Living with dogs as a child may protect against Crohn’s disease

Jayant Dassz/Unsplash

A new study revealed that young children who grow up with a dog or in a large family may have protection later in life from Crohn’s disease.

The research was presented by Williams Turpin, PhD, the study’s senior author and a research associate with Mount Sinai Hospital in New York and the University of Toronto on May 23 during Digestive Disease Week.

“Our study seems to add to others that have explored the ‘hygiene hypothesis’ which suggests that the lack of exposure to microbes early in life may lead to lack of immune regulation toward environmental microbes,” Turpin said in a statement.

Researchers used an environmental questionnaire to collect information from nearly 4,300 first-degree relatives of people with Crohn’s disease enrolled in the Crohn’s and Colitis Canada Genetic, Environmental, and Microbial (CCC-GEM) project. Using responses to the questionnaire and historical data collected at the time of recruitment, researchers analyzed several environmental factors, including family size, the presence of dogs or cats as household pets, the number of bathrooms in the house, living on a farm, drinking unpasteurized milk, and drinking well water. The analysis also included age at the time of exposure.

The study found that exposure to dogs, particularly from ages 5 to 15, was linked with healthy gut permeability and balance between the microbes in the gut and the body’s immune response, all of which might help protect against Crohn’s disease. Similar effects were observed with exposure to dogs across all age groups.

Turpin and his team did not see the same results with cats, and they are determining the reason why. “It could potentially be because dog owners get outside more often with their pets or live in areas with more green space, which has been shown previously to protect against Crohn’s,” according to Turpin.

In addition, the research found that another protective factor seemed to be living with three or more family members in the first year of life, which was associated with microbiome composition later in life. The gut microbiome is believed to play a role in a number of health conditions, such as inflammatory bowel disease, colorectal cancer, diabetes, and high blood pressure.

Turpin and his colleagues hope their findings may assist physicians in asking detailed questions of patients to determine who is at highest risk. However, he said that the early life environmental factors were assessed by questionnaires, so caution is warranted in interpreting these results due to possible recall bias at recruitment. The reasons dog ownership and larger families appear to provide protection from Crohn’s remain unclear.