Comparison between an intradermal skin test and allergen-specific IgE-ELISA for canine atopic dermatitis

The aim of this study was to compare the results of an intradermal skin test (IDST) with those of an allergen-specific IgE-ELISA in 210 dogs with atopic dermatitis. All the dogs had a clinical diagnosis of atopic dermatitis and underwent an IDST. The sera of all dogs were analysed for allergen-specific IgE by ELISA using the monoclonal antibody D9 against dog IgE. IDST was used as the standard assay. In both methods, the following antigens provided a positive test result: Dermatophagoides farinae, Acarus siro, Tyrophagus putrescentiae, ragweed, mugwort and Lepidoglyphus destructor. ELISA had an overall sensitivity of 82.4% and an overall specificity of 93.8%. The overall accuracy of the ELISA was 91.3%. The evaluated monoclonal D9 ELISA was found to be a reliable tool for the diagnosis of those allergens that cause clinical atopy, and can be recommended for use in dogs when immunotherapy is a therapeutic option.     

The prevalence of positive intradermal allergy tests in 114 dogs with atopic dermatitis in the Bangkok metropolis, Thailand

Intradermal allergy tests using 47 selected local aero-allergens were performed on 114 dogs with atopic dermatitis. The subject animals visited the Dermatology Unit at the Veterinary Teaching Hospital of Kasetsart University or the SLV Pet Hospital with chronic pruritus and various skin lesions. Allergen extracts were composed of: 4 house dust and house dust mites, 7 household insects, 24 pollens, 11 mold spores, and Kapok. The prevalence of sensitization to various allergens were as follows: Dermatophagoides farinae (74.56%), Dermatophagoides pteronyssinus (53.51%), house dust (26.32%), American cockroach (Periplaneta americana) (23.68%), Para glass (21.93%) and mixed ants (20.18%). No relationship was noted between the various allergen groups and the location of the skin lesions except for those animals that reacted to pollens which appeared to have be more likely to have lesion affecting the perineum and tail area (p=0.022; OR, 6.429; 95% CI, 1.003-40.292).     

Effect of tiletamine/zolazepam sedation on intradermal allergy testing in atopic dogs.

Seven atopic dogs underwent intradermal allergy testing with 46 inhalant antigens before and after administration of a tiletamine/zolazepam solution (4 mg/kg of body weight, IV). This anesthetic protocol had no significant effect on the intradermal response caused by histamine, whole flea extract, or various inhalant allergens. Short-acting chemical restraint induced by the drug combination facilitated the intradermal testing procedure.     

The ACVD task force on canine atopic dermatitis (XVI): laboratory evaluation of dogs with atopic dermatitis with serum-based "allergy" tests.

Serum-based in vitro "allergy tests" are commercially available to veterinarians, and are widely used in diagnostic evaluation of a canine atopic patient. Following initial clinical diagnosis, panels of allergen-specific IgE measurements may be performed in an attempt to identify to which allergens the atopic dog is hypersensitive. Methodology for these tests varies by laboratory; few critical studies have evaluated performance of these tests, and current inter-laboratory standardization and quality control measures are inadequate. Other areas where information is critically limited include the usefulness of these tests in diagnosis of food allergy, the effect of extrinsic factors such as season of the year on results, and the influence of corticosteroid treatment on test results. Allergen-specific IgE serological tests are never completely sensitive, nor completely specific. There is only partial correlation between the serum tests and intradermal testing; however, the significance of discrepant results is unknown and unstudied. Variation in test methodologies along with the absence of universal standardization and reporting procedures have created confusion, varying study results, and an inability to compare between studies performed by different investigators.     

