Published online: April 20, 2018
Pet ownership is common in U.S. households. Both dogs and cats are important sources of endotoxin, which is a structural component of the cell membrane of certain bacteria. Exposure to environmental endotoxin as well as exposure to dog and cat allergens have each been associated with asthma and wheeze. However, it has been difficult to separate the impact of these exposures and whether they interact with each other to affect respiratory outcomes.
In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice, Mendy and coworkers examined whether exposure and sensitization to dog and cat influence the association of house dust endotoxin with asthma and wheeze in 6051 children and adults. The sample was drawn from the 2005-2006 cycle of the National Health and Nutrition Examination Survey (NHANES) designed to evaluate the health status of the U.S. population. In the study, exposure to dog and cat was assessed using both pet ownership data and the levels of the pets’ allergens measured in dust collected from the NHANES participants’ bedroom floor and bedding. The same dust samples were also analyzed for endotoxin content using a highly sensitive bioactivity assay. Allergic sensitization status was determined using the levels of serum immunoglobulin E (IgE) specific to dog and cat dander. Validated questionnaires were administered to the participants to collect information on current asthma and wheeze in the past 12 months, and associated morbidities.
The study confirmed the high prevalence of dog and cat ownership in the U.S. (48.3% and 37.5%, respectively) and endotoxin concentration in dust was significantly greater in the homes of participants who owned a pet. Exposure to endotoxin as well as exposure and sensitization to dog and cat allergens were each independently associated with a higher prevalence of current asthma and/or wheeze in the past 12 months, especially in adults. The association of endotoxin with the respiratory outcomes was significantly altered by exposure to pet allergens and sensitization status. In participants not sensitized to dog, exposure to high levels of dog allergen enhanced the association of endotoxin with wheeze in the past 12 months, while in participants sensitized to cat, exposure to high levels of cat allergen heightened the odds of current asthma associated with endotoxin. The concurrent exposure to high levels of both dog and cat allergens augmented the association of endotoxin with both current asthma and wheeze in the past 12 months.
The authors concluded that exposure to high levels of dog and cat allergens in homes may increase the respiratory effects of house dust endotoxin. Therefore, measures to reduce the levels of endotoxin as well as dog and cat allergens might help prevent active asthma and wheeze. This could be of particular interest to people who own dogs or cats, since they are more likely to have high levels of endotoxin and pet allergens in their homes.
The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.