For all those kids fighting a losing battle to get a puppy for the holidays, here’s a plug that may leave the parents speechless.

A new study by researchers at Johns Hopkins Medicine suggests that exposure to pet dogs before age 13 may lessen the likelihood of developing schizophrenia later in life.

The authors caution more study is needed. But they also cite previous research that suggests early-in-life exposures to pets may be environmental factors that can alter the immune system through various means. Among them: allergic responses, contact with animal bacteria and viruses, changes in the microbiome and pet-related stress reduction that may affect human brain chemistry.

“Serious psychiatric disorders have been associated with alterations in the immune system linked to environmental exposures in early life, and since household pets are often among the first things with which children have close contact, it was logical for us to explore the possibilities of connection between the two,” said Robert Yolken, lead study author and chair of pediatric neurovirology at the Johns Hopkins Children’s Center.

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In the study, published this month in the journal PLOS One, Yolken and his colleagues looked at the relationship between exposure to a household pet cat or dog during the first 12 years of life and a later diagnosis of schizophrenia or bipolar disorder.

The researchers were surprised to see a statistically significant decrease — meaning that it was not due to chance — in the risk of a person developing schizophrenia if he or she were exposed to a dog early in life.

For the study, the researchers looked at 1,371 women and men between ages 18 and 65, including 396 people with schizophrenia and 381 with bipolar disorder. The participants were asked if they had a pet dog or cat during their first 12 years of life.

Using a statistical model, the researchers found that people who were exposed to a pet dog before their 13th birthday were as much as 24% less likely to be diagnosed later in life with schizophrenia.

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“The largest apparent protective effect was found for children who had a household pet dog at birth or were first exposed after birth but before age 3,” Yolken said.

The study results suggest there is no association, positive or negative, between bipolar disorder and being around pet dogs as an infant or young child.

And sorry to all those youngsters lobbying for a kitten.

“There was no significant associations between exposure to a household pet cat and subsequent risk of either a schizophrenia or bipolar diagnosis,” the study said.