Having a family dog might decrease a baby’s risk of developing eczema later in childhood, a new evidence review says.

Specifically, exposure to canines appears to influence a child’s genetic risk of eczema, by blunting skin inflammation, researchers reported June 4 in the journal Allergy.

“We know that genetic make-up affects a child’s risk of developing eczema and previous studies have shown that owning a pet dog may be protective, but this is the first study to show how this may occur at a molecular level,” senior researcher Dr. Sara Brown said in a news release. She is a professor of dermatology at the University of Edinburgh in the U.K.

Episodes of eczema occur when an irritant or allergen prompts an immune response in the skin, causing patches to become dry, itchy and inflamed, researchers said in background notes.

It’s known that some people are genetically predisposed to eczema, but it’s not clear exactly how a person’s genes interact with the environment to either increase or decrease their risk of the skin disease, researchers said.

For this study, researchers analyzed data from 16 previous studies to test for interactions between 24 known genetic variants linked to eczema and a list of 18 environmental factors that might influence a baby’s susceptibility later in life.

This analysis, involving more than 25,000 people, honed that list down to seven factors that might influence a child’s risk – antibiotic use, cat ownership, dog ownership, breastfeeding, having an older sibling, smoking and hygiene.

The team then applied those findings to data from another 254,000 people, to see which genes and which environmental factors most strongly influenced eczema risk.

“Our research aims to answer some of the most difficult questions that I am asked in clinic: ‘Why does my child have eczema?’ and ‘What can I do to help protect my baby?’ ” Brown said.

That second analysis found that a baby’s exposure to dogs interacts with the genetics involved in interleukin-7, a type of immune protein called a cytokine that regulates inflammation.

Lab tests showed that dog exposure interacts with a genetic variant that might otherwise cause eczema, essentially suppressing skin inflammation by influencing the expression of interleukin-7 receptors in human skin cells.

However, researchers warned that more studies are needed to confirm these lab findings and better explain how dogs might affect human genetics in this way.

“More work is needed, but our findings mean we have a chance to intervene in the rise of allergic disease, to protect future generations,” Brown said.