The ACVD task force on canine atopic dermatitis (XVII): intradermal testing

Influence of a single oral dose of trazodone on intradermal histamine reactivity in clinically healthy dogs

BACKGROUND

Drug interactions are significant considerations for intradermal testing (IDT). Trazodone (TRZ) is an anxiolytic and selective histaminergic (H1 ) antagonist with no interaction in human prick tests; however, interaction in canine IDT is unknown.

HYPOTHESIS/OBJECTIVES

Trazodone will not adversely affect intradermal histamine reactions in dogs.

ANIMALS

Fourteen nonanxious, nonatopic, healthy client-owned dogs were enrolled in this randomised, blinded, cross-over study.

MATERIALS AND METHODS

Dogs were randomised to receive low-dose TRZ (4 mg/kg) (Teva Pharmaceuticals), high-dose TRZ (8 mg/kg) or no TRZ per os two hours before intravenous sedation with dexmedetomidine (5 mcg/kg) (Dexdomitor; Zoetis). Intradermal testing was performed with five quadrupling dilutions of histamine (1:100,000 to 1:25,600,000 w/v; Greer) and 0.9% saline (Hospira), observing a minimum two weeks washout period between treatments. Two observers, who were blinded to treatment and the identity of the injections, evaluated each test using previously established subjective and objective methods.

RESULTS

The mean wheal diameter of histamine 1:1,600,000 w/v was significantly smaller with low-dose TRZ (4 mg/kg) compared to the control group (p = 0.048; repeated measures ANOVA with post hoc Tukey's test). For all other histamine dilutions and saline, mean wheal diameter was not significantly different among groups. There were no significant differences in the subjective scores of all histamine dilutions and saline (p > 0.05; Friedman test).

CONCLUSION AND CLINICAL RELEVANCE

A single oral dose of TRZ does not adversely affect intradermal histamine reactions in dogs.

A randomised, double-blinded trial to assess the effect of oclacitinib and prednisolone on intradermal allergen and prick tests in dogs with atopic dermatitis

BACKGROUND

Intradermal (IDT) and prick (PT) tests are used to select allergens for allergen-specific immunotherapy in dogs with atopic dermatitis (cAD). However, the use of antipruritic drugs before performing these tests may influence the results.

OBJECTIVE

To evaluate the influence of the drugs oclacitinib and prednisolone on the immediate-phase reactions of IDT and PT.

ANIMALS

Thirty client-owned dogs with cAD with positive reactions to at least one allergen extract on IDT or PT.

MATERIALS AND METHODS

Dogs were randomly assigned to receive oclacitinib 0.4-0.58 mg/kg per os, every 12 h (n = 14), or prednisolone 0.37-0.65 mg/kg p.o., every 12 h (n = 16) for 14 days. IDT and PT were performed on Day (D)0 before treatment and on D14.

RESULTS

At D14 there was no significant reduction in the means of the orthogonal diameters of the positive immediate-phase reactions of the IDT (p = 0.064) in the oclacitinib group; however, in the PT, the diameter of the positive reactions reduced significantly (p = 0.048). In both tests, there was no significant reduction in the total number of positive reactions (IDT, p > 0.999; PT, p = 0.735). In the prednisolone group, the means of the orthogonal diameters of positive immediate-phase reactions were significantly reduced in both tests (IDT, p = 0.001; PT, p ≤ 0.001) and there also was a reduction in the total number of positive reactions (IDT, p = 0.022; PT, p = 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE

The use of oclacitinib 0.4-0.58 mg/kg twice daily for 14 days does not interfere with IDT results in dogs with cAD. However, oclacitinib may reduce PT reactivity. The use of prednisolone 0.37-0.65 mg/kg twice daily results in a reduction in both IDT and PT results.

Pilot study to determine the concordance between skin prick and intradermal test (IDT) reactivity to environmental allergens in atopic dogs using IDT as the gold standard

BACKGROUND

Prick testing is widely used as the first-line in vivo test for environmental allergens in people owing to its noninvasive nature and speed of performance.

OBJECTIVES

To determine concordance between skin prick testing (SPT) and intradermal testing (IDT) reactivity to environmental allergen mixes in dogs with atopic dermatitis (cAD).

ANIMALS

Forty client-owned dogs with cAD.

MATERIALS AND METHODS

Skin prick testing (GREER Pick System; Stallergenes Greer) and IDT were performed on 40 dogs using seven glycerinated and aqueous environmental allergen mixes, respectively (tree, grass and weed pollens, house dust mites and three mould mixes). Reactions for IDT and SPT were evaluated both subjectively and objectively (mean wheal diameter; MWD) and compared to saline and histamine controls.

RESULTS

Using IDT as the gold standard, with subjective scoring, SPT was 47.0% sensitive [95% confidence interval (CI) 36.0%-58.7%], 92.1% specific (95% CI 87.6%-95.3%) and agreement was moderate (79%, Cohen's kappa = 0.424). The positive predictive value of SPT was 36% and negative predictive value was 95%. Objective and subjective scores had only fair agreement.

CONCLUSIONS AND CLINICAL RELEVANCE

Skin prick testing with allergen mixes was specific yet poorly sensitive as compared to IDT. For both IDT and SPT, 95% (38 of 40) dogs failed to react to an allergen mix, despite showing a positive reaction to at least one component. Future studies comparing SPT and IDT should test individual allergens rather than mixes to prevent the dilution of individual components, which may have resulted in false negatives.

Modified rush venom immunotherapy in dogs with Hymenoptera hypersensitivity

BACKGROUND

Hymenoptera envenomation occurs frequently in people and dogs and can trigger anaphylaxis. Venom immunotherapy (VIT) is the only preventive treatment for Hymenoptera hypersensitivity and is indicated for people with severe adverse reactions to insect stings. Rush VIT is an accelerated VIT protocol in people. This has not been reported in dogs.

OBJECTIVES

The objective of the study was to evaluate the safety of modified rush VIT.

ANIMALS

Twenty client-owned dogs with Hymenoptera hypersensitivity based on a history of adverse reactions to Hymenoptera envenomation and a positive intradermal test to honey bee and/or paper wasp venom.

MATERIALS AND METHODS

Dogs received incremental doses of venom via subcutaneous injection one day per week for three consecutive weeks until the maintenance dose was achieved. Vital signs were recorded every 30 min prior to venom administration. Adverse reactions were categorised as localised or grade I-IV systemic reactions.

RESULTS

Nineteen of 20 dogs (95%) completed rush VIT. One dog experienced a grade III systemic adverse reaction and was withdrawn from the study. No adverse reactions occurred in 10 of 20 dogs (50%). Localised and grade I-II systemic reactions occurred in nine of 20 dogs (45%), including nausea (n = 5), injection site pruritus (n = 3) and diarrhoea and lethargy (n = 1).

CONCLUSIONS AND CLINICAL RELEVANCE

Modified rush VIT in dogs was well-tolerated and should be considered for dogs with Hymenoptera hypersensitivity. Larger studies are needed to evaluate the efficacy of VIT in dogs for preventing hypersensitivity reactions to insect stings.

Sensitivity of a Hymenoptera serological immunoglobulin (Ig)E assay for the diagnosis of venom hypersensitivity in dogs

BACKGROUND

Hymenoptera envenomation with honey bee (Apis mellifera) and paper wasp (Polistes spp.) may cause life-threatening anaphylaxis in dogs. In human patients, clinical history, intradermal testing (IDT) and measurement of allergen-specific serological immunoglobulin (Ig)E (sIgE) are used to support a diagnosis of Hymenoptera venom hypersensitivity. The utility of venom allergen-specific sIgE has not yet been evaluated for this purpose in dogs.

