Life with the family dog will give young children hours of loyal companionship, cherished memories -- and, in some cases, possibly even better health.
A study in the Journal of Pediatrics says that children with a family history of allergies may be less likely to develop eczema, an allergic skin condition, if they live with a dog when they are younger than one year.
But living with a cat may increase those odds, though only among children who are sensitive to cat allergen -- substances in pet dander, saliva and urine.
Given the complexity of the situation, it is hard to give parents specific advice about pets, said Tolly Epstein, an assistant professor at the University of Cincinnati College of Medicine in Ohio, who led the research team.
But as far as eczema goes, a number of studies have shown there is a consistent relationship among dog ownership and lower risk, she added.
"It may be that these children develop a tolerance, but we don't know that for sure," she told Reuters Health.
The study involved 636 children enrolled as infants in a long-term study of environmental exposures and allergy risk. All were considered to be at increased risk of allergies because they had a parent with a history of asthma, nasal allergies or eczema.
When the children were younger than one year, researchers visited their homes to collect dust samples.
The children also underwent yearly exams, including a skin-prick test to see whether they'd become sensitised and their immune systems were producing antibodies after being exposed to allergens such as pet dander.
Overall, 14 percent of the children had eczema at age 4. But that rate fell to 9 percent among the 184 children who'd had a dog in their home during infancy.
Of the 14 children who were sensitive to dog allergen and lived with a dog, only 2 -- 14 percent -- developed eczema. That compared to 57 percent for dog-sensitive children who didn't have a dog at home during early life.
The situation with cats is harder to call.
Epstein's team found that there was no clear relationship between having a cat in the house during infancy and an increased eczema risk among children overall, but that the picture changed with children sensitive to cat allergens.
Among 13 such children who lived with a cat during infancy, 54 percent developed eczema by age 4 compared to 33 percent who did not have a pet cat. The rate of eczema fell to 11 percent for non-sensitive children even when they did live with a cat.
Epstein noted that her study was looking specifically at the development of eczema and not other conditions, such as asthma.
She also said the results applied only to children with parents who have allergies, and little is known about how a family pet could affect children at average risk.