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Background: Dogs with atopic dermatitis are often immunoglobulin (Ig)E-sensitised to Dermatophagoides farinae (Df) house dust mites, yet limited data exist on the sensitisation rates to the individual Df allergens, Der f 2 and Zen 1., Objectives: To determine the IgE sensitisation rates to Df, Der f 2 and Zen 1 in atopic dogs from geographically diverse countries., Animals: Serum was collected from 32 laboratory dogs in Japan, and 837 atopic dogs from 11 countries from five continents: Asia (Japan, Thailand, Taiwan), Europe (Italy, Latvia, the Netherlands, UK), North America (USA), South America (Argentina, Brazil) and Africa (South Africa)., Methods and Materials: We determined Df-, Der f 2- and Zen 1-specific IgE levels by ELISA. Correlations between the IgE values for these three allergens were calculated., Results: The IgE seropositivity rates for Df varied between 74% (Argentina) and 100% (the Netherlands, Thailand, South Africa), those for Der f 2 between 12% (Argentina) and 88% (South Africa), and for Zen 1 between 70% (Argentina) and 100% (the Netherlands). Apart from the especially low seropositivity rate for Der f 2-specific IgE in Argentina, the percentage of IgE sensitisation varied little between countries. There was significant correlation between the IgE levels to these three allergens which was highest between Df and Zen 1, and lowest between Zen 1 and Der f 2., Conclusions and Clinical Relevance: The IgE sensitisation to Df is geographically widespread. Der f 2 and Zen 1 are major allergens for dogs in almost all countries where this was evaluated., (© 2021 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of ESVD and ACVD.)

Background: To optimise the interleukin (IL)-31-blocking therapy in atopic dermatitis (AD), an understanding of the chronology in the expression of IL-31 and its receptor (IL-31RA) is needed., Hypothesis/objectives: (i) To assess the chronological expression of IL-31 in canine AD skin lesions, (ii) to compare it with serum IL-31 levels and macroscopic skin lesion scores, and (iii) to determine the identity of IL-31- and IL-31RA-positive cells., Animals: Four atopic dogs sensitised to house dust mites., Methods and Materials: Skin and blood samples were obtained 0 h, 24 h, 48 and 96 h after allergen provocation. IL-31 and IL-31RA single-staining immunofluorescence (IF), as well as IL-31/CD3, IL-31/CD4 and IL-31RA/β3-tubulin double-staining IF were performed. The IL-31-positive cells were counted subjectively., Results: The peak IL-31 expression for three of four dogs occurred 24 h or 48 h postchallenge; it started to decrease at 96 h. There was no significant correlation between the IL-31 expression scores and the serum IL-31 concentrations or the macroscopic skin lesion scores (P = 0.35 and P = 0.36, respectively). The majority of IL-31-positive cells were positive for CD3 (range 91-100%) and CD4 (range 63-100%), indicating that they were helper T (Th) cells. Unexpectedly, sebaceous glands were strongly immunolabelled with IL-31; the extinction of this positivity after immunoabsorption with IL-31 further supported the validity of this immunostaining. The IL-31RA was visualised on keratinocytes and a small proportion of dermal nerves., Conclusions and Clinical Importance: The early and transient production of IL-31 by Th cells supports the concept of using IL-31 inhibiting strategies as a proactive therapy to prevent flares of AD skin lesions., (© 2021 ESVD and ACVD.)