OBJECTIVES

The objective of the study was to investigate the sensitivity (sn), specificity (sp) and positive predictive value (PPV) of honey bee and paper wasp serological titres using a commercially available sIgE assay [VARL (Veterinary Allergen Reference Laboratory) Liquid Gold] against clinical history for a diagnosis of Hymenoptera hypersensitivity in dogs.

MATERIALS AND METHODS

Honeybee and paper wasp IgE serum titres were measured in 15 client-owned dogs with a diagnosis of Hymenoptera venom hypersensitivity based on a history of anaphylaxis, owner observation of Hymenoptera, and positive IDT to bee and/or wasp; and in 10 client-owned dogs with no known history of anaphylaxis or Hymenoptera exposure and a negative IDT to bee and wasp.

RESULTS

Analysis of receiver operating characteristic (ROC) curves demonstrate that a VARL score cut-off of one of six for honeybee yields Sn, Sp and PPV of 40%, 60% and 60%, respectively, and two of six for wasp yields Sn, Sp and PPV of 25%, 78% and 60%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Owing to the poor sensitivity and PPV of sIgE assays for both bee and wasp hypersensitivity in dogs with known envenomation and anaphylaxis, the use of sIgE cannot be recommended as a tool for venom identification.

Alfaxalone provides reliable sedation for intradermal allergen testing in dogs and does not significantly affect results when compared to dexmedetomidine

BACKGROUND

Dexmedetomidine (Dexmedetomidine hydrochloride-Dexdomitor; Zoetis) is the preferred sedative used for canine intradermal allergen testing (IDT) in the United States. Alfaxalone (Alfaxan Multidose; Jurox Animal Health) is a neuroactive steroid, and its effect on sedation and allergen reactivity scores is unknown.

HYPOTHESIS/OBJECTIVES

We hypothesised that alfaxalone would produce an adequate level of sedation with fewer cardiovascular adverse effects and would not affect allergen reactivity scores or histamine wheal size compared to dexmedetomidine.

MATERIALS AND METHODS

Twenty client-owned dogs were included in two groups: 10 atopic and 10 nonatopic. In a randomised, controlled, blinded, cross-over design all dogs underwent two modified IDT, 1-4 weeks apart, using intravenous dexmedetomidine (2.87-5.22 μg/kg) or alfaxalone (1.8-2.4 mg/kg). Anaesthetic parameters and sedation level were recorded over 25 min using a validated canine sedation scale described by Grint et al. (Small Anim Pract, 2009, 50, 62). Simultaneously, both objective and subjective reactivity scores were measured in technical triplicates at 10, 15 and 20 min. The modified IDT included eight allergens, histamine-positive and saline-negative controls.

RESULTS

Alfaxalone produced a significantly higher sedation score across all time points (p < 0.05). All objective scores were significantly correlated to the corresponding subjective scores (Spearman R = 0.859, p < 0.0001). Sedative used did not significantly affect subjective allergen scores for nine atopic dogs (p > 0.05, 15 min). Sedative used did not affect the diameter of objective scores for individual allergens and histamine wheals (p > 0.05, 15 min).

CONCLUSIONS AND CLINICAL RELEVANCE

Intravascular alfaxalone is an alternative sedative for IDT in dogs. Alfaxalone may be preferred to dexmedetomidine in some clinical scenarios as a result of having fewer cardiovascular adverse effects.

Effect of glycerin on immediate cutaneous reactions of histamine (positive) and phosphate-buffered saline (negative) controls in intradermal skin testing of healthy dogs: A randomised, blinded study

BACKGROUND

Glycerinated allergen extracts contain 50% glycerin, an excellent preservative. While glycerin is a recognised irritant in humans, the utility of glycerinated extracts for intradermal testing has not been validated in dogs.

HYPOTHESIS/OBJECTIVE

To determine and compare the effects of glycerin on immediate cutaneous reactions to intradermal injections of histamine and saline in healthy dogs.

ANIMALS

Eight healthy laboratory beagles.

MATERIALS AND METHODS

The study was designed as a randomised, blinded study. Intradermal injections of histamine (positive control) and saline (negative control) in aqueous and glycerinated (50%) forms were performed on the right thorax. Global wheal scores (GWS) at 20 min were evaluated by two independent investigators blinded to the interventions.

RESULTS

There were no wheal and flare reactions observed after the intradermal injections of phenolated saline. By contrast, 50% glycerosaline injections induced erythema and induration in all dogs. Global wheal scores were significantly higher in aqueous histamine (Friedman test, p < 0.0001) and 50% glycerinated histamine (Friedman test, p = 0.0084) compared to phenolated saline controls. Interestingly, only aqueous histamine (Friedman test, p = 0.01) had significantly higher GWS than 50% glycerosaline injections, while no significant difference in GWS between 50% glycerinated histamine and 50% glycerosaline groups was observed (Friedman test, p = 0.59).

CONCLUSION AND CLINICAL RELEVANCE

This study demonstrates that intradermal injection of 50% glycerosaline induces erythema and induration skin reactions in healthy dogs that can mimic positive reactions to allergenic extracts. Further dilutions of glycerinated positive and negative control solutions need to be optimised for intradermal testing in dogs.

Lack of Interference of Oclacitinib with the results of intradermal testing or allergen-specific IgE serology in Dermatophagoides farinae-sensitized beagle dogs

Canine atopic dermatitis (AD) is associated with increased levels of allergen-specific IgE due to hyper-sensitization to environmental allergens. Intradermal testing (IDT) and allergen-specific IgE serology testing are often used to determine the allergens which elicit an IgE response in animals with a diagnosis of AD. The objective of this study was to determine the effects of oclacitinib on IDT and allergen-specific IgE serology testing using a laboratory model of house-dust mite sensitized Beagle dogs. Twenty-four (24) normal, healthy purpose-bred Beagle dogs were sensitized to house dust mites (HDM, Dermatophagoides farinae) and randomly assigned to placebo-, oclacitinib- (0.4 mg/kg/dose PO), or prednisolone-treated (0.5 mg/kg/dose PO) groups. After 14 days of twice daily dosing, the effects of prednisolone and oclacitinib were compared to placebo using baseline and post-dose IDT and allergen-specific IgE serum measurements. Sensitized dogs had increased circulating HDM-specific IgE for at least two weeks post-sensitization. Prednisolone significantly inhibited the measurable sensitivity of IDT, while oclacitinib did not. Neither prednisolone nor oclacitinib imposed significant effects on allergen-specific IgE serum levels, suggesting oclacitinib may have potential to be used in dogs concurrently undergoing intradermal skin testing and/or allergen-specific IgE serology testing without interference with test results.

Investigation of the diagnostic performance of prick test with two environmental allergens in dogs with atopic dermatitis: A study using intradermal test as the gold standard

BACKGROUND

There are no studies investigating the correlation between prick test (PT) and intradermal test (IDT) with environmental allergens in dogs with atopic dermatitis (AD).

OBJECTIVES

To investigate the correlation between PT and IDT for two environmental allergens, and to calculate the sensitivity, specificity and Youden index of PT, using IDT as the gold standard.

MATERIALS AND METHODS

Twenty-two dogs with AD were selected. PT was performed with glycerinated allergen extracts, along with negative and positive controls, using the Greer Prick System. Reactions were interpreted (positive/negative) subjectively and by using seven objective criteria, by an examiner blinded to the IDT results. IDT reactions to the same allergens were interpreted, subjectively and objectively, by another masked investigator. The agreement between PT and IDT, the sensitivity, specificity and Youden index of PT, using IDT as gold standard, were calculated.

