Worried About Eczema? Get a Dog, but Not a Cat

The number of children with allergic eczema is rising, but the reasons for this are unclear. Our research suggests that exposure to dog allergens early in life may actually have a protective effect against developing future allergies among a high-risk population.

University of Cincinnati researchers, along with investigators from Cincinnati Children’s Hospital Medical Center found that a child who tests positive for dog allergies has a much lower risk of developing eczema at the age of 4 years if he/she has had a dog in the household before the age of 1. On the other hand, children who did not have a dog in the household and tested positive for dog allergies were four times more likely to develop the skin condition.

In this study, the investigators collected data related to 636 children who had enrolled in the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS), an epidemiology study that examined the effects of environmental particulates of allergy and respiratory health of children. The 636 children were considered at high risk for developing allergies because their parents had allergies.

The investigators were looking out for a link between pet ownership – specifically cats and dogs – and the risk of developing eczema. The children were tested every year, from the day they were born, for 17 different allergies, including foods, airborne allergens, and environmental exposures, such as diesel particulates. The children’s parents also reported on the child’s allergy symptoms and illnesses.

The study revealed that dog ownership tended to have a beneficial effect on the children with dog allergies, while cats had a negative effect on those with cat allergies.

Epstein said:

Children who owned a cat before age 1 and were allergic to cats based on allergy skin testing were 13 times more likely to develop eczema by age 4. However, children who were not allergic to cats were not at an increased risk for eczema if they owned a cat.

The researchers hope that this study may help parents of children who are considered at high risk of eventually developing eczema when choosing a pet.

What is an allergy?

When harmful bacteria enter our body, our immune system detects them and attacks them. The bacteria in this case are known as pathogens, a foreign bodies that do us harm and can cause disease. In some cases, the immune system may be misguided, and attacks a harmless substance as if it were a pathogen. For example, pollen is not a pathogen, it is harmless. But some people’s immune system attacks the pollen as if it were a pathogen. The person is allergic to pollen.

Put simply, allergy refers to a misguided reaction by the person’s immune system to a harmless substance.

A substance that triggers an allergic reaction is called an allergen. Hence, for a person with an allergy to pollen, the allergen is the pollen.

According to the NIH (National Institutes of Health, USA), the risk of developing allergies is genetic. If neither parent has an allergy, their children have a 15% risk of developing an allergy. If one parent has an allergy, the risk for his/her child is 30%. If an allergy exists in both parents, their child’s risk is 60%.

People can be allergic to a wide range of allergens, including latex, mold, cosmetics, bee stings, pets, pollen, medications, some foods, the sun, and aspirin.

“Opposing effects of cat and dog ownership and allergic sensitization on eczema in an atopic birth cohort” Epstein TG, et alJ Pediatr 2010.

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