Background: Feline diseases of possible allergic origin with similar clinical phenotypes can have a varied underlying pathogenesis. Clinical phenotype, precise aetiology and underlying immunopathogenesis all need to be considered if advances in this neglected area of dermatology are to be made., Objectives: To document the status of research into the immunopathogenesis of the diseases that fall within the spectrum of the feline atopic syndrome (FAS ), to summarize the conclusions, identify the limitations and recommend future research directions., Methods and Materials: A search of the literature was undertaken. The strengths and validity of the data and the contributions to our current understanding of the immunopathogenesis were analysed. Skin diseases of presumed allergic aetiology and asthma were assessed separately, as was the role of antibodies, cells and cytokines in each., Results: The research varied in its quality and its impact often was limited by a failure to employ strict criteria in case selection. This reflected the difficulties of skin reaction patterns associated with a number of inciting causes. Research into feline asthma was handicapped by the difficulties of investigating clinical material, and much of the useful information was derived from experimental models., Conclusions and Clinical Importance: The evidence reviewed was supportive of a role for immunoglobulin (Ig)E in the pathogenesis of both feline atopic skin syndrome (FASS) and asthma, albeit not strongly so. The inflammation noted in both FASS and asthma is accompanied by eosinophils and lymphocytes, and these findings, together with the cytokine expression, are suggestive in some (not all) cats of T-helper type 2 immune dysregulation., (© 2021 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the European Society of Veterinary Dermatology and the American College of Veterinary Dermatology.)

Background: Feline allergic diseases present as challenging problems for clinicians, not least because of the number of reaction patterns of the feline skin, none of which are specific for allergy. Furthermore, there is some controversy over the nomenclature that should be used in their description., Objectives: To review the literature, assess the status of knowledge of the topic and the extent to which these diseases could be categorized as atopic in nature, and make recommendations concerning nomenclature., Methods: Atopic diseases in humans and cats were researched. A comparison then was made of the essential features in the two species., Results: There were sufficient similarities between human atopic diseases and the manifestations of feline diseases of presumed allergic aetiology to justify the use of "atopic" to describe some of the feline conditions affecting the skin, respiratory and gastrointestinal tract. However, none of the allergic skin diseases showed features consistent with atopic dermatitis as described in man and the dog., Conclusions and Clinical Importance: The term "Feline Atopic Syndrome" (FAS) is proposed to encompass allergic diseases of the skin, gastrointestinal tract and respiratory tract, and "Feline atopic skin syndrome" (FASS) proposed to describe allergic skin disease associated with environmental allergies. We are not aware of any adverse food reactions in cats that are attributable to causes other than immunological reactions against the food itself. We therefore propose an aetiological definition of "Food Allergy" (FA) to describe such cases., (© 2021 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the European Society of Veterinary Dermatology and the American College of Veterinary Dermatology.)

Cyclosporine is used to treat immune-mediated and allergic conditions and to prevent transplant rejection. To determine the prevalence of bacterial infections during cyclosporine therapy in dogs, 2 databases were searched and 14 articles reporting usable data were identified. In 828 dogs with atopic dermatitis receiving anti-allergic dosages of cyclosporine, the prevalence of bacterial infections was 11%; these occurred most often in the integument and urinary systems and not in multiple systems. In 95 dogs receiving cyclosporine at higher dosages for other conditions, the prevalence of bacterial infection was 17%, and these infections occurred most often in the gastrointestinal, urinary, and respiratory systems, often occurring at more than one body site. The prevalence of bacterial infections in atopic dogs treated with cyclosporine is low and occurs most often in the skin. When given for immunosuppression, the prevalence of bacterial infections is higher and can affect one or more body systems., Competing Interests: Conflict of interest: Dr. Olivry declared having been a consultant, received lecturing honoraria and research funding from Novartis Animal Health or Elanco., (Copyright and/or publishing rights held by the Canadian Veterinary Medical Association.)