RESULTS

On subjective evaluation, the correlation between PT and IDT was poor and sensitivity of PT was 0%. Of the seven criteria for the objective evaluation of PT, the best diagnostic performance was attained when allergen-induced wheals were considered positive if their longest diameter was ≥8.5 mm. However, even then, the correlation with IDT was moderate, and the sensitivity of PT, albeit based on few positive IDT reactions, was low.

CONCLUSION AND CLINICAL RELEVANCE

At least as performed herein, PT has a poor-to-moderate correlation with IDT, mainly as a consequence of the lack of positive PT reactions. Further studies are needed to improve PT technique, yet, meanwhile, it cannot be recommended as a substitute for IDT.

A 3-Year Case Report on an Atopic Patient with a Caninised Monoclonal Antibody Treatment

A 6-year-old, male, neutered, English Mastiff dog was presented for a second opinion due to chronic pruritus. The patient had been on methylprednisolone and chlorphenamine for four years. The diagnostic investigations included: swabs for bacterial and mycology culture, hair plugs for dermatophyte culture, acetate tape strips and deep skin scrapes, skin biopsies for dermatohistopathology, biochemistry, haematology, endocrinology, serology for canine scabies using enzyme-linked immunosorbent assay (ELISA) testing and serology for allergen specific IgE antibodies. The history and the diagnostics confirmed the diagnosis of canine atopic dermatitis. This case report details the treatment with lokivetmab, which is a caninised monoclonal antibody drug. At periods of flare ups, additional treatments were prescribed, such as systemic glucocorticoids and oclacitinib in order to manage the clinical signs. The treatment showed good response to the overall treatment management during the three year period of this atopic patient.

Altered plasma cytokines in dogs with atopic dermatitis

BACKGROUND

Canine (Canis lupus familiaris) atopic dermatitis (AD) shares similar clinical signs to human AD. The abnormal immune response of AD is orchestrated by T lymphocytes, and may include variable involvement of cytokines, regulatory T (Treg) cells, eosinophils, mast cells and other immune components. Helper T (Th)2 cytokines often predominate initially, followed by Th1 cytokines in more chronic phases.

HYPOTHESIS/OBJECTIVES

Pro-inflammatory and Treg cytokines have been shown to play a role in human AD, yet their importance is not clear in canine AD. Hence, this study aimed to measure the concentrations of cytokines/chemokines not traditionally associated with Th1/Th2 response.

ANIMALS

Canine AD patients (n = 27), compared to control dogs (n = 11).

METHODS AND MATERIALS

A total of 19 plasma cytokines were assayed using canine specific multiplex immuno-assays.

RESULTS

The plasma concentrations of CXC Motif Chemokine Ligand 8 (CXCL8), interleukin (IL)-7 and IL-15 cytokines were elevated in canine AD patients, compared to control dogs. In addition, stem-cell factor (SCF) concentrations were reduced in the plasma of canine AD patients compared to control dogs. Distinct cytokine profiles were found in dogs belonging to the Staffordshire breeds, a group with increased risk of AD. In particular, granulocyte-macrophage colony-stimulating factor (GM-CSF) had significantly elevated concentrations.

CONCLUSIONS AND CLINICAL RELEVANCE

Some of the plasma cytokine alterations in canine AD described here, particularly of IL-7, have not been reported previously. Monitoring these distinctive cytokine alterations could be useful for diagnosis and monitoring of canine AD in dogs.

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.

Allergen components of Dermatophagoides farinae recognised by serum immunoglobulin (Ig)E in Thai dogs with atopic dermatitis

BACKGROUND

Dermatophagoides farinae (Der f) is a common allergen in dogs with atopic dermatitis (AD). However, the relevant components of Der f require further investigation.

OBJECTIVES

We aimed to provide data on the immunoglobulin (Ig)E-binding specific components of Der f for further diagnostic and therapeutic applications.

ANIMALS

Serum samples were collected from five healthy, nine Der f-allergic atopic and seven non-Der f-allergic atopic dogs identified based on an intradermal skin test.

METHODS AND MATERIALS

We explored the component profiles of Der f extracts through 2D gel electrophoresis and IgE immunoblotting. The IgE-binding components in both groups of atopic dogs were analysed by mass spectrometry.

RESULTS

The majority of Der f-allergic atopic dogs recognised Der f Alternaria alternata allergen 10 (Der f Alt a 10), elongation factor 1-alpha (EF1-α), gelsolin-like allergen Der f 16, Der f 28 and Der f 2. Der f 3, Der f 10, Der f 20 and Der f 32 were recognised as minor allergens. Alpha-enolase, serine protease, arginine kinase and a few hypothetical proteins were recognised components in both groups of atopic dogs. Unexpectedly, Der f 15 (chitinase) was found to be a minor component.

CONCLUSIONS AND CLINICAL IMPORTANCE

Multiple IgE-binding allergens of Der f were identified in Thai atopic dogs. We propose that the specific antigen set that is bound by IgE, comprising Der f Alt a 10, EF1-α, gelsolin-like Der f 16, Der f 28 and Der f 2, could be used for future diagnostics and immunotherapy platforms.

Reproducibility of serum testing for environmental allergen-specific IgE in dogs in Europe

BACKGROUND

Serum testing for allergen-specific immunoglobulin (Ig)E is commonly employed to identify allergens used for allergen-specific immunotherapy in dogs, yet the reliability of results has been a matter of debate.

OBJECTIVE

The aim of this study was to evaluate the reproducibility of serum tests for environmental allergen-specific IgE in three European laboratories.

ANIMALS/METHODS

Serum was obtained from 33 client-owned dogs diagnosed with atopic dermatitis, divided into three aliquots and sent to the laboratories under different names. Two aliquots were sent simultaneously to one of the laboratories on the first day; the third sample was then sent to the same laboratory on the subsequent day. The laboratory for each patient was chosen according to a predetermined randomization list. The agreement between different samples from the same dog for each of the laboratories was calculated with a Cohen's Kappa test. Spearman's rank coefficients (r_sp ) as well as the coefficients of variation (CV) additionally were calculated.

RESULTS

The intra- and interassay agreements for laboratories A, B and C were 0.79 and 0.75, 0.92 and 0.90, and 0.90 and 0.85, respectively. The CVs were 18.92% and 22.95%, 14.43% and 18.79%, and 15.38% and 18.75% (respectively) and the r_sp 0.73 and 0.68, 0.95 and 0.92, and 0.82 and 0.74 (respectively).

CONCLUSION AND CLINICAL RELEVANCE

The differences in reproducibility between laboratories complicate test interpretation and underline the importance of interpreting results of serum testing for allergen-specific IgE in the context of the patient's clinical history.

Detection of Serum Allergen-Specific IgE in Atopic Dogs Tested in Northern Italy: Preliminary Study

Canine atopic dermatitis (CAD) is a pruritic allergic skin disease associated with IgE-mediated hypersensitivity. IgE is detected using Serum Allergen-Specific IgE test (SAT) in order to identify allergens. The present study aims to identify the environmental allergens in atopic dogs living in Northern Italy using SAT. The screening SAT (sSAT), using a monoclonal antibody cocktail-based ELISA to identify indoor and outdoor allergens, was performed. In all positive samples, an anti-IgE monoclonal antibody ELISA test was performed to extend panel of allergens. Out of 117 selected dogs, 69 were included in the study; 71% were positive and 29% were negative to sSAT. Among the 49 positive sSAT, 53% were positive for both indoor and outdoor, 38.8% only for indoor, and 8.2% only for outdoor allergens. This is the first study on the frequency of allergens involved in CAD in Italy using SAT. IgE hypersensitivity in atopic dogs of Northern Italy is usually associated with indoor allergens, primarily house dust mites. Among the outdoor allergens, an important role was played by Rumex acetosa. Polysensitization also commonly occurs. Therefore, since the numerous factors affect the IgE positivity in CAD, specific panels for geographical areas should be considered and re-evaluated at time intervals.

