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.