Dust mite species in the households of mite-sensitive dogs with atopic dermatitis

Clinical relevance of intradermal test results in atopic dogs

TOPIC AND AIMS

Canine atopic dermatitis (AD) is an inflammatory and pruritic skin disease and in most cases associated with IgE antibodies against environmental allergens. To date, the only causative therapeutic option is allergen immunotherapy (AIT). Offending allergens for AIT can be identified by intradermal testing (IDT) or serum allergen-specific IgE testing. The aim of the study was to evaluate positive IDT results considering the atopic dogs' clinical history.

MATERIAL AND METHODS

An IDT was performed on 48 atopic dogs and their owners completed a detailed questionnaire about the seasonal course of their pruritus. Results of IDT were correlated with the seasonal occurrence of pruritus.

RESULTS

The most common positive IDT reactions were observed to mite allergens (33.3-62.5 %). Prevalence of positive reactions to individual tree, grass and weed pollen ranged between 8.3 % and 25 %. Moulds and epithelial allergens produced positive reactions in only 0-6.3 %. A correlation between positive IDT reactions and course of pruritus could neither be found for perennial nor for seasonal allergens.

CONCLUSION

The evaluation of IDT reactions may not be an optimal method for identification of clinically relevant allergens in canine AD.

CLINICAL RELEVANCE

The results of this study emphasise the importance of considering clinical history in addition to allergy test results in the formulation of an allergen extract for desensitisation.

Evaluation of sensitization to the crude extract of Dermatophagoides farinae and its derived allergens, Der f 2 and Zen 1, in dogs with atopic dermatitis in Southern Brazil

BACKGROUND

Atopic dermatitis is associated with the production of IgE antibodies against environmental allergens and allergens of the house dust miteDermatophagoides farinae are frequently implicated in the disease.

OBJECTIVES

We aimed to observe the allergen-specific IgE against crudeD. farinae, Der f 2 and Zen 1 in dogs with atopic dermatitis and report if these dogs are in contact with material that could shelter mite allergens.

METHODS

100 dogs with clinical diagnosis of atopic dermatitis were included after exclusion of other forms of pruritic skin disease and dogs that already received specific or non-specific immunotherapy. These dogs were of different breeds and ages and they were presented at a veterinary teaching hospital and a private service of veterinary dermatology, both located in Curitiba, Southern Brazil. At the time of anamnesis, some questions were applied to know the possibility of these dogs having had contact with furniture and textile material which could shelter house dust mites. Sera samples were obtained and further analyzed by ELISA assay to measure serum IgE levels against these allergens with an established cut-off of 0.200 IgE optical density.

RESULTS

The allergen-specific IgE positivity against crudeD. farinae (92 %) and Zen 1 (77 %) was higher than Der f 2 (56 %). There was a correlation in sensitization to crude D. farinae and Zen 1 that was not observed between crude D. farinae and Der f 2 and Der f 2 and Zen 1. The sensitization to D. farinae and its allergens was associated with an unrestricted exposition to furniture and textile material. CONCLUSION & CLINICAL RELEVANCE: dogs with atopic dermatitis are frequently sensitized to D. farinae and its allergens, Der f 2 and Zen 1, may be considered major allergens in these dogs. Zen 1 may be the main allergen responsible for the sensitization to crude D. farinae.

Specific Dermatophagoides farinae extract for canine immunotherapy

BACKGROUND

Canine atopic dermatitis (cAD) is a pruritic allergic skin disease most often caused by Dermatophagoides farinae. Differences in the sensitization profile to D. farinae have been reported between people and dogs. However, allergic dogs traditionally have been treated with extracts intended for human immunotherapy.

HYPOTHESIS/OBJECTIVES

To develop a specific allergen immunotherapy for veterinary practice enriched in canine major allergens and to demonstrate its in vitro efficacy.

ANIMALS

Twenty privately owned dogs, clinically diagnosed with cAD, and three healthy dogs.

METHODS AND MATERIALS

A veterinary D. farinae allergen extract was manufactured and characterized compared to D. farinae extract used for human immunotherapy. The protein profile was analysed by SDS-PAGE and size exclusion chromatography and Der f 15 and Der f 18 allergens quantified by mass spectrometry. The allergenic profile was studied by immunoblot and the biological potency by enzyme-linked immunosorbent assay-inhibition assays. The extract's capacity to induce cytokine production [interleukin (IL)-10, interferon (IFN)-Ɣ] by peripheral blood mononuclear cells also was evaluated.