Clinical signs and diagnosis of feline atopic syndrome: detailed guidelines for a correct diagnosis

BACKGROUND

Feline atopic syndrome (FAS) describes a spectrum of hypersensitivity disorders characterised by highly diverse clinical presentations including skin, gastrointestinal and respiratory systems. Among these disorders is feline atopic skin syndrome (FASS), in which hypersensitivity is typically associated with environmental allergens, although food allergy may coexist. Involvement of other organ systems (e.g. asthma) also may occur. Because of its highly heterogeneous clinical presentation, diagnosis of FASS can be challenging.

OBJECTIVES

A subgroup of the International Committee on Allergic Diseases of Animals was tasked to summarise the most current information on the clinical presentations of FASS and to develop diagnostic guidelines.

METHODS AND MATERIALS

Online citation databases and abstracts from international meetings were searched for publications related to feline allergic conditions. These were combined with expert opinion where necessary.

RESULTS

A total of 107 publications relevant to this review were identified. Compilation of these data enabled development of a detailed description of the clinical features of FASS and development of guidelines focusing on systematic elimination of other skin conditions with similar clinical characteristics. As allergen tests are frequently used by dermatologists to support a clinical diagnosis of FASS, a brief review of these methodologies was also performed.

CONCLUSIONS AND CLINICAL IMPORTANCE

In a similar way to atopic dermatitis in dogs, FASS is a clinical diagnosis based on the presence of compatible clinical signs and exclusion of other diseases with similar clinical features. Elimination or exclusion of fleas/flea allergy, other parasites, infections and food allergy is mandatory before reaching a diagnosis of FASS.

A descriptive study of allergen-specific IgE serological tests for canine atopic dermatitis in Thailand

Background

This study describes the usefulness of allergen-specific Immunoglobulin E (IgE) serology (ASIS) for identifying allergens in dogs with atopic dermatitis. ASIS tests were conducted in 23 dogs diagnosed with atopic dermatitis for indoor allergens (yeast and mites), outdoor allergens (grass pollen, weed pollen, and tree pollen), and fleas. The relationship among positive ASIS tests were determined using Pearson’s correlation coefficient (r).

Results

Of the atopic dogs, 26.09%, 4.35%, and 47.83% had positive ASIS tests for only indoor allergens, only outdoor allergens, and both indoor and outdoor allergens, respectively. The prevalence of positive ASIS tests was highest for mites (69.57%) and did not differ between indoor and outdoor allergens by age, breed, or sex. The prevalence of positive ASIS tests for indoor allergens during the rainy season (84.21%) was significantly higher than during winter (25.00%, P-value = 0.030). The correlation coefficient of the ASIS results among the outdoor allergens indicated a strong correlation between grass and tree pollen (r = 0.840, P-value < 0.01), grass and weed pollen (r = 0.812, P-value < 0.01), and tree and weed pollen (r = 0.714, P-value < 0.01). The correlation coefficient of the ASIS results of D. farinae indicated a strong correlation with A. siro (r = 0.951, P-value < 0.01) and a moderate correlation with B. tropicalis (r = 0.656, P-value < 0.01) and T. putrescentie (r = 0.672, P-value < 0.01).

Conclusions

ASIS tests are useful in screening for multiple allergens in dogs with atopic dermatitis. Dust mites are an important source of indoor allergens and may be responsible for a higher titer of IgE antibodies against indoor allergens during the rainy season.

Comparing the results of intradermal skin tests for four dust mite allergens in dogs with atopic dermatitis in Thailand

Background and Aim

Hypersensitivity to house dust mites is a common cause of atopic dermatitis in dogs. The intradermal test (IDT) identifies allergens to be included in allergen-specific immunotherapy. Common mite allergens used for IDT include single source extracts obtained from Dermatophagoides farinae or Dermatophagoides pteronyssinus or multisource extracts from multimite species (mixed mites), as well as a combination of multimite species and proteins from feces and shed skin (house dust). The objectives of the present study were to evaluate the prevalence of mite sensitivity in dogs diagnosed with atopic dermatitis in different Thailand provinces and to determine if positive test results to mite allergens aligned.

Materials and Methods

Eighty-two dogs (median age [range]: 5 years [11 months-11 years]; 51 males and 31 females) diagnosed with atopic dermatitis underwent IDTs with four different mite-related allergens (D. farinae, D. pteronyssinus, mixed mites, and house dust). The skin reactions were reported on a scale of 0-4 and the reactions 2+ were considered clinically relevant. The relationship between IDT results from different allergens was determined using Pearson's correlation coefficient (r). Fisher's exact test was used to compare IDT results for different mite allergens as well as for dogs residing in Bangkok versus other provinces in Thailand.

Results

The prevalence (95% confidence interval [CI]) of positive IDT results for D. farinae, D. pteronyssinus, mixed mites, and house dust in dogs with atopic dermatitis was 64.63% (52.30-74.88), 58.54% (47.12-69.32), 47.56% (36.41-58.89), and 35.37% (25.12-46.70), respectively. A moderate correlation was found in IDT results between D. pteronyssinus and house dust (r=0.514), between D. pteronyssinus and D. farinae (r=0.426), and between D. farinae and mixed mites (r=0.423). The prevalence of dogs with positive IDT results for mite allergens with mono-sensitization, bi-sensitization, tri-sensitization, and quadru-sensitization did not differ significantly between dogs residing in Bangkok (11.63%, 18.60%, 25.58%, and 16.28%) and dogs residing in other provinces (12.82%, 30.77%, 35.90%, and 10.26%). The overall sensitivity (95% CI) and specificity (95% CI) of the mixed mites test associated with atopic dermatitis in dogs were 60.32% (47.20-72.40%) and 94.70% (74.00-99.90%), respectively. The overall sensitivity (95% CI) and specificity (95% CI) of the house dust test associated with atopic dermatitis in dogs were 42.90% (30.50-56.00%) and 89.50% (66.90-98.70%), respectively.

Conclusion

House dust mites are an important source of allergens for dogs with atopic dermatitis. In the present study, no significant difference in the prevalence of atopic dermatitis was found in dogs living in the urban area compared with dogs living in the countryside. Application of multisource extracts from mites for IDT revealed a higher reaction to mixed mites than that of house dust.

Detection of allergen-specific antibody-secreting cells in dogs by ELISPOT

Current laboratory tests are unable to distinguish healthy from allergic dogs. Unlike serum antibody responses, circulating antibody-secreting cells (ASC) are temporarily induced after each contact with the antigen. These ASC can be identified using ELISPOT and the observation of allergen-specific ASC might correlate with the causative allergens in dogs with an allergic dermatitis. In this study, blood was sampled from six privately-owned allergic dogs and six non-allergic laboratory beagles to determine the frequency of circulating allergen-specific ASC for common allergens. Blood IgE+, IgA + and IgG + cells were magnetically isolated to determine the number of allergen-specific ASC with ELISPOT for Dermatophagoides farinae, Dermatophagoides pteronyssinus, Alternaria alternata, birch, timothy grass, wheat, cow's milk, bovine, chicken and lamb meat. For IgA and IgG, allergen-specific spots were observed, however for IgE, no spots were detected for any of the allergens. ELISPOT could not differentiate allergic from non-allergic dogs. When the responses to the different allergens were compared, more IgA ASC for D. pteronyssinus were observed compared to some of the other allergens which was statistically significant for the non-allergic dogs and approached significance in the allergic dogs. These findings indicate that ELISPOT can be used to identify circulating allergen-specific IgA- and IgG-secreting cells. The technique did however not detect allergen-specific IgE ASC and was unable to distinguish allergic from non-allergic dogs. Only a small number of studies have studied allergen-specific IgA in dogs. The finding that dogs have higher numbers of D. pteronyssinus-specific IgA ASC points out that apart from IgE and IgG, it might be interesting to include IgA measurements for certain allergens to analyse the complete spectrum of both the protective and pro-allergic antibody responses.

