More and more families are sharing their lives with cats and dogs. Many parents believe that not only cats and dogs teach children empathy and compassion, but they are also good for children’s health. It is also common to believe that children who grew up with cats or dogs are less likely to get asthma.
Can cats and dogs really prevent asthma in children?
Until recently, the research on asthma risk and ownership of a cat and a dog gave conflicting results. Studies showed that cat and dogs can prevent asthma while others claimed that they increase the risk of asthma (1,2); Other studies came to the conclusion that cats and dogs have no effect on asthma at all (3).
But finally, we have a study that provides us with a valuable evidence we have been waiting for: Cats can really prevent asthma in (some) children (4).
Researchers studied 377 children from Denmark whose mothers had a history of asthma. They mapped genes of these children and found that about the one-third of children carried a version of the gene called TT that significantly increases the risk of developing asthma (4).
Scientists also measured cat and dog allergen levels in dust samples from the children’s beds at age 1 year.
Variation of the gene 17q21, or in other name TT, is associated with childhood asthma. Exposure to a cat may prevent asthma in children with this particular gene. However, exposure to a dog has no such effect.
The results of the study showed that cats had a protective effect on children who were unlucky enough to have TT gene. Moreover, it seems that exposure to cats not only prevents asthma but lung infections, pneumonia and bronchiolitis too.
However, the same positive effects of cats were not found in other children without TT gene.
Surprisingly, unlike cats, dogs made absolutely no difference in reducing asthma.
Researchers are still unsure how cats deactivate the asthma gene. Jakob Stokholm, an author of the study, suspects that the bacteria that cats carry and fungi or viruses that they bring into the home have an influence on children’s immune system (5).
It is still a mystery how long parents should expose their children to cats in order to lower the risk of asthma.
Although we have some solid science that confirms that children living with cats have a better health, at least when it comes to asthma, there may be some disadvantages as well.
The same team of researchers who have just published a study on asthma we described in this article, reported that cats may trigger eczema in children (6).
Cover photo: Suzy Mead
Nafstad, P., Magnus, P., Gaarder, P. I., & Jaakkola, J. J. K. (2001). Exposure to pets and atopy‐related diseases in the first 4 years of life. Allergy, 56(4), 307-312.
2. Apelberg, B. J., Aoki, Y., & Jaakkola, J. J. (2001). Systematic review: Exposure to pets and risk of asthma and asthma-like symptoms. Journal of Allergy and Clinical Immunology, 107(3), 455-460.
3. Carlsen, K. C. L., Roll, S., Carlsen, K. H., Mowinckel, P., Wijga, A. H., Brunekreef, B., … & Krämer, U. (2012). Does pet ownership in infancy lead to asthma or allergy at school age? Pooled analysis of individual participant data from 11 European birth cohorts. PloS one, 7(8), e43214.
4. Stokholm, J., Chawes, B. L., Vissing, N., Bønnelykke, K., & Bisgaard, H. (2017). Cat exposure in early life decreases asthma risk from the 17q21 high-risk variant. Journal of Allergy and Clinical Immunology.
5.Hoffmann T. (2017, 7 Kasım). Cats protect newborns against asthma. Science Nordic.
6. Bisgaard, H., Simpson, A., Palmer, C. N., Bønnelykke, K., Mclean, I., Mukhopadhyay, S., … & Woodcock, A. (2008). Gene-environment interaction in the onset of eczema in infancy: filaggrin loss-of-function mutations enhanced by neonatal cat exposure. PLoS medicine, 5(6),