Background: Canine atopic dermatitis (cAD) is a common allergic skin disease that is known to affect individuals early in life; the natural history of its initial development has not been documented. Some breeds such as West Highland white terriers (WHWTs) are highly predisposed to cAD., Objectives: To follow 100 WHWT puppies during their first three years and to record the onset of clinical signs of cAD., Animals: One hundred and eight puppies from 29 litters were included and 90 were followed for three years., Methods and Materials: Puppies were examined initially while with their breeders. After adoption, the owners were contacted twice each year and dogs were examined by veterinarians if signs compatible with cAD were detected; diagnosis of cAD was by two different definitions. The onset, location of the clinical signs and severity of cAD, as well as co-morbidities were recorded., Results: The prevalence of cAD in the cohort was 52%. Most affected dogs (60%) developed signs of cAD during their first year of life and males were over-represented. The location of clinical signs mirrored those of previous descriptions. The severity of cAD was mild in 36% and severe in 13% of affected WHWTs. Dogs with cAD often exhibited other atopic diseases, but only gastro-intestinal signs were significantly different between WHWTs with and without cAD. Adverse reaction to foods was diagnosed in 24% of dogs., Conclusion and Clinical Importance: This longitudinal study of puppies from a predisposed breed sheds new light on the early development of cAD in WHWTs., (© 2019 the European Society of Veterinary Dermatology and the American College of Veterinary Dermatology.)

Background: Food allergy is a possible cause of atopic dermatitis (AD) in dogs; it is typically diagnosed following an eight-week elimination diet trial (EDT) and a provocation with the original diet. This lengthy procedure is difficult for owners and its interpretation may be unclear., Hypothesis/objectives: To test the effect of prednisolone used in the first weeks of an EDT in order to reduce the total time period for diagnosis. The goal was to perform food challenges earlier than after the traditionally recommended eight weeks., Animals: Fifty-three dogs with AD were included in the study., Methods and Materials: All dogs were fed a commercially available extensively hydrolyzed protein-based commercial pet food and treated with prednisolone for at least two weeks to control pruritus and inflammation. Dogs were challenged two weeks after prednisolone finished, provided that no flare had occurred. Dogs with relapsing signs were fed the hydrolyzate for at least eight weeks with or without further prednisolone treatment., Results: Ten of 53 dogs (19%) had no relapse after two weeks off prednisolone: they were subsequently challenged with their regular food, had a relapse of signs and were diagnosed with a food-induced AD within four to six weeks of starting the EDT. In the other dogs, signs remained uncontrolled without prednisolone or relapsed rapidly after its discontinuation: they were considered nonfood-allergic after an eight week EDT., Conclusion and Clinical Importance: This study demonstrates that a shorter EDT is possible if the allergic pruritus and inflammation are initially controlled with a short course of glucocorticoids. This shortened trial is likely to improve owner adherence and facilitate the diagnosis of food allergy., (© 2019 ESVD and ACVD.)

Background: Dogs with year-round atopic dermatitis are often sensitized to Dermatophagoides house dust mites (HDM). Storage mites (SM) are known to grow on cereal-rich foods. Tyrophagus SM can exacerbate clinical signs of allergy in laboratory dogs sensitized to HDM. Consequently, atopic dogs with high-levels of HDM-specific IgE are likely to have a flare of signs after eating a food contaminated with SM; the development of such flares would lead to a false positive diagnosis of food allergy. Herein, we reviewed the published evidence about the growth of SM on commercial dry pet foods., Results: We searched two databases on January 25, 2019 for articles providing original information on the growth of SM on commercial dog foods. We found ten articles, five reporting results of laboratory experiments and five from field studies. Storage mites, especially Tyrophagus putrescentiae, can multiply on protein- and fat-rich dog foods. The population growth is higher when the initial mite density is high and when kibbles are crushed. When storage conditions lead to the overgrowth of molds on the kibbles, the mite proliferation is higher. Storage mites do not bore holes in food packages but invade bags via defective seals. In the field, SM contamination usually is undetectable in newly-opened commercial dog foods, and, if present, their number is low. When newly-purchased bags are stored in temperate conditions indoors, little overgrowth-if any-of SM occurs. However, when kept in environmental conditions with higher temperature and humidity, Tyrophagus mites will enter and proliferate in sealed food packages., Conclusions: Commercial dry pet foods should be kept indoors and sealed to decrease the risk of contamination with SM. When performing dietary restriction (elimination) and provocation trials for the diagnosis of food allergies in dogs, it seems preferable to choose newly-purchased bags-of both original and testing diets-to reduce the probability of their contamination with SM, especially Tyrophagus putrescentiae. In case of doubt about the presence of SM in any of these foods, one should perform food challenges with single home-cooked ingredients. Storage mite contamination might lead to an erroneous diagnosis of food allergy in HDM-sensitized dogs.

