Food Allergy in Atopic Dogs

Overview

The aim was to develop an animal model for food allergy. Twenty inbred allergic dogs were immunized as newborns and infancy with 1 µug food allergen-soy, cow’s milk, wheat, beef, rice in alum 2mg, after 3 monthly injections of 0.5ml distemper-hepatitis live virus vaccine. At 4 months, most animals made IgE antibodies to these foods. At 6 months on, food challenges with 20O–500g amounts caused significantly increased fecal index scores, and in some-facial edema, rash, and vomiting. Via gastroendoscopy, 0.1ml food extracts were injected into gastric mucosa after giving intravenous 0.5% Evans blue dye (0.25ml/kg). Within minutes, blue wheals and erythema occurred at injection sites on mucosa, none at saline control sites. Punch biopsies were taken within 10–15min. and again at 24 or 48hr. Aliquots of biopsy specimens were used for histology. Immediate reaction specimens showed edema and neutrophils. The 24 and 48hr. samples showed eosinophil and mononuclear cells infiltrations. With soy allergens-gly m-1 and Kunitz trypsin inhibitor glycinins-thioredoxin incubation for 1hr. at 25C which reduced intrachain disulfide bonds, caused marked reduction in allergenicity evidenced by reduction in skin reaction threshold with serial dilutions of allergens. The food allergic dog is a useful model for food allergy research.