Living Environment Influences Allergy Risk in Dogs, People

For humans, the relationship between living environment and allergies has been well established. Interestingly, interactions between a host’s microbiota and environmental microbes are thought to influence allergy development in people. In particular, urban living decreases exposure to immune-modulating environmental microbes, thus altering a person’s microbiota and increasing his or her allergy risk.

How living environment affects canine allergies, though, has been rarely studied, despite the fact that dogs and humans share similar allergies such as atopic dermatitis. Fortunately, dogs are an ideal animal model for exploring the relationship between living environment and allergies, given that dogs and humans share similar living environments and lifestyles; also, compared with laboratory mice, dogs are more genetically, physiologically, and clinically similar to humans.

RELATED:

• New Insights on Feline Skin Microbiota
• It's Spring and My Pet Itches! A Look at Seasonal Allergies

A Finnish research team sought to identify environmental risk factors for canine allergies. Their findings were recently reported in Nature Scientific Reports.

Data Analysis

Nearly 6000 Finnish dog owners completed a survey about the allergic history of their dogs, themselves, and their families; the dog’s allergic history included details about signs of allergy, outdoor activity, and diet. The researchers then used these data to develop allergy scores indicating allergy severity.

The researchers also quantified the environmental land-use of where the dogs were born and currently lived (urban or rural) and analyzed the role of several lifestyle factors on allergy scores in dogs.

Because breed heavily influences allergy risk and could be a confounding factor, the researchers controlled for breed effects by creating 2 study subsets from which known allergy-prone breeds were excluded:

• Allergy-tolerant breeds
• Common breeds: the 5 most represented breeds in the study data

Study Findings

Approximately 70% of dogs were born in rural areas and about 50% lived in rural and urban environments during the survey period. For dogs with either low or high allergy scores, living in a rural environment decreased allergy risk. Birth environment did not influence allergy risk, potentially due to the early age at which puppies are removed from their birth environment.

Several aspects of rural living were associated with lower allergy scores in dogs:

• Never visiting city areas
• Outdoor exposure and activities
• Frequent contact with farm animals
• Large family size (3 or more children)

The finding on family size could suggest bidirectional allergy protection, the researchers believed, given previous studies reporting pet dogs’ abilities to provide allergy protection.

Analysis of the relationship between house type (farm, house, row house, flat) in rural and urban environments and allergy score revealed higher allergy scores in urban areas. However, because house type was significantly associated with both allergy score and living environment, interpretation of these allergy scores was not clear, the investigators acknowledged.

For dog owners and their families, allergies were more common in urban areas than rural areas. Interestingly, allergies in dogs and their owners were often present concurrently, even when controlling for breed.

Moving Forward

The study results suggest that, overall, rural living lowers the risk of allergies in dogs. At the individual level, though, the effect of breed on allergies is likely evident, the researched believed.

The similar findings on allergy risk in dog owners indicates the general influence of living environment and lifestyle on mammalian health, they noted. To improve pet health and decrease allergy risk, the researchers recommended incorporating more green space into cities to facilitate more outdoor living.

Dr. Pendergrass received her Doctor of Veterinary Medicine degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, a medical communications company.