Effect of hyposensitization on atopic dermatitis in dogs

In a double-blind study, 51 dogs with clinically defined atopic dermatitis were injected with either alum-precipitated allergen solutions or a placebo. Comparing the treatment results of both groups on the basis of scores for clinical signs, a significant difference in clinical improvement was established in favor of the allergen-treated dogs (P less than 0.01). The proportional changes of scores for clinical signs in the allergen-treated group ranged between +27.3% and -100% (median, -61.5%) and in the placebo group between +36.4% and -100% (median, 0.0%) with respect to the initial scores. Immediate skin test reactivity disappeared only in the dogs with a good clinical response. Of 27 dogs treated with an allergen solution, 16 (59.3%) had an improvement of 51% or more. In the placebo group, 5 of 24 dogs (20.8%) reacted this way. There was total remission of the clinical signs in 9 and 4 dogs, respectively. In the dogs in which, after 9 months of hyposensitization, any improvement was observed, the chance for final improvement of more than 51% was calculated as 84%. Discriminant analysis revealed that evaluation of the effect of immunotherapy can be restricted to the 9-month follow-up examination.     

Comparison of intradermal testing and serum testing for allergen-specific IgE using monoclonal IgE antibodies in 84 atopic dogs

OBJECTIVE: To compare an ELISA measuring serum allergen-specific IgE with intradermal skin testing in canine atopic dermatitis. PROCEDURE: Eighty-four dogs with the clinical diagnosis of atopic dermatitis underwent intradermal skin testing and serum testing for allergen-specific IgE. Tests were performed in a blinded fashion. Positive reactions were compared and the sensitivity and specificity of the serum test (using intradermal skin test as the standard) were determined overall and for individual allergen groups (grass pollens, weed pollens, tree pollens, house dust mites and fleas). RESULTS: The sensitivity of the ELISA overall was 90.4%. Evaluating the individual allergen groups, the sensitivity for dust mite hypersensitivity was 95.1%, for fleas 85.4%, for tree pollens 84.3%, for grass pollens 95.1% and for weed pollens 96.4%. The specificity was 91.6% overall, for dust mites 96.3%, for fleas 92.7%, for tree pollens 95.2%, for grass pollens 94% and for weed pollens 80.7%. CONCLUSION: The evaluated ELISA seemed reliable for the diagnosis of atopy in practice and can be recommended as a screening test prior to intradermal skin testing or for use in dogs when immunotherapy is not a therapeutic option.     

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

Background – The presence of important house dust and storage mite species in the microenvironment of atopic dogs has not been thoroughly investigated. Objectives – To compare the presence and population of five dust mite species (Dermatophagoides farinae, Dermatophagoides pteronyssinus, Acarus siro, Tyrophagus putrescentiae and Lepidoglyphus destructor) among households with mite‐sensitive atopic dogs (Group A), households with clinically healthy dogs (Group B) and households without pets (Group C, n = 25) in Greece. Animals – Twenty mite‐sensitive atopic dogs and 20 clinically healthy dogs. Methods – Dust samples were collected with a vacuum cleaner from owners’ mattresses (all groups) and from dogs’ sleeping areas (Groups A and B) or living room couch (Group C), once every season of the year. Following dust flotation, mites were counted and identified. Results – Dermatophagoides farinae was the most prevalent (60, 40 and 64% in Groups A, B and C, respectively), followed by D. pteronyssinus (45, 35 and 48%, respectively), whereas the three storage mites were found in fewer households. No major differences could be found between Groups A and B or between households with (Groups A and B) and without dogs (Group C) regarding the presence or numbers of the five dust mite species. Conclusions and clinical importance – The presence and population of five common house dust and storage mite species does not differ among Greek households with mite‐sensitive atopic dogs, households with healthy dogs and households without pets.     

Canine atopic dermatitis in Greece: clinical observations and the prevalence of positive intradermal test reactions in 91 spontaneous cases.