Discrepancies in the bilateral intradermal test and serum tests in atopic horses

Background

In equine atopic patients intradermal testing (IDT) and immunoglobulin (Ig)E serology are used frequently. There is little evidence regarding the reproducibility of the IDT and IgE serology in horses.

Objectives

To compare the results of a simultaneously performed IDT on the left and right side of the neck in atopic horses, and to compare these results with allergen‐specific IgE serology.

Animals

Ten equine patients from a university hospital population with chronic urticaria and/or pruritus.

Methods and materials

The IDT was performed using 16 allergens and the results were evaluated after 30 min, 1, 4 and 24 h. Thirteen allergens also were analysed in duplicate with two monoclonal allergen‐specific IgE enzyme‐linked immunosorbent assays (ELISA).

Results

Good agreement (Kappa > 0.6) between left and right IDT was found only for Dermatophagoides farinae, Lepidoglyphus destructor, birch pollen mixture and perennial rye at 30 min, birch pollen mixture at 1 h, and Acarus siro and nettle and common mugwort mixture at 4 h. The bilateral comparison of the other allergens and even the same allergens at other time points showed little or no concordance between left and right IDT. The interlaboratory comparison between both ELISAs, and the comparison between the ELISAs and IDT, showed a good agreement for two of 13 allergens: D. farinae and Dermatophagoides pteronyssinus.

Conclusions and clinical importance

Based on these preliminary data, IDT and IgE serological test results should be interpreted with great care and further studies are needed to indicate the clinical relevance of these findings.

A Pilot Study on the Safety of a Novel Antioxidant Nanoparticle Delivery System and Its Indirect Effects on Cytokine Levels in Four Dogs

Acute spinal cord injury consists of a primary, traumatic event followed by a cascade of secondary events resulting in ongoing cell damage and death. There is great interest in prevention of these secondary effects to reduce permanent long-term neurologic deficits. One such target includes reactive oxygen species released following injury, which can be enzymatically converted into less harmful molecules by superoxide dismutase and catalase. Canine intervertebral disc herniation has been suggested as a naturally occurring model for acute spinal cord injury and its secondary effects in people. The aims of this study were to test the safety of a novel antioxidant delivery system in four healthy dogs and to indirectly test effect of delivery via cytokine measurement. All dogs experienced adverse events to some degree, with two experiencing adverse events considered to be severe. The clinical signs, including combinations of bradycardia, hypotension, hypersalivation, pale gums, and involuntary urination, were consistent with complement activation-related pseudoallergy (CARPA). CARPA is a well-known phenomenon that has been reported to occur with nanoparticle-based drug delivery, among other documented causes. Two dogs also had mild to moderate changes in their blood cell count and chemistry, including elevated alanine transferase, and thrombocytopenia, which both returned to normal by day 7 post-administration. Cytokine levels trended downwards over the first 3 days, but many were elevated at measurement on day 7. Intradermal testing suggested catalase as a potential cause for reactions. No long-term clinical signs were observed, and necropsy results revealed no concerning pathology. Additional evaluation of this product, including further characterization of reactions to catalase containing components, dose-escalation, and desensitization should be performed before evaluation in clinically affected dogs.

Serum allergen-specific IgE reactivity: is there an association with clinical severity and airway eosinophilia in asthmatic cats?

OBJECTIVES

The aim of this study was to evaluate the results of serum allergen-specific IgE testing in cats with a clinical diagnosis of asthma and to determine if the number of allergens with positive IgE reactivity and magnitude of positive IgE responses would be associated with the severity of clinical signs or airway eosinophilia.

METHODS

Medical records from 2008 to 2018 were retrospectively reviewed. Inclusion required a diagnosis of feline asthma based on consistent clinicopathologic features and bronchoalveolar lavage (BAL) cytology with >10% eosinophils; additionally, cats needed to have the results of serum allergen-specific IgE tests.

RESULTS

Eighteen cases satisfied the inclusion criteria. Median age was 5 years and the most common presenting clinical sign was cough (n = 10/18). Most cats lived exclusively indoors (n = 13/18). The median percentage of BAL eosinophils was 47%. Serum allergen-specific IgE testing supported an underlying allergic etiology in 14/18 (78%) cats, with all but one having polysensitization. The severity of clinical signs and magnitude of airway eosinophilia did not correlate with the degree of positive IgE reactivity.

CONCLUSIONS AND RELEVANCE

This study identified a strong association between the identification of allergen-specific IgE and cats with asthma, and the majority of these cats were polysensitized. However, larger numbers of allergens with positive IgE reactivity or magnitude of IgE reactivity were not significantly associated with clinical severity or airway eosinophilia. Knowledge of positive allergen-specific IgE results could guide allergen avoidance, regardless of the magnitude of IgE reactivity.

Effect of diphenhydramine and cetirizine on immediate and late-phase cutaneous allergic reactions in healthy dogs: a randomized, double-blinded crossover study

BACKGROUND

Currently, there is insufficient evidence to confirm oral diphenhydramine (DPH) efficacy to prevent mast cell degranulation and histamine release in dogs.

HYPOTHESIS/OBJECTIVE

To determine and compare the effects oral of DPH and cetirizine on the immediate- and late-phase cutaneous allergic reactions in healthy dogs.

ANIMALS

Twelve healthy laboratory beagle dogs.

METHODS AND MATERIALS

The study was designed as a randomized, double-blinded crossover study in which each dog served as its own control; twice-daily oral DPH (2.2 mg/kg) or cetirizine (2 mg/kg) were given for six days with a two week washout period. Intradermal injections of histamine, compound 48/80 (positive control) and saline (negative control) were performed on the right thorax 10 days before drug administration (baseline), during oral antihistamine administration on Day 6 and 10 days after last medication dosage. Global wheal scores (GWS) at 20 min and late-phase reactions (LPR) at 6 h post-injection were evaluated by an investigator blinded to the drug and the interventions.

RESULTS

Treatment with cetirizine significantly reduced histamine and compound 48/80 GWS and LPR compared to baseline; there was no significant difference for DPH. In all dogs, oral DPH and cetirizine reached plasma concentrations considered therapeutic in people. No adverse effect or behavioural changes were observed during the study.

CONCLUSION AND CLINICAL SIGNIFICANCE

In conclusion, oral cetirizine was effective in preventing cutaneous allergic reactions without any obvious adverse effects in dogs. Oral DPH failed to show an inhibitory effect despite attaining plasma drug concentrations that are considered effective in people.

