In fact children exposed to two or more dogs in the home may be slightly protected from developing itchy skin rashes. Dr. Esmeralda Morales from the University of Arizona in Tucson, USA, studied 486 children from birth to one year old.

Parents were asked how many cats and dogs they had at home at the time the child was born. Their answers were compared with the number of children diagnosed with eczema by their first birthday.

Exposure to Pets May Have Protective Effect

Of 134 children whose households had cats, 28 percent developed eczema, compared with 18 percent of 286 from cat-free homes.

Surprisingly, exposure to cats increased eczema risk more if a child's mother did not have asthma.

Previous studies have found that people susceptible to eczema are also more likely to suffer other allergy conditions, including asthma and hay fever.

Many experts believe exposure to pets at an early age may help immunize children against allergies.

This appears to be the case with dogs, at least to some extent. The study found that having more than one dog was slightly protective, but the effect was not significant.

Findings Raise More Questions

Dr. Morales, who presented her findings at the American Thoracic Society International Conference in San Diego, California, said: "Other studies have found that having cats and 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."

It was possible the one-year-olds with eczema might have a reduced risk of asthma or other allergic diseases later in life, she said, adding: "The findings do seem to add more questions about pets and asthma and allergies."