Do cats raise risk of child eczema?

Children raised in homes with pet cats might run an increased risk of developing allergies.

What is the story?

Parents might have concerns that their family pet could be putting their children's health at risk, following reports that early exposure to cats may raise the risk of allergies.

Children who are exposed to cats soon after birth have a 50 per cent increased risk of developing eczema, the media claimed.

They also reported that while family cats could be to blame for children's rashes and wheezes, keeping up to two dogs actually reduced children's risk of developing allergies.

What is the research?

The reports in the media are based on research presented at the American Thoracic Society's International Conference, held last month in California.

The study included 486 children who were taking part in a larger cohort study called the Infant Immune Study. At the time of birth, the children's parents were asked how many cats and dogs they had in the house. After one year, the parents were asked if any of their children had been diagnosed with eczema.

Of the 134 children with cats in their household, 28 per cent had eczema by one year of age, compared with 18 per cent of the 286 children who did not live in a household with cats.

Exposure to cats appeared to increase a child's risk of eczema whether or not its mother had asthma. However, this effect was more pronounced in those children whose mothers did not have asthma.

Children of families that had two or more dogs in the home were found to have a slightly lower risk of developing eczema, although this was not found to be statistically significant.

What do researchers say?

Lead researcher Dr Esmeralda Morales, pediatric pulmonary fellow at the University of Arizona in Tucson, told GP the link between cats in the home and childhood eczema that they found was 'surprising'.

'When we thought of carrying out this analysis, we hypothesised a protective effect from pets in the home,' she said.

Dr Morales explained that pets had been thought to protect against the development of allergies by exposing children to endotoxins.

'If a child is exposed to endotoxin early in life, the immune system may be skewed away from developing an allergic profile,' she said.

She added that her findings raised more questions about pets and allergies than they answered.

'Given the data on the protective effects of pets on subsequent allergy, it is difficult to draw real conclusions from this one observational study.

'It's possible that the children in the study who developed eczema at age one might end up having a reduced risk of asthma or other allergies later on.'

In the meantime, she recommended that people with cats should not worry about the study: 'There are a lot of contradictory data. Clearly, it's a topic that needs further research.'

What do other experts say?

Dr Sue Lewis-Jones, consultant dermatologist and spokeswoman for the British Skin Foundation, warned that getting rid of cats could actually cause an increase in a child's risk of developing allergic symptoms.

'We should be cautious about removing pets from the home environment, because children who are currently tolerant of pet dander might go on to develop an allergy when re-exposed to animal hair later on,' she said.

She also urged parents to consider the psychological impact of getting rid of family pets.

'If a pet is forcibly removed from the home, the stress and emotional impact may in itself worsen the eczema.'

In cases where children do develop a severe allergy to cats, she advises that experienced help should be sought from a dermatologist, allergist or practitioner trained in eczema and allergic diseases. Dr Lewis-Jones also noted that patients should not wait until children are older before introducing pets into their home.

She said there was 'some evidence' to suggest that children who were exposed to cats early in life developed tolerance, whereas late exposure was more likely to lead to allergy.

Professor Jonathan Brostoff, professor of allergy and environmental health at King's College London, said there had been many 'superb' studies that contradicted the latest findings.

He cited one study which showed that babies raised in homes where two or more dogs or cats were kept were up to 77 per cent less likely to develop allergies at the age of six than those raised without pets.

GPletters@haynet.com

American Thoracic Society; Live links at GPonline.com

INFORMING PATIENTS

- A US study found that cats might increase a child's risk of developing eczema, while dogs reduce the risk.

- This contradicts previous studies suggesting that cat ownership helps to protect children from allergies.

- More research is needed.

WHAT THE PAPERS SAID
"Family cat is in the dock over children's rashes" The Times
"Cats may raise allergy risk in infants by 50%" Daily Mail
"Cats raise risk of child eczema" BBC

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