Background: Atopic dermatitis (AD) is a common disease of dogs and humans. In both species, the interplay of genetic and environmental factors affect disease expression. In dogs with AD, differences in the breed studied and in their geographical origin have led to heterogeneity in genetic association and while different loci have been identified, a causative genetic mutation has not. We hypothesized that AD could be mapped in a large cohort of rigorously phenotyped, geographically restricted West Highland White Terriers (WHWT), a breed with a high prevalence of the disease., Objectives: A) Collect phenotypes and DNA from a large cohort of WHWT born in the USA. B) Perform a genome-wide association study (GWAS) for AD in these dogs to identify associated regions and genes of interest. C) Sequence genes of interest to identify pathologic variants., Methods: We collected DNA from 96 WHWT with AD and 87 controls from the same breed. DNA was isolated and dogs were genotyped using the Illumina CanineHD BeadChip. A GWAS was performed using EMMAX and associated regions were examined for genes of interest. Genes with possible relevance to AD were examined more closely in two affected and two normal WHWT using next-generation sequencing. Variants in these genes that were unique to the two affected WHWT were compared to a database of variants derived from whole genome sequencing of 200 non-WHWT dogs across 33 additional breeds., Results: The GWAS identified a 2.7 Mb genomic region on CFA3 that included 37 genes. There was a missense variant in the F2R gene in both affected dogs but this variant was also found in 35 dogs in 9 breeds in the database of whole genome sequences for whom the phenotype regarding atopic dermatitis was unknown., Conclusions: Atopic dermatitis in WHWT is associated with a region on CFA3 that contains several candidate genes. Of these, a homozygous variant in the F2R gene present in multiple breeds that also suffer from AD warrants further evaluation., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: For decades, the efficacy of interventions in clinical trials enrolling dogs with atopic dermatitis (AD) relied on heterogeneous evaluations of skin lesions and pruritus using unvalidated tools. Although some instruments for clinical signs were validated later, there was little impact on standardizing outcome measures resulting in difficulties in comparing treatment efficacy between trials and impeding meta-analyses., Results: Participants in the Outcome Measures subcommittee of the International Committee of Allergic Diseases of Animals (ICADA) collaborated for two years to develop a core outcome set (COS) for canine AD, the COSCAD. This project involved several steps, constantly-re-assessed during online exchanges, to define the scope of this COS, to identify the relevant stakeholders, the domains to be evaluated, the instruments available for measuring agreed-upon domains and how to express outcome measures. This COSCAD'18 was designed principally for therapeutic-but not preventive or proactive-clinical trials enrolling dogs with chronic, nonseasonal (perennial), moderate-to-severe AD. Selected domains were skin lesions, pruritus manifestations and perception of treatment efficacy. Instruments to evaluate these domains were the CADESI4 or CADLI, the 10-point pruritus visual analog scale (PVAS10) and the Owner Global Assessment of Treatment Efficacy (OGATE), respectively. The COSCAD'18 has three outcome measures: the percentages of dogs with veterinarian-assessed skin lesions or owner-rated pruritus manifestation scores in the range of normal dogs or those with mild AD; the third is a good-to-excellent global assessment by the pet owners of their perception of treatment efficacy. Importantly, this COSCAD'18 is not meant to represent the sole-or primary-outcome measures evaluated in a trial; authors are always free to add any others, which they deem will best assess the efficacy of tested interventions. Benchmarks to define a threshold for treatment success were not set, as what constitutes a clinically-relevant therapeutic efficacy is expected to vary greatly depending interventions., Conclusions: This COSCAD'18 should help veterinarians and owners compare the benefits of treatments in future trials. This COS should also facilitate the combination of trial results in future systematic reviews, thereby producing more reliable summary estimates of treatment effects and enhancing evidence-based veterinary dermatology.

