Animals and Asthma



Animals and Asthma- to have or to have not?



 Photo by Bethany King


  Photo by Bethany King
Children love animals. Parents may or may not love animals but they clearly love their children. Some parents have had the animals longer than they have had their children (surrogates?). So how does the world of asthma and allergy deal with the pet issue? Most parents shudder at the prospects of removing a beloved animal from a household while others have called in advance of the visit making their feelings on the pet known (just kidding, no one has actually called in hopes of finding a positive test to a pet but I am sure it was considered). All this makes life difficult for an asthma/allergy specialist. We are looking for allergic sensitization and the possibility that a pet(s) is a factor in their child’s asthma.The past dogma (bad choice of a word?) of allergy was to prevent sensitization by avoiding contact with highly allergenic things such as dog and cat. It is needless to say that one of the most frequently asked questions in the asthma/allergy clinic at Riley is what to do about pets. Our ideas on this topic are changing. For the record I like animals. Our family has had dogs, cats, hamsters, fish, and a Vietnamese Pot-Bellied pig. I have always tried to determine the clinical relevance of any positive test for animals and I try to work with the family on this issue. However perhaps having a pet is a good thing? Read on.

Recent research has challenged our previous recommendations regarding the role of a pet in the development of asthma and in the development of allergy. The hot topic today is a review of a publication by M. Kerkhof and colleagues titled ‘ Effects of pets on asthma development up to 8 years of age: the PIAMA study’ (Allergy 2009; 64: 1202-1208).

Background: four papers written between 1999-2003 found that a pet in the home during the early years of a child’s life prevented the development of allergy. Six reports between 1999-2004 gave mixed results as to whether or not a pet prevented the development of asthma. A meta-analysis (where the findings of a number of studies are combined) found a small (20%) increase in asthma with early pet exposure up to age 6 years. There have been no studies published regarding the relationship of pet exposure after the first few years of life and the development of asthma. This study fills that void.

Purpose: the study looked at the effect of the presence of cats and dogs in the home at any age during childhood and the incidence of asthma up to age 8 years.

Methods (how they studied this): This was a major survey performed in the Netherlands. There were 2951 children involved. Questionnaires were completed every year for 8 years.

Results (what they found): at age 3 months, 34 % of the children had a cat and 16% had a dog in the home.

1. When a dog was in the home, there was less allergy to house dust mites and to pollen at age 8 years.

2. The presence of a dog or cat in the home at 3 months of age was not associated with the presence of asthma or asthma symptoms when the child was 8 years old.

3. The occurrence of wheeze and a dry cough at night after age 2 years was higher in the children who had a dog in the home at the beginning of the study. The wheeze was more in boys and the dry nighttime cough favored the girls.

4. Removing a dog from the home was associated a higher incidence of wheezing (Odds Ratio = 2.59) and having a prescription for an inhaled steroid (Odds Ratio = 3.03). This was observed in the year after the removal of the animal. Note: a simple way of interpreting the Odds Ratio is that wheezing occurred 159% more and prescriptions for inhaled corticosteroids were 203% more in children where the dog was removed.

Siberian Husky - a true snow dog  Kita one of our Siberian Huskys- a real snow dog


1. Pet exposure early in life may prevent the development of allergic sensitization to pollen and house dust mites at age 8 years.

2. Exposure to pets at any age in childhood did not affect the development of asthma up to age 8 years.

3. Exposure to dogs after the first two years of life increased the transient symptoms of wheeze and dry cough.

4. Dog removal increases the risk of wheeze and the need for an inhaled steroid.

Comments: the authors point out weaknesses in their study. One weakness is the problem with having a clear definition of asthma. This is a problem for many studies like this. The authors were able to examine 1132 of the 2951 children and validated the presence of asthma with specialized tests. This becomes an issue when trying to understand the transient wheeze and dry cough. Was this truly asthma or symptoms due to a viral illness? In the discussion it was thought that this was a response to the endotoxin in the environment from the dog that stimulates immune processes away from allergy.

Another potential weakness identified by the authors is that the measurement for allergy was done in only 1248 of the children.

Studies like this start us thinking about what advice to give to families on this subject. It is important to note that this work was done in the Netherlands and not done  in this country. This concept needs to be proven in the United States.  The differences in the populations  may limit our ability to extend the findings to current clinical practices here.

When evaluating a child for asthma, I think we have to be sure of the relationship of the symptoms to the skin test findings. All too often a family is told to get rid of the pets based on the results of an initial set of allergy tests. I am not sure this is an immediate way to proceed and we need to think of other family dynamics that are involved. I have frequently taken advantage of a more sophisticated measure used in asthma care/diagnosis to help figure out the relationship between triggering events and the clinical relevance of an allergy test result. At Riley we can measure exhaled nitric oxide. eNO is a by-product of allergic airway inflammation. When it is elevated there is most probably an allergic trigger causing the symptoms. I may not consider that a positive allergy test to dog relevant when there is significant exposure and the eNO is normal during an event. The asthma episode may be triggered by something else that requires investigation.

No, I am not ready to tell all my families to obtain an array of pets in anticipation of having children. I wonder what to do for those families who do not want the expense of feeding/picking up after pets. Ccould they purchase a ‘Bag o Pet’. This would contain all those things that are responsible for preventing sensitization and the development of asthma and not the live creature. Just a quick thought.

Loki - Brandon and Amanda's Cat (the Norse god of mischief)  Loki- (Brandon and Amanda’s cat- name for the Norse god of mischief)

Fred Leickly

July 16, 2009 · fleickly · 7 Comments
Posted in: Animal Allergy, Asthma, Developing Allergy

7 Responses

  1. Rebecca Cooley - September 30, 2009

    My six-year-old daughter is allergic to cats, not dogs. A few years ago I read that there was thought to be a connection between early exposure to animals and allergy. Since then, I’ve wondered if this is true with her. Our dog’s bed was not too far from where we kept her high chair. However, her only exposure to cats was infrequent petting of our barn cats.

