An Urban Environment Poses Higher Risk of Dog and Owner Allergies than a Rural Environment

Written by Joyce Smith, BS. This study shows that dogs and humans can be predisposed to allergies in response to the same environmental risk factors.

Humans and pet dogs are more prone to develop allergies in urban than in rural environments due to the differing microbial exposures between the two areas. While both dogs and their owners suffer from allergies and diseases such as cancer and diabetes ¹ their disease manifestations differ. Studies have shown that rural environments offer pets and their owners’ exposure to more health-promoting microbes and a lower risk of allergies ². Farm animals and farm house-related dust, absent in an urban environment, provide microbial protection against asthma ³.  Higher risks of allergies exist where pets live with small families in contrast to large families and when they are exposed to westernized diets ⁴. Studies have also shown a difference in the skin microbiota between allergic dogs and allergic humans ^2,5 while the skin and gut microbiota of allergic humans differ from healthy humans ^6,7.

In a previous 2018 study, Lohi and colleagues found that both the living environment and living habits of canines affected their skin ² increasing their likelihood to suffer with allergies when their owners had allergic symptoms. In the present study ⁸, the researchers examined whether the simultaneous occurrence of allergies in dogs and their owners correlated with the gut and skin microbes that they shared. After recruiting 168 cohabiting dog-owner pairs, researchers obtained skin microbiota samplings and blood of dogs and their owners as well as dog fecal samples for genetic sequencing. Questionnaires regarding lifestyle, environment and allergic symptoms were completed. Allergy in dogs was based on the severity of owner-reported symptoms ².

Data analysis revealed the following:

• Dog-owner pairs living in urban environments (p=0.010) and lifestyles (p=0.028) were significantly more allergic than healthy dog-owner pairs.
• Both living and environmental lifestyles were more significantly associated with skin microbiota than with gut microbiota.
• Dogs and their owners have partially shared microbiota on skin but not in gut. The urban lifestyle increased the proportion of human skin bacteria in the dog skin microbiota (p = 0.044) while a rural lifestyle increased the amount of dog gut  bacteria in the human  gut  microbiome (p=0.028)  and the amount of human gut bacteria in the dog gut microbiome (p=0.009)

As seen in the previous study, the dog skin microbiota was affected by both living environments and living habits; however, in this study, the risk of developing allergic diseases for both dogs and humans was at its lowest when the skin microbiota was shaped by a rural environment and a lifestyle that promotes microbial abundance, such as living in a large family or one that had a number of different animals. The researchers conclude that exposure to a diverse and varying population of microbes may be the answer to their associated health benefits.

A study limitation was the absence to address the different ways in which uncontrollable factors such as air pollution can affect rural and urban living environments and lifestyle. Furthermore, the study authors  provided limited information on dog and owner diet and medication, both of which are factors that are known to shape gut microbiota structure and which may have functioned as uncontrolled confounders in the study.

Source: Lehtimäki, Jenni, Hanna Sinkko, Anna Hielm-Björkman, Tiina Laatikainen, Lasse Ruokolainen, and Hannes Lohi. “Simultaneous allergic traits in dogs and their owners are associated with living environment, lifestyle and microbial exposures.” Scientific reports 10, no. 1 (2020): 1-10.

© The Author(s) 2020. This is an Open Access article licensed under a Creative Commons Attribution 4.0 InternationalLicense, http://creativecommons.org/licenses/by/4.0/.

Click here to read the full text study.

Posted February 1, 2021.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

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