Background: Topical Janus kinase (JAK) inhibition is a promising therapeutic target for several inflammatory skin diseases of humans., Objectives: To evaluate the anti-inflammatory effect of tofacitinib, a JAK 1/3 inhibitor, on immediate and late-phase skin reactions in dogs., Animals: Five healthy laboratory beagle dogs., Methods: Topical tofacitinib (total daily dosage: 0.5 mg/cm 2 ) or its gel vehicle were applied on either the left or right lateral thorax of each dog for eight days. Three days before application and after eight days of topical treatment, intradermal injections of histamine and anticanine-IgE antibodies were performed on both sides; they were evaluated by an investigator blinded to the interventions., Results: The tofacitinib gel was well-tolerated; one dog developed mild erythema at Day 5 that resolved by the next application. Treatment with tofacitinib reduced histamine and anticanine-IgE global wheal scores (one-way ANOVA, P ≤ 0.005 for both) compared to baseline; there was no significant difference for the vehicle placebo (histamine; P = 0.163; IgE, P = 0.223). Late-phase reactions (LPRs) were markedly, but not significantly reduced after tofacitinib treatment (P = 0.071). A blinded histological evaluation of 6 h-anti-IgE-associated LPRs revealed a significant reduction in the total leucocyte superficial dermal cellularity (P = 0.022), as well as eosinophil (P = 0.022) and mast cell (P = 0.022) counts at tofacitinib-treated sides compared with pretreatment values. Post-treatment complete blood counts and serum chemistry profiles did not show relevant tofacitinib-induced changes., Conclusions: Our observations suggest that topical tofacitinib exerts an inhibitory effect on activated canine skin-emigrating immune cells; this drug should be investigated further as a topical immunosuppressive drug in dogs., (© 2018 ESVD and ACVD.)

Background: Cross-reactive carbohydrate determinants (CCD) are defined carbohydrate portions of glycoprotein cell surface molecules common to many plant and insect species. Mammalian species recognize CCD as foreign antigens and can mount humoral immune responses against them. Approximately 20-37% of grass and venom allergic people possess circulating IgE against CCD; these antibodies are generally considered clinically irrelevant. Anti-CCD IgE is, however, recognized as a cause of false positive, clinically incongruent serum allergen test results in people; this phenomenon has not been investigated in animals., Objective: To determine if anti-CCD IgE could be detected in sera of client-owned atopic dogs and how frequently it is found., Animals: Sera from 38 dogs with a clinical diagnosis of atopic dermatitis and prior serological evidence of IgE antibodies, defined as a positive result to at least one mite and pollen (of any type)., Methods: Sera were analysed for IgE against CCD and environmental allergens with a commercially available multiplex enzyme-labelled allergen-specific IgE assay., Results: Anti-CCD IgE was detected in nine of 38 (24%) of atopic dog sera. As with their human counterparts, all dogs with anti-CCD IgE had strong serological reactivity to grass pollens., Conclusions and Clinical Importance: Anti-CCD IgE can confound serological allergen testing in people; the same might be true in dogs. Further studies are warranted to investigate the clinical implications of anti-CCD IgE in dogs, including the potential for these antibodies to affect serum allergen-specific IgE assays used for clinical diagnosis, and whether they are relevant to clinical disease., (© 2018 ESVD and ACVD.)