RESULTS

The veterinary extract showed a higher content of high molecular weight proteins, preferentially recognized by atopic dog sera. The fold-increases in Der f 15 and Der f 18 with respect to the human extract were 2.07 ± 0.32 and 1.63 ± 0.15, respectively. The veterinary extract showed higher biological potency (0.062 versus 0.132 µg required for 50% inhibition of dogs sera) compared to the human extract and induced significantly higher levels of IL-10 (1,780 pg/mL) and IFN-Ɣ (50.4 pg/mL) with respect to the negative control.

CONCLUSIONS AND CLINICAL IMPORTANCE

A veterinary D. farinae extract with a higher content of dog major allergens was developed and in vitro efficacy demonstrated by immunological parameters.

Evaluation of the concentration of allergens from mites in fur and households dust of dogs with atopic dermatitis

ABSTRACT: This study evaluated the concentration of Der p 1, Der f 1 and Blo t 5 in the fur and households of 20 dogs with atopic dermatitis (AD) and 20 healthy dogs. The diagnosis of AD was clinical based on Favrot’s criteria. Dust samples were collected with a domestic vacuum cleaner. For each site, 1m2 was vacuumed for 2 min. The samples were collected in separate filters, transferred into plastic containers, sealed and kept frozen until ELISA analysis. In the fur of atopic dogs the average concentration of Der p 1 was 0.25μg/g compared to 0.03μg/g in healthy dogs. In households with atopic dogs the highest concentrations of Der p 1 were found in carpets (2.18μg/g), followed by couches (1.53μg/g), beds (1.14μg/g), dogs’ bed linen (0.64μg/g) and floors (0.14μg/g). The concentrations of Der p 1 on carpets, couches and beds were significantly higher than in atopic dogs’ fur (p<0.05). There was no statistical difference when comparing the concentrations of Der f 1 and Blo t 5 in different environments of atopic dogs (p>0.05). The concentrations of Der p 1, Der f 1 and Blo t 5 were equivalent in atopic and non-atopic dog’s households. Among the allergens studied, Der p 1 was the most commonly found, predominantly in carpets and couches.

The influence of household pets on the composition and quantity of allergenic mite fauna within Irish homes: a preliminary investigation

Allergenic mites are responsible for inducing hypersensitive reactions in genetically predisposed people worldwide. Mites in dust from 30 Irish homes with pets (dogs, n = 23; cats, n = 7) were compared with those in 30 homes without pets. House dust mites constituted 78% of all mites recorded, with Dermatophagoides pteronyssinus (Acariformes: Pyroglyphidae) representing 57-72% of mites in furniture and mattresses in both home types compared with only 22% of mites in pet beds. Although storage mites accounted for just 13% of all mites recorded, they represented 46% of mites recorded in pet beds. Median levels of the dust mite allergen Der p 1 (µg/g) in dust samples from mattresses in homes without pets were significantly greater than in mattresses from homes with pets, reflecting the greater densities of D. pteronyssinus found in the former home category. Mite species richness was greater in homes with pets (17 species) than in homes without pets (13 species). This suggests that although the presence of pets can result in a wider variety of epidemiologically important mite species within households, increased competition among mite species may result in a more balanced mite fauna in the home, inhibiting the dominance of any one species and hence lowering allergen-associated risks.

Allergens in veterinary medicine

Allergic diseases in animals are increasingly gaining importance in veterinary practice and as research models. For intradermal testing and allergen immunotherapy, a good knowledge of relevant allergens for the individual species is of great importance. Currently, the knowledge about relevant veterinary allergens is based on sensitization rates identified by intradermal testing or serum testing for allergen-specific IgE; crude extracts are the basis for most evaluations. Only a few studies provide evidence about the molecular structure of (particularly) dust mite, insect and mould allergens in dogs and horses, respectively. In those species, some major allergens differ from those in humans. This position paper summarizes the current knowledge about relevant allergens in dogs, cats and horses.

Sensitization study of dogs with atopic dermatitis in the central region of Rio Grande do Sul

Canine atopic dermatitis (CAD) is a common dermatosis, defined as a genetic-related disease which predisposes to skin inflammation and pruritus, associated to a IgE-specific response in most of cases. Clinical diagnosis may be later complemented by skin allergy and/or serological tests. The aim of these tests is to identify possible allergens in order to enable the clinicians to select candidate antigens for allergen specific immunotherapy. In the present study 58 CAD positive animals were tested. All were submitted to the intradermal test (IDT) and screened for the presence of antibodies against different antigens using ELISA. The obtained results show a high prevalence of sensitization among the tested dogs to house dust mites and to pollen ofC. dactylon. With this work it was possible to identify the main allergens involved in immunological response of dogs with CAD living in central area of Rio Grande do Sul.