- In North America, asthma is the third-leading cause of hospitalization among children.
- It is feared that dogs and cats shed dander and stir up dust and dirt which may trigger an allergic response and cause an asthma attack.
- Two studies show that having a dog or a cat in the house can actually reduce the likelihood that a child will develop allergies and asthma.
Many studies have demonstrated the psychological, physiological, and social benefits of our interactions with animals — especially dogs. At the same time, there is a wide spread belief that dogs and cats pose potential health problems since they can activate allergic diseases such as asthma. This is because furry pets produce dander, which is made up of proteins from hair, skin flakes, and saliva. Dander can often act as an allergen that can trigger attacks of asthma and respiratory distress.
Are Kids at Risk?
I was reminded of these concerns when I recently received a very emotional phone call from a former student of mine. She and her husband had been trying to have a baby for quite a while, and she was finally a couple of months pregnant. She had had an earlier miscarriage and her husband, Jack, was showing signs of being very anxious about her health during this new pregnancy. He was also understandably preoccupied with the future health of their expected child. She explained to me that Jack had gone for some routine blood tests and while in the lab waiting room had picked up a pamphlet on the management and prevention of asthma. The pamphlet explained that 6 million American children live with asthma and it is the third-leading cause of hospitalization among children.
In a shaking voice, she read me a passage from the pamphlet which went something like this: "Medical researchers suggest that a number of factors predict asthma, including genetics. However, the consensus is that things in the child's environment, such as tobacco smoke, or more frequently exposure to a cat or a dog in the household are major contributors to the onset of the condition. The best course is to remove the pet from your home. This isn't usually the easiest or happiest solution, but it is best for the child."
She now sounded as if she was starting to cry as she went on to say, "Because of this Jack wants me to get rid of Foxy [her little Pomeranian dog] and Elsabeth [her cat]. It hurts so much to even think about doing that. Is it really necessary?"
Not So Bad After All
The advice in that pamphlet mimics the kinds of statements that one can find on many sites on the Internet. However, such advice is unnecessarily alarmist. It is certainly the case that if a child already has asthma and established allergies, a dog or a cat in the house might trigger symptoms. However, a substantial body of research has been published which shows that exposure to a dog or a cat while an individual is young actually serves to prevent the onset of asthma and allergies.
By happenstance, just a few days before I received her phone call, I had read a report whose lead author was Yu Taniguchi of the National Institute for Environmental Studies in Japan. It was an Internet survey of 4317 individuals and included 2030 dog and/or cat owners and 2287 non-pet owners. It specifically looked at the effect of pets in the household on the likelihood that children in the home would develop asthma or allergies. The results were quite unambiguous: The risk of a child developing asthma was actually cut in half if they grew up living with a dog or a cat. The protective value of living with a feline versus a canine was about the same.
Pets Protect Kids from Developing Allergies
Another recent study which came to similar conclusions was conducted in Sweden. The lead author was Bill Hesselmar of the Department of Paediatrics at the University of Gothenburg. It involved two separate groups, one of which was 1020 children aged 7 to 8 years, who were assessed for allergies and asthma. A second group of 249 had been tracked by pediatricians from birth to age 8 or 9 and were systematically tested for allergy and asthmatic symptoms over that time span. As in the case of the Japanese study, living with pets, especially during the first year of life, reduced the likelihood that asthma would develop. Furthermore, it reduced the risk that the children would develop a broad range of other environmental allergies as well.
Perhaps the most interesting finding of this study was that it indicated a "dose-dependent" effect. That means that the more dogs and cats that the young child was exposed to the smaller the likelihood was that they would suffer from allergies and asthma.
The Hygiene Hypothesis
Why does living with furry pets in the home produce such a protective effect? In both of these studies, the researchers say that they don't know for sure what explains the link between early exposure to animals and a reduced risk of asthma and allergies. Perhaps the most likely answer involves something called the "Hygiene Hypothesis." This theory suggests that being exposed to bacteria, dust, and dirt early in life is crucial for developing a healthy immune system. The suggestion is that the immune system must be challenged early in life to be strengthened to the degree that allergies and asthma can be fended off in later life. Simply put, exposure to the typical dust, debris, and dander that dogs and cats stir up or track into a household may, in the end, be healthier than living in a sanitized pet-free environment.
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Taniguchi Y, Kobayashi M (2023) Exposure to dogs and cats and risk of asthma: A retrospective study. PLoS ONE 18(3): e0282184. https://doi.org/10.1371/journal.pone.0282184
Hesselmar B, Hicke-Roberts A, Lundell AC, Adlerberth I, Rudin A, Saalman R, et al. (2018). Pet-keeping in early life reduces the risk of allergy in a dose-dependent fashion. PLoS ONE 13(12): e0208472. https://doi.org/10.1371/journal.pone.0208472