Effects of Living with Animals on Immunity

Living with animals appears to significantly influence our immune systems, possibly lowering the odds of developing allergies, eczema, and even autoimmune disorders.

The Amish community, known for its distinct lifestyle since migrating from Central Europe to North America in the 18th century, continues to practice traditional dairy farming and horse transport methods that have been passed down for generations.

This lifestyle offers insight into how our immune systems function and how closely intertwined they are with the animals we live with.

To delve deeper into why the Amish experience lower rates of specific immune-related conditions, researchers gathered in 2012 to study an Amish group in Indiana alongside the Hutterites, another farming community in South Dakota. Blood samples from 30 children in both communities provided a detailed look at their immune systems.

A striking contrast emerged: while the Hutterites adopted modern industrial farming techniques, the Amish remained connected to their animals from a young age, living in constant interaction with them and the myriad microbes they harbor.

“Drone imagery clearly shows that Amish families live alongside animals, in stark contrast to Hutterites, who often reside in small communities with farms situated miles away,” observes Fergus Shanahan, a professor emeritus at University College Cork in Ireland.

…Research suggests that a child’s likelihood of developing allergies between the ages of seven to nine decreases as the number of pets in their early lives increases, a phenomenon termed the ‘mini-farm effect.’

In a pivotal 2016 study from researchers in the US and Germany, findings indicated that Amish children are less prone to allergies due to their unique environmental influences on their immune systems. Notably, these children exhibited more refined regulatory T cells, essential for moderating atypical immune responses.

Researchers examining dust samples from the households of Amish and Hutterite children detected more microbial exposure among the Amish, likely stemming from the animals in their vicinity.

Similar studies worldwide reveal consistent outcomes. For instance, immunologists found that kids on Alpine farms, where cows are closely housed with humans, display reduced rates of asthma, hay fever, and eczema. Additionally, studies found that increased pet presence can reduce the allergy risk in young children.

“While not a blanket solution—many who grew up on farms do have allergies—it seems that interactions with farm animals can halve the chances of developing asthma or allergies,” shares Jack Gilbert, a professor at the University of California San Diego involved in the Amish research.

Pet Benefits

Since the Amish study emerged, the potential advantages of childhood interactions with animals have drawn considerable interest, even prompting discussions in media about whether pets could serve as modern-day probiotics.

So what’s the underlying mechanism? Unsurprisingly, humans, noted for their love of physical touch with pets, may inadvertently transfer microbes from their animals onto their skin.

This raises the intriguing probability that our microbiomes—comprising numerous microbes residing on our skin, in our mouths, and particularly in our guts—could be influenced by pet interactions. Nasia Safdar, an infectious disease expert at the University of Wisconsin, highlights a budding interest in the pet food industry around this concept, where developing pet products could enhance the growth of beneficial bacteria, aiming for a transfer effect to humans.

Safdar is contemplating a study to analyze fecal samples from pets and their human owners during veterinary visits to assess their microbial similarities over time.

However, skepticism exists regarding the idea of pet microbes being integrated into our bodies. Gilbert asserts that there’s no substantial proof of long-term bacterial integration from pets into human microbiomes.

Yet, Safdar maintains that it’s worth exploring the plausible transfer of gut microbes between pets and humans, arguing for more in-depth research.

According to Gilbert, pets serve a different but equally crucial role. He theorizes that as humans domesticated animals, our immune systems evolved to react positively to microbes they introduce, stimulating immune development without long-term residence.

“Over countless generations, we’ve grown accustomed to the microorganisms of dogs, horses, and cows. Our immune systems recognize their signals, fostering optimal development,” he explains.

Ancient Microbial Influence

This all paints a hopeful picture for pet enthusiasts, as research indicates that cohabitating with animals may bolster our immune systems throughout life.

Shanahan, inspired by the Amish and Hutterite studies, is undertaking research with Irish travelers, a group typically living closely with various animals. He discovered that their gut microbiomes bear more resemblance to indigenous populations that maintain traditional lifestyles, rather than modern Irish citizens.

Interestingly, his findings suggest that this could account for the notably low rates of autoimmune diseases like inflammatory bowel disorders among Irish travelers—conditions that have surged in recent times.

While this doesn’t imply that the health of Irish travelers is unblemished—they face different struggles leading to premature death—it’s noteworthy that certain autoimmune issues appear absent in this demographic.

Now, others are investigating ways to restore animal interactions in modern life to enhance health. For instance, studies at the University of Arizona have looked into how rehoming dogs can improve physical and mental health in older adults, while Italian research involving interactions with horses showed positive effects on children’s gut microbiomes.

Gilbert suggests that increased exposure to diverse bacteria through animals could enhance immunity. “Engaging with a variety of microbes might boost the immune system’s responsiveness in managing those present in our bodies,” he notes, although he stresses that long-term colonization by animal-specific bacteria doesn’t occur.

Moreover, having pets can encourage outdoor activities, which can expose individuals to more microbes beneficial for health. According to Liam O’Mahoney, a professor at APC Microbiome Ireland, having a dog typically means more regular walks, and thus greater interaction with varied environmental microbes.