Pets in Schools
Dr. Robert Schellenberg, M.D., F.R.C.P. (C), Professor, Dept. of Medicine, UBC, Head of the Division of Allergy & Immunology at UBC and St. Paul's Hospital, Vancouver, BC
I am concerned with any school policy which exposes allergic children to animals. Animals are very potent sensitizers and repeated exposure to them can induce allergic conditions such as asthma in individuals who have not previously had the disease. I have personally been associated with two cases in my own hospital where adults developed asthma for the first time following inadvertent exposure to animal allergens despite the fact that neither individual worked directly with the animals and was only exposed through the ventilating system. This raises my first concern that, if animals are housed within a school, the allergen is circulated to every room if there are common cold air returns through forced air heating.
The second problem relates to the difficulty in associating increased asthma symptoms with a specific factor. Pet exposure in sensitized individuals frequently presents with late asthmatic symptoms, that is asthma coming on 4 to 12 hours after the exposure rather than acutely. Therefore, the child or parent of a child developing asthma in the evening may not associate that disease with the fact that they were exposed to an animal during the day.
My third concern relates to the fact that any allergen exposure increases non-specific airway hyper- responsiveness as has been documented for many different types of allergen. This means that the airways of the asthmatic narrow much more strikingly than those of a normal person and can be linked to a host of factors, be they allergenic or non-allergenic such as cold air or exercise. Therefore, the asthmatic might not note a specific attack related to pet exposure but will subsequently have worsening asthma at all other times.
For the above-mentioned reasons, it is critical that susceptible individuals not receive exposure to animal allergens and that animals not be chronically maintained in a school setting unless separate ventilation is available. Since approximately 25% of the population is allergic in one form or another (hay fever, eczema or asthma) and up to 10% have asthma, any school population will have children predisposed to allergic symptoms even if they are not currently allergic to animals. In addition, I am sure every school system has children who are already allergic to animals and will definitely have worsening disease.
from Allergy & Asthma News, Issue 1 2007