As global allergy rates continue to climb, researchers are actively investigating how childhood environments influence the development of conditions such as asthma and eczema. A prevailing theory, the “hygiene hypothesis,” suggests that modern indoor lifestyles limit early exposure to germs, potentially hindering immune system training. However, emerging evidence indicates that having a pet during childhood may counteract this effect by introducing a variety of germs and allergens into the home.
Understanding Allergies and Immunity
During the early years of life, children’s immune systems learn to differentiate between harmful and harmless substances. Allergic conditions arise when the immune system overreacts to benign elements like dust and pollen. Some researchers, like Samantha Chan from the Allergy and Immunology Foundation Australia, point out that the microbiome—the community of microorganisms in our bodies—plays a crucial role in immune function. Disruptions in this delicate balance can lead to inflammation and disease.
Studies have shown that children raised on farms, who are regularly exposed to animals and diverse environments, tend to have lower rates of allergies. These children often develop a more varied microbiome, which might make their immune systems more tolerant and less prone to allergies. In contrast, urban living, which increasingly characterizes childhood environments worldwide, offers fewer opportunities for such exposure.
The Role of Pets in Allergy Prevention
Research examining the impact of pets on allergy development has yielded intriguing results. A review of 23 studies found that children exposed to dogs early in life were significantly less likely to develop eczema. A further study in 2025 analyzed genetic data from over 270,000 individuals, revealing that certain genes increased eczema risk only in children without early dog exposure. This suggests that having a dog might offer protective benefits against eczema for genetically predisposed children.
When it comes to asthma, the findings are more complex. A 2001 study in the USA followed over 1,000 children and found that those living with dogs had a reduced risk of frequent wheezing, a common asthma symptom. However, this was true only for children without a family history of asthma. Conversely, a 2021 Korean study noted that while having a dog reduced allergy risk, it slightly increased the occurrence of non-allergic wheezing, possibly due to airway irritation rather than allergens.
The influence of cats is less clear-cut. Unlike dogs, living with cats has not been consistently linked to reduced allergy risk. This may be due to the distinct types of microbes cats and dogs introduce to the household, which could differently shape the environment and immune response.
Making Informed Choices
For families considering adding a pet, the potential for reduced allergy risk is a positive factor to consider. While having a dog might not guarantee immunity from allergic conditions, it offers possible benefits alongside companionship and joy. For those unable to have pets, other strategies like encouraging outdoor play and minimizing excessive disinfectant use can also support a resilient immune system.
Both Jo Douglass and Samantha Chan, affiliated with the Snow Centre for Immune Health, highlight the importance of ongoing research in understanding and managing allergies. Their work underscores the intricate interplay between genetics, environment, and immune development, offering hope for future strategies to mitigate allergy risks.
