Children who are exposed to cats soon after birth may have an increased risk of developing eczema, a study suggests.
Other studies have suggested cats can be protective against eczema
But the US researchers found that being exposed to two or more dogs at home produced a slightly protective effect.
Eczema experts said it was too early to draw firm conclusions from the study, being presented at a US conference.
But they said parents should not remove pets from households as children might go on to develop allergies later in life when re-exposed to pet hair.
The team led by paediatric expert Esmeralda Morales from the University of Arizona in Tucson followed 486 children from birth.
They asked parents how many cats and dogs they had in the house when the child was born.
They then followed them up one year on to see which children had been diagnosed with eczema.
Just over 27% of 134 children with cats as pets had eczema by age one, compared with 17.8% of the 286 without cats in their household.
But of the 76 children living in houses with two or more dogs, only 13.2% (10) had eczema, compared to 22% (71 out of 324) of those who did not have the condition.
Research leader Dr Morales said: "Other studies have found that having cats or dogs at home seems to be protective against allergic diseases, so we expected to have similar findings.
"Pets are a source of a compound called endotoxin, and if a child is exposed to endotoxin early in life, the immune system may be skewed away from developing an allergic profile."
She acknowledged the findings added more questions about pets and asthma and allergies.
"Since there is a lot of contradictory data out there already, clearly it's a topic that needs further research," she said.
The study is being presented at the International Conference of the American Thoracic Society on Sunday.
Dr Sue Lewis-Jones, consultant dermatologist and British Skin Foundation spokeswoman, said the study was interesting but that it was too early to draw conclusions from it.
"There are many questions about the risk of exposure to pets and atopic diseases like eczema.
"We should be cautious about removing pets from the home environment, because children who are currently tolerant of pet hair may go on to develop an allergy when re-exposed to animal hair at a later stage," said Dr Lewis Jones.
"There is a lot of contradictory data around this subject and it is definitely one that would benefit from further research."
She added that forcibly removing a pet from the home could have an emotional impact on the child which may in itself worsen the eczema.
A spokeswoman for the Cats Protection League said: "As the researchers themselves say, most evidence shows that children who have cats as pets have a reduced risk of developing asthma and other allergies in later life, so this new piece of research is rather surprising."
She said further research to disprove this view was needed and that the league would be very interested in the results.
Cat allergy is the most common pet allergy, affecting up to 40% of asthma sufferers.
It is caused by a tiny protein in a cat's skin flakes and saliva, which is deposited on the fur when the animal grooms itself by licking.
It can trigger an allergic reaction within minutes if it is breathed in by the allergy-sufferer.
The symptoms usually include itchy eyes, sneezing, asthma and the skin rashes typical of eczema.