Mom, Can We Get a Dog (& a Sibling)? I Don’t Want to Get Crohn’s Disease

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M Xue et al. Clinical Gastroenterology and Hepatology, Volume 22, Issue 9, 1889 – 1897.e12. Open Access! Environmental Factors Associated With Risk of Crohn’s Disease Development in the Crohn’s and Colitis Canada – Genetic, Environmental, Microbial Project

Methods: The authors prospectively followed 4289 healthy first-degree relatives (FDRs) of patients with CD from the Crohn’s and Colitis Canada – Genetic, Environmental, Microbial (CCC-GEM) project. Regression models identified environmental factors associated with future CD onset and their association with pre-disease biological factors, including altered intestinal permeability measured by urinary fractional excretion of lactulose to mannitol ratio (LMR); gut inflammation via fecal calprotectin (FCP) levels; and fecal microbiome composition through 16S rRNA sequencing.

Key findings:

  • Over a 5.62-year median follow-up, 86 FDRs developed CD
  • Living with a dog between ages 5 and 15 (hazard ratio [HR], 0.62; P = .034) was associated with decreased CD risk
  • Living with a dog was associated with reduced LMR, altered relative abundance of multiple bacterial genera, and increased Chao1 diversity.
  • Living with a large family size in the first year of life (HR, 0.43; P = .016) was associated with decreased CD risk
  • Having a bird at the time of recruitment (HR, 2.78; P = .005) was associated with an increased CD risk (though there were relatively few FDRs with birds at baseline, n=136)
  • Limitations: questionnaire-based assessments of environmental exposure can be subject to recall bias

My take (borrowed from authors): “Our findings contribute to the growing evidence supporting the potential health benefits of exposure to pets, particularly dogs, as a potential preventive strategy for individuals at risk of developing CD.” Having a dog during childhood may reduce the later risk of CD by ~40%.

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