Dogs and Their Owners Share Similar Allergies

Dogs and owners who live in the city are more likely to share allergies.

Posted Jan 19, 2021

Ed Yourdon/Creative Commons Licence  CC BY-NC-SA 2.0
Source: Ed Yourdon/Creative Commons Licence CC BY-NC-SA 2.0

Just how alike are you and your dog? Over the past two or three decades, data has been accumulating showing that there are many similarities in various psychological and physical characteristics between dogs and their owners.

For example, dogs and their owners seem to share certain emotional and personality characteristics. Even the popular belief that, to some extent, dogs and their owners look alike has been shown to be true in some respects. Most recently, research coming out of Finland seems to be telling us that dogs and their owners may also share common allergic sensitivities.

Why should people and their canine companions have the same allergies? A research team headed by Jenni Lehtimäki of the Finnish Environment Institute at the University of Helsinki seems to have the answer. The first hint comes from the fact that in urban environments, allergic diseases are more common among dogs and their owners when compared to those living in rural areas. That suggests that there may be an environmental factor. These investigators believe that this is associated with the microbiota of canines and people. Microbiota is the scientific term for the collection of microorganisms that live on the body. Specific clusters of microbiota are found on the skin, in the gastrointestinal tract, mouth, vagina, and also the eyes.

The nature of the microbiota varies from one environment to another and has also been systematically changing over time. If you ask your grandparents, it is likely that when they were children they probably had never heard about anyone being allergic to milk or peanuts. They also probably didn't know anybody who suffered from asthma. This is quite different from the present situation. I would certainly bet that you know people with clusters of food allergies, or asthma, or atopic dermatitis. Allergic diseases are more and more common and they have been on the rise for the past 30 or 40 years. There has been a lot of research done to attempt to explain the reason why, but recently, data has shown that the crucial factor may be the microbiota.

The relationship between individuals and their microbiota is often symbiotic since the microbiota seems to shape the immune system response of mammals. In many animals, the immune system and the microbiota may engage in a sort of cross-talk which in effect trains the immune system by activating pattern recognition receptor cells in the host individual. These cells are used to recognize dangers and repair damage. However various factors, including pathogens, can influence this normally beneficial relationship, and this can lead to inflammation, autoimmune diseases and allergies.

In the current study, a total of 168 dog-owner pairs living in rural and urban environments were tested. The testing was extensive, involving skin swabs for the dog and the person, blood tests, analysis of fecal samples, and an extensive questionnaire looking for common allergic symptoms for both the canines and humans in the sample.

The results suggest that allergies based upon the skin microbiota are most commonly shared by dogs and people. The researchers suggest that the more varied the environmental exposure to different microbial sources is, the fewer the overall number of allergic symptoms are. Because dogs and people living in an urban environment spend more time indoors, they have less exposure to the variety of microbes that individuals living in a rural setting might have.

"Research shows that dogs and owners living in rural areas have a lower risk of developing an allergic disease compared to urban areas. We assumed that in rural areas both dogs and owners are exposed to health-promoting microbes. We found that the microbial exposure of both was different in rural and urban environments. For instance, the skin microbiota varied more between individuals in rural areas compared to their urban counterparts. A diverse and varying microbial exposure may be precisely what provides the associated health benefit,” reported Senior Researcher Jenni Lehtimäki.

Professor Hannes Lohi from the University of Helsinki, another member of the research team, summarized the results saying, "For both dogs and humans, the risk of developing allergic diseases was at its lowest when the skin microbiota was shaped by a rural environment and a lifestyle that promotes microbial abundance."

The conclusion reached by this investigation is that because of the shared microbiota for dogs and their owners, dogs are more likely to have allergies when their owners also suffer from allergic symptoms.

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Jenni Lehtimäki, Hanna Sinkko, Anna Hielm-Björkman, Tiina Laatikainen, Lasse Ruokolainen, Hannes Lohi (2020). Simultaneous allergic traits in dogs and their owners are associated with living environment, lifestyle and microbial exposures. Scientific Reports. DOI:10.1038/s41598-020-79055-x