Atopic dermatitis was diagnosed in a total of 91 dogs by combining the compatible historical evidence and clinical signs with the presence of one or more positive intradermal test reactions well correlated with the exposure to the aeroallergens and the seasonality of the clinical signs. Compared to the general hospital population Yorkshire terriers, Chinese Shar-Peis and cocker spaniels showed a strong predilection. No such predilection was found regarding the sex of the animals. The age of the dogs at the onset of the clinical signs ranged from 2 months to 8 years (median: 2.5 years). Moderate to severe pruritus, noticed in all the 91 dogs, was either localized (29/91) or generalized (64/91) and non-seasonal (43/91), seasonal (19/91) or of unknown seasonality (29/91). The most common cutaneous lesions included erythema, hyperpigmentation, hypotrichosis and crusts; their body distribution was generalized (64%) or localized (36%) with the feet as the most common site of involvement. Five dogs that had unlesional skin were significantly younger and had been pruritic for a shorter period of time compared to the majority of our study population. Otitis externa (43/91) and bacterial pyoderma (30/91) were the most common conditions associated with atopic dermatitis, while the prevalence of Malassezia dermatitis was very low (2/91). Of the other allergic skin diseases flea allergic dermatitis was the most common (29/91) followed by food hypersensitivity (2 out of the 15 dogs tested). The majority of the dogs demonstrated multiple sensitivities to the 50 aeroallergens tested, while domestic mites (77/91), and particularly Dermatophagoides farinae (64/91), were the most commonly implicated. The total number of the positive intradermal test reactions was increasing parallel to the age of the dogs but it was negatively associated with the presence of skin lesions on the carpal and tarsal joints.     

Serum immunoglobulin E against storage mite allergens in dogs with atopic dermatitis

OBJECTIVE: To determine the prevalence of serum IgE against the storage mites Acarus siro, Blomia tropicalis, and Tyrophagus putrescentiae in a population of dogs with atopic dermatitis. SAMPLE POPULATION: Sera from 84 dogs with atopic dermatitis residing in various regions of the United States and Europe. PROCEDURE: Immunoblotting of sera from atopic dogs was used to identify proteins in mite extracts that bound IgE. RESULTS: 94% of the dogs had serum IgE against proteins in extracts of 1 or more of the storage mite species. Ninety-five, 92, and 89% of the storage mite-sensitive dogs had serum IgE against proteins in extracts of A siro, B tropicalis, and T putrescentiae, respectively. Eighty-two percent had serum IgE against at least 1 protein in all 3 species. Most of the major allergens had molecular weights > 80 kd. A greater percentage of the dog sera had IgE against storage mite proteins, compared with proteins of the house dust mites Dermatophagoides farinae and D pteronyssinus. CONCLUSION AND CLINICAL RELEVANCE: Many dogs with atopic dermatitis have serum IgE against many allergens of storage mites. Most of these allergens, like allergens of dust mites, had molecular weights > 80 kd. Storage mite sensitivity in dogs may be as important, if not more important, than dust mite sensitivity.     

Evaluation of cross-reactivity of allergens by use of intradermal testing in atopic dogs

OBJECTIVE: To examine cross-reactivity of aeroallergens in Colorado and surrounding states by evaluating concurrent positive reactions of related and nonrelated allergens of intradermal tests in dogs. SAMPLE POPULATION: Intradermal test results of 268 atopic dogs. PROCEDURE: A retrospective evaluation of skin test results for 268 dogs was performed. Pairs of closely related and nonrelated allergens were evaluated. Group 1 consisted of closely related allergens with demonstrated antibody cross-reactivity in humans. In group 2, allergens of the same plant group (ie, trees, grasses, or weeds) that were not closely related were paired. In group 3, allergen pairs were of different plant groups. Plant allergens were paired with dust mite allergens, animal dander, or mold spores in group 4. In the last group, allergens not derived from plants were paired. Data were evaluated twice by use of a different definition of a positive reaction. Significance of the difference between group means of log odds ratios was estimated by use of a boot-strap percentile confidence interval. RESULTS: Significant differences in the number of concurrent positive reactions were not found between related versus nonrelated grass, weed, or tree allergens. Significant differences in the number of concurrent positive reactions were found between plant allergens of different groups (ie, grasses, weeds, and trees) and plant allergens of the same groups, related or nonrelated, as well as between plant-derived and nonplant-derived allergens. Many dogs reacting to a specific allergen did not react to a closely related allergen at the same time. CONCLUSION: These results provide evidence against clinically relevant cross-reactivity and suggest that allergen-specific immunotherapy should be formulated on the basis of single allergen test results.     