Evaluation of Skin Prick-Test Reactions for Allergic Sensitization in Dogs With Clinical Symptoms Compatible With Atopic Dermatitis. A Pilot Study

Skin prick-test is the first choice for the detection of type I hypersensitivity in human atopic dermatitis. Canine atopic dermatitis resembles several symptoms of the disease in the human counterpart. In canine atopic dermatitis, intradermal testing is the test of choice, and there are few reports on the use of skin prick test (SPT) in dogs. The purpose of this study was to evaluate SPT reactions in atopic dogs and a healthy control group to 11 environmental allergens. Eleven glycerinated allergens were applied on the left lateral thorax of nine atopic dogs and nine healthy dogs. The skin was pricked with a feather lancet and evaluated for the positive percutaneous reaction at 5, 10, 15, and 20 min after the application of the allergens. Data were analyzed by the Shapiro-Wilk test to test for normal distribution. Data that did not meet normality were analyzed by a one-sided Wilcoxon ranked sum test with a p-value of 0.05. Six out of 9 atopic dogs tested positive for at least one of the allergens tested. None of the dogs in the control group showed a positive reaction to the allergens included in the test. Blomia tropicalis, Dermatophagoides farine, and Dermatophagoides pteronyssinus exhibited the highest reaction rate among the group of atopic dogs. There was not a statistical difference in the histamine reaction (positive control) between both groups. In this set of dogs, the test exhibited a 100% specificity and a sensitivity of 66%. The use of skin prick-test in the detection of causative allergens of human atopic dermatitis has proved to be a sensitive and specific tool frequently used by human allergists. Due to the number of similarities in canine and human atopic dermatitis, this could be a valuable tool that needs intensive research in veterinary medicine. The published research so far correlates to the results obtained in this investigation. However, future studies evaluating the concordance between in vitro specific IgE antibody assays and SPT must be carried out simultaneously to validate the test.

Prevalence of positive reactions in intradermal and IgE serological allergy tests in dogs from South Australia, and the subsequent outcome of allergen-specific immunotherapy

OBJECTIVE

To determine the prevalence of positive allergen reactions in intradermal and IgE serological tests in dogs presenting to a dermatology referral centre in South Australia and the clinical efficacy of subsequent allergen-specific immunotherapy.

DESIGN

Retrospective study.

METHODS

Results from 108 intradermal allergy tests, 25 IgE serological assays and immunotherapy outcomes in 37 dogs were retrospectively analysed. Immunotherapy outcomes were determined as excellent, good, modest or failure using a global assessment of efficacy matrix which incorporated pruritus scores, lesion severity, medication requirements, and owner and clinician opinion.

RESULTS

The most common positive reactions in intradermal allergy tests were Red clover (59%), Dermatophagoides farinae (29%), Tyrophagus putrescentiae (28%), Yellow dock (25%) and Malassezia pachydermatis (24%). In the IgE serological tests, Yorkshire fog grass (40%), Yellow dock (36%), Kentucky bluegrass (36%) and T. putrescentiae (36%) were the most commonly reported positive results. The outcome of allergen-specific immunotherapy was judged to be excellent in 20% of dogs, good in 15%, modest in 18% and a failure in 47%.

CONCLUSION

As has been reported in other geographical areas, environmental mites and plant pollens frequently gave positive reactions in allergy tests in South Australia. However, the prevalence of individual allergen reactions differed between intradermal and IgE serological tests, with M. pachydermatis being identified as a common cause of hypersensitivity in intradermal tests but not in IgE serological assays. Immunotherapy was judged to be a beneficial treatment in 35% of dogs but was essentially unsuccessful in 65%.

Intradermal reactivity to two concentrations of pollen extracts in atopic dogs

BACKGROUND

Intradermal test (IDT) is used widely for determination of allergens to include in allergen-specific immunotherapy (AIT). The optimal concentration of allergen solutions used for testing has not been established in atopic dogs. Inadequate concentrations could lead to falsely negative test results and lack of inclusion of important allergens in AIT.

HYPOTHESIS/OBJECTIVES

To compare IDT reactivity to two concentrations of five pollen extracts and determine the effect on ASIT prescription.

ANIMALS

Atopic dogs (n = 67) had IDT results including all of the allergens of interest.

METHODS AND MATERIALS

Medical records from a veterinary teaching hospital were reviewed for all atopic dogs undergoing IDT over a three year period. In addition to the hospital's standard IDT concentration of 1,000 PNU/mL for pollen allergens, five pollen allergens of higher concentration (3,000-8,000 PNU/mL) had been added at the beginning of that period. The IDT scores for the standard test concentration of each of the five allergens were compared to the scores for the higher concentration.

RESULTS

Positive reactions occurred much more commonly to the higher test concentration for each of the paired allergens (P < 0.05, chi-square). The AIT formulation was different in 58% of the dogs from what it would have been without the higher concentration allergens.

CONCLUSIONS AND CLINICAL IMPORTANCE

The current standard IDT concentration of 1,000 PNU/mL for pollen allergens is likely too low, possibly resulting in inaccurate AIT formulations. This might explain treatment failures and the incorrect diagnosis of atopic-like dermatitis. Further work is needed to establish optimal allergen test concentrations.

Atopic dermatitis in cats and dogs: a difficult disease for animals and owners

The purpose of this review article is to give an overview of atopic dermatitis in companion animals and of recent developments including knowledge on immunological background, novel treatment options and difficulties in disease management. The prevalence of hypersensitivities seems to be increasing. The pathogenetic mechanisms are not fully understood, yet multiple gene abnormalities and altered immunological processes are involved. In dogs and cats, the diagnosis of atopic dermatitis is based on history, clinical examination and exclusion of other differential diagnoses. Intradermal testing or testing for serum allergen-specific Immunoglobulin E is only used to identify allergens for inclusion in the extract for allergen immunotherapy. Symptomatic therapy includes glucocorticoids, ciclosporin, essential fatty acids and antihistamines. A selective janus kinase 1 inhibitor and a caninized monoclonal interleukin-31 antibody are the newest options for symptomatic treatment, although longterm effects still need to be assessed. The chronic and often severe nature of the disease, the costly diagnostic workup, frequent clinical flares and lifelong treatment are challenging for owners, pets and veterinarians. Patience and excellent communication skills are needed to achieve a good owner compliance and satisfactory clinical outcome for the animal.

A study to evaluate the primary causes associated with Pseudomonas otitis in 60 dogs

OBJECTIVES

To evaluate the primary causes, age of onset and time from diagnosis of otitis to development of Pseudomonas otitis in each case.

MATERIALS AND METHODS

Data from clinical records of 60 dogs were extracted to address the study objectives. Pseudomonas otitis was diagnosed by clinical signs and positive culture.

RESULTS

In total, 57 purebred dogs and three crossbreed dogs were included: 32 dogs had unilateral and 28 bilateral disease. Underlying primary causes of otitis were allergy (42), masses (8), endocrine disease (7) and autoimmune disease (3). The mean age of onset of otitis (and subsequent time to development of Pseudomonas otitis) in dogs with allergic otitis was 40 months (28 months), with endocrine disease was 56 months (19 months) and masses 99 months (10 months).

CLINICAL SIGNIFICANCE

The most common primary causes of otitis in dogs with Pseudomonas infections are, in decreasing frequency: allergies, masses, endocrine disease and autoimmune disease. Secondary infections with Pseudomonas developed more quickly if there was a mass or autoimmune disease, as compared with allergies and endocrinopathies.

Determination of irritant threshold concentrations of multiple tree, grass, weed and mould allergens for intradermal testing of horses residing in the southern USA

BACKGROUND

Appropriate allergen threshold concentrations (TCs) for intradermal testing (IDT) have not been established in horses for many pollen and mould allergens.

OBJECTIVES

To determine the TCs in non-allergic horses and describe the frequency of late phase reactions for 26 allergens, including trees, grasses, weeds and moulds in horses residing in the southern Unites States.

ANIMALS

Twenty four clinically normal horses in the southern United States.

METHODS

Threshold concentrations for different allergens were determined using IDT subjective measurements at 30 minutes. Delayed reactions were evaluated at 4 and 24 h.

