years. It’s a mutual relationship.”

This relationship is the backbone of HAIRI’s research into “Dogs as Probiotics.” Founded in October, HAIRI has gathered researchers from around UA and Arizona, and research on dogs is their first undertaking.

The study was partly inspired by recent research at the University of Colorado Boulder in 2013, where a study showed married couples share more “microbiota” with their dog than with one another.   

Beneficial bacteria on skin and in the gastrointestinal tract help prevent inflammation and other disease-causing bacteria. The study found that not only do people share this microbiome by cohabiting an environment, but their dogs actually share more of this gut bacteria with them than other humans.

“We know kids in the West that are raised with animals, particularly dogs, show less autoimmune disorders,” said Kim Kelly, a doctoral student in medical anthropology at the UA and HAIRI program coordinator. “That means something is going on. How did humans coevolve with dogs and what does that mean for our modern day relationship with dogs?”

Partnering with the Humane Society of Southern Arizona, HAIRI will pair older adults in Arizona with foster dogs, and over the course of three months their health will be monitored and compared by testing saliva, skin, and fecal samples.

“We’re hoping we’ll see a correlation between positive microbes being passed from the dog to the human,” Kelly said.

The study is currently in a recruitment phase, and researchers are seeking Arizona volunteers over the age of 50 who have not owned a dog in the past six months. They will be screened and paired with a dog from the Humane Society, which will provide veterinary care, food, and training for the duration of the study. At the end of the study, they will have the option to adopt the dog they have been paired with.

Charles Raison, the principal investigator of the study, focuses on inflammation and its subsequent development of depression. His neurobiological studies might find a link in mental health, in addition to the physical health benefits of owning a dog.

“It’s always surprised me how many diseases and disorders are linked to inflammatory processes that link back to your immune system,” Dieter said. “If having a dog actually tames your immune system, which is what it seems to do, then elderly who have a dog may have a lower chance of depressive illnesses.”

“If dogs can help with that,” said Netzin, “that’s a significant health link.”

Netzin and Dieter Steklis predict new courses about animal-human relationships will be taught at universities, new careers will become available for researchers, and possible commercial applications will cater to the relationship between people and their pets.

“Even though Arizona is chock-full of animal-assisted therapy,” said Netzin, “there isn’t such an institute in this state, or even this region. So this is a clear need. This feeds into our ‘animality,’ which is that we have this interest, this curiosity, this love (for animals).”

Data collection is expected to be completed by the end of August, and HAIRI is currently in the development phase of studying “animality” as well as equine therapy for children with autism, which calms and focuses them through horseback riding. HAIRI’s list of research topics continues to grow as they ask questions and connect with others interested in this new area of study.

“For a long time it seemed like a non-legitimate area of scientific study,” Netzin said. “Now it’s reached legitimacy. Now it’s entered into mainstream science.”

HAIRI is not alone in Arizona dog research. Translational Genomics Research Institute (TGen), in Phoenix, aims to translate genomic discoveries about dogs in order to benefit both humans and canines.

The Program for Canine Health & Performance through TGen seeks to discover canine genetic links in cancer, deafness, inflammation, and movement disorders among other maladies that strike both species.

TGen’s canine research is also unique to Arizona, and the research being conducted in comparison to human health is a relatively new enterprise, according to Victoria Zismann, a key researcher for the TGen’s Canine Hereditary Cancer Consortium.

Zismann examines melanoma in dogs, and seeks to translate the knowledge gained about a dog’s progression of cancer to humans. Most melanoma in canines is oral, an area not exposed to the sun. This varies from human melanoma cases, which stem mostly from sun exposure. Zismann believes using canine melanoma as a model of study will provide insight into human mucosal melanoma, a relatively rare cancer that receives less attention.

“With all the advancements in science within the last 10 years or so in genomic profiling, we can look at a whole organism’s genome all at once,” Zismann said. “We’re seeing some of the same mutations, the same occurrences between us and canines, which is something we’ve never been able to do with prior technology.”

Dogs are one of few animals that develop naturally occurring cancers, similar to spontaneous cancers in humans. Because humans and canines generally share an environment, TGen seeks to find the link between the cancers, which may be more prominent than originally believed.

“Do dogs respond to the same cancer treatments as humans?” wonders Zismann. “Can we learn things that maybe we can translate to humans?”

Because dogs have a shorter life span than humans, they have a compressed disease cycle that is easier to study over a shorter period of time. According to TGen, an example of human disease research may require 4,000 samples, but a parallel study of dogs may only require 30 samples.

Samples are gathered from veterinarian offices of dogs diagnosed with cancer, regardless of their breed. The researchers also collect control samples from healthy dogs, particularly purebred dogs that have carried down their genetic predispositions through thousands of years.

“You have a greater chance of finding a predisposition in something that is less complex than you do in the human,” Zismann said.

The Program for Canine Health & Performance is also currently researching other areas of dog health, including Obsessive Compulsive Disorder or Interstitial Pulmonary Fibrosis in terriers, deafness and hearing health, and neurological canine predispositions.

“Dog owners have been one of the most open and caring people I’ve worked with,” said Zismann. “If their dog is sick, they’re wonderful about finding the best help and wanting to become part of our studies—so they can help other dogs, too.”

Kalli Ricka Wolf is a reporter for Arizona Sonora News, a service from the School of Journalism with the University of Arizona. Contact her at

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