Comparison of intradermal and serum testing for allergen-specific IgE using a Fcepsilon RIalpha-based assay in atopic dogs in the UK

Atopic dermatitis in dogs is a common allergic skin disease that affects substantial numbers of dogs in the UK. The purpose of this study was to compare the results of an intradermal test (IDT) and an in vitro test in a large cohort of dogs. Dogs were intradermal tested with Greer allergens (Greer Labs Inc, Lenoir, NC, USA) using standard techniques. At the same time blood samples were drawn and submitted for evaluation by ELISA using the ALLERCEPT Definitive Allergen Panels for allergen-specific IgE, a commercial assay that uses a biotinylated recombinant extracellular domain of the high affinity Fc-epsilon receptor alpha chain protein (Fcepsilon RIalpha). The allergens used in the two tests included grass, tree and weed pollens, moulds, flea saliva/whole flea extract and house dust mite species. The optical density readings from the ELISA for each allergen were compared with the results of the IDT for 265 dogs. The prevalence of positive reactions in the ELISA was equal to or greater than the results of the IDT in the case of almost all of the allergens, but two notable exceptions were the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus. These two allergens were the most common positive reactions by IDT (prevalence D. farinae 78.9%, D. pteronyssinus 66.4%). The results of the two tests were significantly different (McNemar's test, P<0.05) for 16 of the 22 allergens. The sensitivities of the ELISA compared to the IDT (where there were more than 3 dogs with positive reactions in both tests) varied between 19.3 and 77.1% (D. pteronyssinus 19.3% and D. farinae 67.9%) and the specificities varied between 64.2 and 96.6% (D. pteronyssinus 96.6% and D. farinae 89.3%).     

Erythrocyte and plasma fatty acid patterns in dogs with atopic dermatitis and healthy dogs in the same household

Recent studies have indicated that dogs with canine atopic dermatitis (CAD) may have a disorder of fatty acid metabolism: possibly low or absent activity of delta6-desaturase or delta5-desaturase, or both. To clarify this possibility, we examined the erythrocyte and plasma fatty acid patterns of 8 dogs with CAD and their 8 healthy housemates. Atopic dermatitis was diagnosed according to the criteria proposed by Willemse; other causes of dermatitis were excluded clinically and by appropriate tests. Erythrocyte ghosts were prepared from blood samples. Membrane lipids were extracted and separated by thin-layer chromatography. From plasma and lipid fractions, fatty acid content was determined by gas chromatography. In erythrocytes, but not in plasma, we observed significant differences in the fatty acid pattern that suggested a reduction in the n6 fatty acid products of the delta6- and delta5-desaturases in dogs with atopic dermatitis when compared with healthy housemates.     

Clinical trial evaluating the efficacy and safety of cyclosporine in dogs with atopic dermatitis

OBJECTIVE: To determine efficacy and safety of cyclosporine in the treatment of atopic dermatitis among dogs in North America. DESIGN: Randomized controlled (phase 1) and open-label (phase 2) trials. ANIMALS: 268 dogs with atopic dermatitis. PROCEDURE: In phase 1, dogs were randomly assigned to be treated with cyclosporine (5 mg/kg [2.3 mg/Ib], PO, q 24 h) or a placebo. In phase 2, all dogs were treated with cyclosporine for 16 weeks. Frequency of cyclosporine administration was decreased if dogs improved clinically. RESULTS: At the end of phase 1, canine atopic dermatitis extent and severity index (CADESI) scores for dogs treated with cyclosporine were significantly lower than scores for control dogs. Percentage of dogs with severe pruritus decreased from 67% to 16% for the cyclosporine group but from 66% to only 61% for the control group. During phase 2, cyclosporine dosage was decreased to every-other-day administration in 39% of the dogs after 4 weeks. After 12 weeks, 22% of the dogs were treated twice weekly and 36% were treated every other day. After 16 weeks, CADESI score had decreased > 50% in 68% of the dogs and 47% of dogs had no or mild pruritus. The most frequent adverse reactions were gastrointestinal tract signs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cyclosporine is efficacious for the treatment of atopic dermatitis in dogs and that frequency of cyclosporine administration can be reduced following an initial induction period. The drug was well tolerated.     