RESULTS

Threshold concentrations (all PNU/mL) were established for eight tree allergens (black willow 1,000, box elder 1,000, live oak 1,000, pecan 2,000, white ash 4,000, red oak 4,000, red mulberry 2,000 and green ash 2,000); two grass allergens (Johnson grass 250 PNU/mL and Kentucky blue grass 500 PNU/mL); two weeds (carelessweed 1,000 PNU/mL, great ragweed 500 PNU/mL) and one mould (Curvularia 8,000 PNU/mL). The TC was not determined due to excessive reactivity at the lowest concentration tested (1,000 PNU/mL) for bahia and perennial rye grass. Eleven other allergens did not meet the criteria to establish a TC when evaluated at 30 min due to lack of positive reactions. Multiple allergens caused positive reactions in ≥10% of horses at 4 h. Reactions at 24 h were rare with the exception of one horse.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study identified intradermal TC for multiple pollen and mould allergens in horses. These values may prove useful for optimizing allergen concentrations for IDT of allergic horses.

Hypersensitivity to Culicoides midges causing seasonal dermatitis in sheep

Culicoides midges are important as vectors of disease, as an irritant with severe effects on human outdoor activities in certain areas and as the cause of insect bite hypersensitivity in domestic animals (most notably horses). Here we report, for the first time, the confirmation of ovine hypersensitivity to Culicoides midges in Hebridean sheep suffering from seasonal allergic skin disease using intradermal allergen testing. The affected sheep formed 40% of the adults in the small flock, and this indication of a potentially high prevalence of a condition with welfare implications is of concern.

Influence of glucocorticoids on a time-of-day-dependent variation in intradermal reactivity to histamine in dogs

The objectives of this study were to determine daily variation in intradermal reactivity to histamine in dogs and to evaluate a potential influence of glucocorticoids on reactivity. Wheal sizes formed after intradermal injections of histamine were measured every 6 h during a single 24 h period in six healthy dogs. To determine whether glucocorticoids were implicated in daily variation, intradermal reactivity to histamine was evaluated at 9:00 h and at 21:00 h during a single day in dogs that received oral prednisolone (a synthetic glucocorticoid) or oral trilostane (an inhibitor of endogenous glucocorticoid synthesis). Finally, the time required for the histamine reaction to diminish after an intravenous injection of hydrocortisone was also assessed. A significant time-of-day-dependent variation in intradermal reactivity to histamine was detected in dogs, with a larger wheal size observed at 9:00 h than at 21:00 h. Administration of prednisolone or trilostane disrupted this variation. Intradermal reactivity to histamine was significantly reduced 6 h after an intravenous injection of hydrocortisone. These results suggest that glucocorticoid secretion from the adrenal glands could be involved in the regulation of daily variation in histamine-mediated reactions in dogs.

Cutaneous Adverse Drug Reactions in Dogs Treated with Antiepileptic Drugs

Epilepsy is one of the most common neurologic disorders in dogs and life-long treatment with antiepileptic drugs (AED) is frequently required. Adverse events of AED targeting the skin are only rarely reported in veterinary medicine and the true incidence and spectrum of cutaneous reactions in epileptic dogs remains unknown. In this study, we hypothesized that cutaneous reactions commonly occur in epileptic dogs and are related to AED treatment. A retrospective case review of 185 dogs treated for epilepsy identified 20.0% with simultaneous appearance of dermatologic signs. In a subsequent prospective case investigation (n = 137), we identified newly appearing or distinct worsening of skin lesions following initiation of AED therapy in 10.9% of dogs treated for epilepsy (95% CI 6.8–17.7%). Cutaneous lesions were classified as probably drug-induced in 40.0% of these cases. Patch testing and intradermal testing were further investigated as potential diagnostic methods to confirm AED hypersensitivity. They were of high specificity but sensitivity and positive predictive value appeared inappropriate to recommend their routine use in clinical practice.

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.

Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification

BACKGROUND

Canine atopic dermatitis (AD) is a common, genetically predisposed, inflammatory and pruritic skin disease. The variation in clinical presentations, due to genetic factors, extent of the lesions, stage of the disease, secondary infections, as well as resemblance to other non-atopic related skin diseases, can complicate a diagnosis of canine AD. A sub-group of the International Committee for Allergic Diseases in Animals (ICADA) was tasked with the development of a set of practical guidelines that can be used to assist practitioners and researchers in the diagnosis of canine AD. Online citation databases and abstracts from international meetings were searched for publications related to the topic, and combined with expert opinion where necessary. The final set of guidelines was approved by the entire ICADA committee.

RESULTS

A total of 81 publications relevant for this review were identified. The guidelines generated focus on three aspects of the diagnostic approach: 1. Ruling out of other skin conditions with clinical signs resembling, or overlapping with canine AD. 2. Detailed interpretation of the historical and clinical features of patients affected by canine AD. 3. Allergy testing by intradermal versus allergen-specific IgE serum testing.

CONCLUSIONS

The diagnosis of canine AD is based on meeting clinical criteria and ruling out other possible causes with similar clinical signs. Flea combing, skin scraping and cytology should be performed, where necessary, as part of a thorough work-up. Elimination diet trials are required for patients with perennial pruritus and/or concurrent gastrointestinal signs. Once a clinical diagnosis of canine AD is made, allergy testing can be performed to identify potential causative allergens for allergen-specific immunotherapy.

Proficiency monitoring of monoclonal antibody cocktail–based enzyme-linked immunosorbent assay for detection of allergen-specific immunoglobulin E in dogs

The purpose of our study was to document the continued comparative proficiency of different laboratories that perform a monoclonal antibody–based enzyme-linked immunosorbent assay (macELISA) for detection of allergen-specific immunoglobulin (Ig)E in dogs. Replicate samples of 18 different sera pools were independently evaluated in a single blinded fashion by each of 16 different operators functioning in 10 different laboratories. The average intra-assay variance among reactive assay calibrators in all laboratories was 6.0% (range: 2.7–16.1%), while the average intralaboratory interassay variance was 7.5% (range: 3.9–10.9%). The overall interassay interlaboratory variance was consistent among laboratories and averaged 11.4% (range: 8.5–12.5%). All laboratories yielded similar profiles and magnitudes of responses for replicate unknown samples; dose response profiles observed in each of the laboratories were indistinguishable. Considering the positive or negative results, interassay interlaboratory concordance of results exceeded 90%. Correlation of optical density values between and among all laboratories was strong ( r > 0.9, P < 0.001). Collectively, the results demonstrated that the macELISA for measuring allergen-specific canine IgE is reproducible, and documents that consistency of results can be achieved not only in an individual laboratory by differing operators but also among laboratories using the same monoclonal-based ELISA.

Equine intradermal test threshold concentrations for house dust mite and storage mite allergens and identification of stable acari fauna

BACKGROUND

House dust mite (HDM) and storage mite (SM) stable fauna and their associated equine intradermal test (IDT) threshold concentrations (TCs) for the midwestern region of the USA are unknown.

HYPOTHESIS/OBJECTIVES

To determine IDT TCs and serum IgE concentrations for two HDM and three SM species in clinically normal horses over two seasons, and to identify the mite taxa and habitats in a stable.

ANIMALS

Thirty-eight clinically normal horses.

METHODS

Threshold concentrations for HDMs and SMs were determined using IDT subjective measurements and a statistical model. An enzyme-linked immunosorbent assay was used to quantify serum IgE concentrations for the same mite species. A modified flotation method was used to identify morphologically HDMs and SMs.

RESULTS

Subjective IDT TCs were as follows: 1:80,000 w/v for Dermatophagoides farinae in both seasons; 1:80,000 w/v in spring and 1:160,000 w/v in late summer for Dermatophagoides pteronyssinus; 1:40,000 w/v in spring and 1:20,000 w/v in late summer for Acarus siro; 1:20,000 w/v for Lepidoglyphus destructor in both seasons; and 1:20,000 w/v in spring and 1:10,000 w/v in late summer for Tyrophagus putrescentiae. Statistically significant associations for increased serum IgE and a positive IDT reaction were evident for D. farinae in the spring and D. pteronyssinus in both seasons. One mite from all four genera specific to this study was identified; however,two HDM and A. siro species were not detected.Conclusions and clinical importance – This study established HDM and SM IDT dilution concentrations for the horses in this region. Exposure to diverse acaridae fauna may contribute to the pathogenesis of equine allergic disease.