  2. Fred Leickly - September 30, 2009

    This keeps going back and forward. The basic idea is under the ‘Hygiene Hypothesis’. This is the thought that all babies are born with an immune system geared for allergic responses. As the child is exposed to things, the immune system changes away from being allergy prone.
    With the animals it is their endotoxin that stimulates the immune system away from allergy. Dogs are protective especially having a number of them. The same would go for cats, you have to be continuously exposed at a critical time with enough endotoxin to be non-allergic. I suppose that the intermittant cat exposure (vs. regular) was enough to cause sensitization.
    This is all a theory. Some day it will be figured out.
    Fred Leickly

  3. Rachel Papakhian - October 7, 2009

    Hi Dr. Leickly,

    I am friends with your daughter Bethany (we went to college at the same time at IU) and we both now live in the DC metro area. So we’ve been friends for years. And I know we’ve met at some point, many years ago though. I am writing because I have 7.5 month old fraternal boy girl twins (and a 5 year old) and am concerned my infant son may have allergies. He has had a cough since he was about one month old and off and on a clear runny nose. He also sneezes frequently. We have 2 cats. I am worried that his cough is not going away and am not sure what is causing it. We have discussed it with our pediatrician on a number of occasions and I am taking him back to the pediatrician on Friday (October 9th) to have him checked again. He has been exposed to cats since birth as we have had our cats for many years. Should I be concerned about a pet allergy or could it be a different environmental issue that is causing the cough? And what can I do about it? Our pediatrician has mentioned that it could very well be an allergy but that he is too young to be tested. Is this accurate? I have placed an air purifier in the bedroom right next to his crib. We take him in warm steamy showers daily and use saline in his nose. My husband has many seasonal and environmental allergies (pollen, ragweed, mold, dust) and is also allergic to ibuprofen. He is also “supposedly” allergic to cats and dogs although he is not bothered by being around them. He grew up with a dog and the dog allergy did bother him when he was younger. So I am not sure if genetics plays a role. Our 5 year old son does seem to maybe have some seasonal allergies and we are going to have him tested by a pediatric allergist next week.
    Anyhow–my main concern right now is my 7 month old son. By the way, his twin sister does not have the same symptoms, however, she does sneeze more often than I remember my now 5 year old sneezing at this age. I should also mention that my 7 month old son is very “happy go lucky” so his mood and disposition do not seem to be too impacted by this chronic cough. Could it be from the cats or possibly another environmental allergy and how can we determine this?
    I would greatly appreciate your input and your recommendations of what to do next in terms of having him evaluated/treated.
    Thank you so much.

  4. fleickly - October 8, 2009

    Greetings Rachel, this is a frequent concern- a great question. There are a couple of things here;
    1. It takes time for inhalant allergy to become apparent. Usually it takes about one year of exposures prior to the development of clinical symptoms. So, with a cough that started so early in life and one that has not changed in character, I would doubt that allergy to cat is the issue. It is just too early.
    2. Early onset cough has a fairly long differential- there are many possible causes. It sounds like the baby is thriving and in pediatrics, that is a good sign. I would start with a chest radiograph (chest X ray). This would clear up many different reasons for the cough and is a very good screen for any structural reasons for cough. Reflux disease- can trigger cough. The cough may get worse when the child is laying down.
    3. Cats- in the lore of allergy, one cat is bad however two cats may be protective! The animals have endotoxin which stimulates the child’s immune system. With two cats there may be more of a stimulation and a drive away from allergy.
    4. Too young to test- my response to that is that it matters what you are testing for. Food allergy which may be implicated in eczema can appear by the 2nd month of life and allergy skin tests are valid in that age group. Testing to inhalants prior to age one year would be too young. And testing to pollens prior to the third year of life would not be warranted (depending upon where you live and the nature of the pollen seasons). So not too young if it is food and skin, wait until after age one for inhalants and wait until after age 3 for the pollens.
    5. Other things to consider as an irritant effect for cough would be smoke, candles, incense, strong cleaning fluids, formaldehyde etc.
    I hope this gives you some guidance. Keep the questions coming,
    My humble opinion,

  5. Rachel Papakhian - October 8, 2009

    Hi again Dr. Leickly,

    First of all, thank you so much for your informative response. I really appreciate the feedback.
    Both babies are on Xantac for reflux, but the pediatrician has not indicated my son’s chronic cough is a result of the reflux (he was diagnosed with reflux months after the cough started), however,
    I will bring that up again tomorrow at the doctor’s office. It is good to know that the cats may not be an issue and that they are too young to be tested for such an allergy. I did forget to mention yesterday that neither baby has had an allergic reaction to any food they have had as of yet. No smoke, candles, or incense in the home. And we intentionally try to use “green” cleaning supplies and laundry detergent as well.
    Yes, both babies are thriving and growing and developing right on track. So it is just really this chronic cough in my son that is an issue.
    Again, thank you so much. This is incredibly helpful. I appreciate you taking time out of your busy schedule to answer my questions.

  6. Machelle Masciantonio - April 28, 2010

    i have been suffering from Asthma ever since i was little kid. i can only manage it by taking medicines and some food supplements. ~

  7. fleickly - May 8, 2010

    Asthma is a chronic condition. From the perspective of a long-time sufferer you know it requires a wide variety of treatments. Avoidance of allergens, medications, and a host of other therapies. The FDA just approved a non-medical therapy for asthma in adults that uses thermal energy to alter smooth muscle.
    There is also significant work on the role of Vitamin D.