Q: My son has peanut and tree nut allergies and we now own a dog, and on weekdays she is walked by a service. As some dog treats contain peanut butter or nut ingredients, should I be concerned about what the walker feeds the dog? Is there any risk of a serous allergic reaction?
Dr. Sharma: As you point out, pet food can be unexpected source of allergens, particularly peanut. The risk from your dog depends on the route of exposure to your son. If the dog ate a peanut-containing food and then licked an area with intact skin, the reaction would likely be confined to a skin rash (hives) in the area of contact.
In a study of 281 children with peanut allergy who had peanut butter applied to an area of skin for 15 minutes, 41 percent developed hives where the peanut butter had touched. None experienced a systemic, or widespread allergic reaction.
Now, if the area licked is instead around the mouth, nose or eyes, the dog’s saliva could, in theory, transfer some peanut allergen through the mucus membranes and trigger a more widespread reaction. For example, studies have detected peanut allergen in human saliva up to a few hours after eating peanut, and 5 to 16 percent of food-allergic individuals have reported reactions through kissing.
In addition, the risk depends on the age of your child as there have been anecdotal cases of young children with peanut allergy experiencing allergic reactions after directly playing with or ingesting peanut-containing pet food. Be sure to discuss with your child’s allergist, but for all of these reasons, the safest decision may be to ask the walker to stick with peanut- and nut-free dog treats.
Dr. Sharma is an allergist, clinical researcher and assistant professor of pediatrics. He is Clinical Chief of the Division of Allergy and Immunology at Children’s National Health System in Washington, D.C. and Director of the Food Allergy Program. Questions submitted below will be considered for answer in the magazine.