Total and Toxocara canis larval excretory/secretory antigen‐ and allergen‐specific IgE in atopic and non‐atopic dogs

BACKGROUND Total IgE concentrations are higher in dogs than in humans. Persistent Toxocara canis larval infection is prevalent in dogs and is associated with substantial specific antibody reactions. A correlation, however, between total IgE and T. canis-specific antibody levels in dogs has not been evaluated. OBJECTIVES To determine the relationship between total IgE, T. canis-specific IgG and IgE, and allergen-specific IgE levels in atopic and non-atopic dogs, and to evaluate possible confounding factors. ANIMALS Sera of 30 atopic and 30 non-atopic client-owned dogs. METHODS Total IgE, T. canis-specific antibody and allergen-specific IgE levels were evaluated by ELISA. RESULTS Total IgE, T. canis-specific antibody and allergen-specific IgE levels were significantly higher in non-atopic compared to atopic dogs. A positive correlation was demonstrated between T. canis-specific IgG and T. canis-specific IgE; T. canis-specific IgG and total IgE; T. canis-specific IgE and total IgE; and allergen-specific IgE and total IgE. No differences were detected on the basis of age, gender, vaccination status; deworming or season between atopic and non-atopic dogs. Previous immunomodulatory treatment and cause of atopy did not influence antibody levels of atopic dogs. CONCLUSIONS Toxocara canis-specific IgE appears to be a major component of total IgE in dogs. Total and T. canis-specific IgE levels are higher in non-atopic compared to atopic dogs. It is speculated that T. canis infection may have a protective effect against the development of canine atopic dermatitis and/or that elevations in total serum IgE level are often not associated with atopic dermatitis.