Characterisation of dog sensitisation to grass pollen in western France from 1999 to 2010

Very few studies have investigated the seasonal aspect of grass pollen sensitisation or its evolution in the allergic canine population. The aim of this study was to evaluate both these aspects. A study of canine grass pollen sensitisation was performed throughout the statistical analysis of 261 intradermal skin testings (IDT=25 allergens tested on average) performed from January 1999 to December 2010. IDTs were performed on dogs with pruritic allergic skin disease. χ(2) Tests were used for statistical analysis. Two hundred and thirteen dogs (81.6 per cent) were sensitised to at least one allergen, and 56 (21.5 per cent) to at least one grass pollen. No increase in the rate of positive IDT was recorded over three periods: 1999-2002, 2003-2006 and 2007-2010. No statistical correlation was detected between sex, age or birth month and grass sensitisation. Moreover, no link was found between the season in which the IDT was performed and sensitisation, indicating that there is no seasonality to the sensitisation. However, considering the grasses tested over these three periods (grass mix and rye grass), a clear and significant increase in the percentage of dogs sensitised to grass pollen was observed between 1999-2002 and 2007-2010 (14.4 per cent and 27.7 per cent, respectively). The possible reasons for this sensitisation increase of dogs to grass pollen are discussed.

Cross-reaction and co-sensitization among related and unrelated allergens in canine intradermal tests

BACKGROUND

Intradermal tests are used to identify allergens for avoidance and immunotherapy in atopic dogs.

HYPOTHESIS/OBJECTIVES

To evaluate cross-reaction or co-sensitization among 53 intradermal test allergens.

ANIMALS

Six hundred and fifty-one client-owned dogs with atopic dermatitis.

METHODS

Intradermal tests were performed with 53 house dust/storage mite, epidermal, insect, tree, weed and grass pollen and mould allergens. Pairwise comparisons were used to calculate the odds ratios (ORs), 95% confidence intervals (CIs) and statistical significance for the results of each allergen pair, with significance at P < 0.0006 (Holm-Bonferroni correction to reduce the false-detection rate).

RESULTS

Apart from cotton, cockroach, red clover, grain smut and Penicillium, the results for the allergens within each group were statistically associated [ORs from 4.7 (CI 2.5-8.9) to 1229.4 (CI 166.5-1795.1); P = 0.0005 to P < 0.0001]. Excluding red clover and cotton, 94% of results between tree, weed and grass pollens were also statistically associated [ORs from 8.3 (CI 3.6-24.7) to 117 (CI 29.1-341); P = 0.0005 to P < 0.0001]. In contrast, few allergens from unrelated groups were statistically associated [ORs from 0.12 (CI 0.03-1.1) to 27.7 (CI 0.2-93); P = 1.0 to P < 0.0001]. The mean (SD) of the log e transformed ORs for the related and statistically associated allergens [5.3 (1.3)] was significantly greater than those for related but nonstatistically associated [1.7 (1.6)] or unrelated allergens [1.4 (1.4); P < 0.0001].

CONCLUSIONS AND CLINICAL IMPORTANCE

This suggests that there is cross-reaction or co-sensitization between related allergens. This could have implications for allergen selection in testing and immunotherapy, but further studies are required to differentiate cross-reaction from co-sensitization.

Intra and inter-laboratory reproducibility of a monoclonal antibody cocktail based ELISA for detection of allergen specific IgE in dogs: proficiency monitoring of macELISA in six laboratories

The purpose of this study was to evaluate the reproducibility of results yielded using a monoclonal antibody based ELISA for detection of allergen specific IgE when run in six separate affiliated laboratories. On two separate occasions, duplicate samples of 15 different sera pools were independently evaluated by each laboratory in a single blinded fashion. The average intra-assay variance among reactive assay calibrators in all laboratories was 6.2% (range 2.6-18.2%), while the average intra-laboratory inter-assay variance was 12.1% (range 8.0-17.1%). The overall inter-assay inter-laboratory variance was consistent among laboratories and averaged 15.6% (range 15.1-16.6%). All laboratories yielded similar profiles and magnitudes of responses for replicate unknown samples; dose-response profiles observed in each of the laboratories were indistinguishable. Considering positive/negative results, inter-assay inter-laboratory concordance of results exceeded 95%. Correlation of OD values between and among all laboratories was strong (r>0.9, p<0.001). Correlation of OD values between the two separate evaluations was also high for all allergens except olive, which was attributed to lot-to-lot differences of allergen coated wells. Collectively, the results demonstrated that the monoclonal antibody based ELISA for measuring allergen specific canine IgE is reproducible, and documents that consistency of results can be achieved not only in an individual laboratory, but between laboratories using the same monoclonal-based ELISA.

Comparison of subjective and objective intradermal allergy test scoring methods in dogs with atopic dermatitis

An intradermal allergy test (IDT) is an important diagnostic tool for identifying offending allergens in canine atopic dermatitis. No standardized method of scoring an IDT has been described. The purpose of this study was to determine whether there is a correlation between a conventional, subjective IDT scoring method based on perceived wheal diameter, erythema, and turgor (0-4+) and an objective scoring method based on measuring wheal diameter alone. Thirty-four atopic dogs were skin tested with 68 different allergens. All skin tests were performed according to standard procedures, and any IDT score ≥2+ was considered clinically significant. When the subjective IDT scores were compared with the objective IDT scores in all dogs, there was a moderate level of correlation overall (r=0.457; P <0.0001). The highest level of agreement between subjective and objective scores was noted with the reactions assigned subjective scores of "0" and "2+." Overall, there was a slight level of agreement between subjective and objective scores based on clinical significance (i.e., subjective scores ≥2+; κ=0.20; P <0.0001). In conclusion, the authors believe that the objective scoring method used in this study may provide a point of reference for inexperienced individuals (dermatology residents, veterinarians, technicians) when learning to grade an IDT.

The lipid alterations in the stratum corneum of dogs with atopic dermatitis are alleviated by topical application of a sphingolipid-containing emulsion

BACKGROUND

Atopic dermatitis (AD) results from an altered skin barrier associated with defects in the lipid composition of the skin. Dogs with AD present similar clinical symptoms to humans, and may be a useful model for investigations into AD.

AIM

To analyse the changes occurring in the lipids of the stratum corneum (SC) of dogs with AE after 3 weeks of topical treatment with an emulsion containing ceramides, free fatty acids (FFAs) and cholesterol (skin lipid complex; SLC).

METHODS

Nonlesional SC was collected by tape stripping from control and treated areas. Free and protein-bound lipids were purified, and the various classes were isolated by column chromatography, analysed by thin-layer chromatography and assayed.

RESULTS

Ceramides, FFA and cholesterol were all found to be lower in the skin of untreated dogs with AD than in normal dogs, and the topical treatment resulted in significantly increased values for ceramides. Conversely, only trace amounts of glucosylceramides were present in normal SC, but a high concentration (27 μg per mg protein) was detected in canine atopic SC, which disappeared after treatment with SLC. There was a heterogeneous distribution of all of the lipids in the different layers of canine atopic SC, which was more pronounced for protein-bound than for free lipids. Following topical treatment, the protein-bound lipid content normalized.

CONCLUSIONS

Topical treatment with SLC resulted in a significant improvement of the lipid biosynthesis of keratinocytes in atopic dogs, thereby potentially enabling the formation of a tighter epidermal barrier.