Evaluation of the bacterial microflora of the conjunctival sac of healthy dogs and dogs with atopic dermatitis

The aim of this case–control study was to evaluate and compare the bacterial microflora from the conjunctival sac of dogs with atopic dermatitis and healthy dogs. Twenty‐one atopic dogs without clinical and/or cytopathological signs of bacterial blepharoconjunctivitis and 21 breed‐matched healthy dogs were enrolled. Under topical anaesthesia, the inferior conjunctival sac of one eye was scraped twice. Material was collected with a Kimura spatula, spread over a slide and stained with a Diff Quick^®‐type stain (Medion Diagnostics GmbH, Düdingen, Switzerland) for cytological examination. An area of 0.5 cm² was examined at ×1000 magnification, and the types and numbers of cells and bacteria were recorded. A bacterial swab was collected and inoculated into culture media for the growth of aerobic bacteria. Before sampling, each atopic dog was evaluated for severity of cutaneous lesions, pruritus and conjunctival inflammation. Significant differences were observed between atopic and healthy dogs for the presence of bacteria on cytology (P = 0.015), keratinized (P = 0.001) and nonkeratinized epithelial cells (P = 0.013), eosinophils (P = 0.019) and lymphocytes (P = 0.008). Bacteria were recovered from 12 atopic dogs and three healthy dogs (P = 0.004). Staphylococcus pseudintermedius was the most commonly isolated species in atopic dogs (seven of 12). In atopic dogs, no significant relation was found between conjunctival bacterial colonization (on cytology and culture) and the severity of any of the clinical parameters. This study suggests differences in conjunctival bacterial colonization and cytological features between atopic and healthy dogs.     

Pilot investigation of a model for canine atopic dermatitis: environmental house dust mite challenge of high-IgE-producing beagles, mite hypersensitive dogs with atopic dermatitis and normal dogs

Although canine atopic dermatitis (cAD) is common, few models are available. The aim of this study was to evaluate high-IgE beagles epicutaneously sensitized to house dust mite (HDM) as a possible model for cAD. Six high-IgE beagles were environmentally challenged with HDM using various doses and protocols. Similar challenge protocols were used in positive and negative control dogs: three dogs with naturally occurring cAD and positive intradermal skin test (IDT) to HDM and three normal dogs without history of skin disease and negative IDT to HDM. All high-IgE beagles and all atopic dogs developed severe cutaneous lesions and pruritus after challenge. Lesions were erythematous papules and macules in contact areas such as face, ears, ventral abdomen, groin, axillae and feet. They were first visible after 6 h and increased in severity over time. No normal dog developed pruritus or lesions. Biopsies of representative lesions in the high-IgE beagles were taken for histopathology and immunohistochemistry. There was superficial perivascular dermatitis with mononuclear infiltrates and spongiosis. Lymphocytes and eosinophils accumulated in small epidermal micro-abscesses with hyperplasia of epidermal IgE-bearing dendritic cells. These findings suggest that this colony of high-IgE beagles develops a dermatitis that clinically, histopathologically and immunologically resembles the naturally occurring canine disease. It is also concluded that this modality of challenge is not irritating to normal dogs but induces flare-ups in hypersensitive atopic dogs.     

Abnormal cutaneous response to mitogens and a contact allergen in dogs with atopic dermatitis

Antigen specific and nonspecific T-lymphocyte activity was evaluated in normal dogs and in dogs with atopic dermatitis by measuring the increase in skin thickness after application of the contact allergen dinitrochlorobenzene and after intradermal injection of the mitogens phytohemagglutinin and concanavalin A. The atopic dogs had a significantly reduced response to the contact allergen (P less than or equal to 0.001) but a significantly increased response to the mitogens (P less than or equal to 0.001). The atopic and normal dogs responded similarly to intradermally injected histamine. The response of dogs with non-atopic skin conditions to the cutaneous mitogen test was like that of normal dogs. Pre-existing dermatitis does not apparently influence cutaneous response to mitogens in dogs. The cutaneous response of atopics during treatment with corticosteroids is not different from normal controls. These results suggest a role for altered cell-mediated immunity in the pathogenesis of canine atopy and that the cutaneous mitogen test may have value as a rapid screening test for the disease.