Background: Studies focusing on next-generation sequencing of the bacterial 16S rRNA gene have allowed detailed surveys of skin bacterial populations (microbiota) of the skin., Hypothesis/objectives: This study evaluated temporal changes in the skin microbiota in a canine model of atopic dermatitis., Animals: Eight atopic dogs previously sensitized with house dust mites (HDM)., Methods: The dogs were topically challenged on the right groin with HDM allergens. Swabs were collected from the challenged and the contralateral nonchallenged sites prior to provocation (pre-challenge; baseline sample) and on days 1, 7, 14, 21 and 28 after allergen challenge. The 16S rRNA gene was amplified, sequenced and analysed. Staphylococcus spp. and Staphylococcus pseudintermedius were quantified with quantitative PCR (RT-qPCR)., Results: Skin lesions developed in all dogs on the challenged sites. Differences in bacterial groups were observed on the challenged site over time. Relatively lower abundances of Fusobacteriaceae on Day 7, and, based on LEfSe, increased abundances of Corynebacteriaceae on Day 1, and Staphylococcaceae on days 7, 14 and 21, were observed on the challenged site, compared to the contralateral site. Results of RT-qPCR correlated with those of next-generation sequencing, with significantly increased numbers of Staphylococcus spp. and S. pseudintermedius on Day 21, and days 7 and 21 on the challenged site compared to the contralateral site, respectively., Conclusions and Clinical Importance: This study demonstrates that an allergen challenge in sensitized dogs leads to bacterial dysbiosis with increased abundance of S. pseudintermedius at the site of lesion induction., (© 2016 ESVD and ACVD.)

Canine atopic dermatitis is a common skin disease seen in veterinary clinical practice. Several factors appear to contribute to the cutaneous inflammation and pruritus. The therapeutic strategy should focus on control of those factors that can be identified and for which interventional measures are feasible; these include ectoparasites, bacterial/fungal infection and dietary hypersensitivity. Ectoparasites, particularly fleas, are not the cause of atopic dermatitis, but they are a confounding factor, which can exacerbate pruritus, and preventative measures are therefore indicated. Bacterial and yeast infections are frequently associated with atopic dermatitis and initial systemic and/or topical therapy should be considered, followed by regular topical treatment for preventing relapse. Concurrent dietary hypersensitivity should be investigated by undertaking an elimination/provocation trial, followed by feeding of a hypoallergenic diet where appropriate. Depending on the severity of the clinical signs of atopic dermatitis and the willingness and expectations of owners, symptomatic treatment and/or specific interventional therapy for environmental allergy (allergen avoidance, allergen-specific immunotherapy) may be implemented. Symptomatic treatment includes use of glucocorticoids (systemically or topically), ciclosporin and oclacitinib. Other treatment modalities of lower or less proven efficacy include antihistamines, dextromethorphan, fatty acids, feline interferon-omega, misoprostol, pentoxifylline, specific serotonin re-uptake inhibitors and tricyclic antidepressant drugs. The therapeutic approach should be reviewed at regular intervals and tailored to the individual's needs. A successful long-term outcome can usually be achieved by combining the various treatment approaches in a way that maximises their benefits and minimises their drawbacks., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background: In 2010, the International Task Force on Canine Atopic Dermatitis (now International Committee on Allergic Diseases of Animals, ICADA) published the first consensus guidelines for the treatment of atopic dermatitis (AD) in dogs. This is the first 5-year minor update of this document., Results: The treatment of acute flares of AD should involve the search for, and then elimination of, the cause of the flares, bathing with mild shampoos, and controlling pruritus and skin lesions with interventions that include topical and/or oral glucocorticoids or oclacitinib. For chronic canine AD, the first steps in management are the identification and avoidance of flare factors, as well as ensuring that there is adequate skin and coat hygiene and care; this might include more frequent bathing and possibly increasing essential fatty acid intake. The medications currently most effective in reducing chronic pruritus and skin lesions are topical and oral glucocorticoids, oral ciclosporin, oral oclacitinib, and, where available, injectable recombinant interferons. Allergen-specific immunotherapy and proactive intermittent topical glucocorticoid applications are the only interventions likely to prevent or delay the recurrence of flares of AD., Conclusions: This first 5-year minor update of the international consensus guidelines for treatment of AD in dogs further establishes that the treatment of this disease is multifaceted, and that interventions should be combined for a proven (or likely) optimal benefit. Importantly, treatment plans are likely to vary between dogs and, for the same dog, between times when the disease is at different stages.

Background: Many studies focusing on clinical and histological signs of canine atopic dermatitis (AD) have been published since its early descriptions decades ago. Findings of these studies contributed to our current knowledge about the disease pathogenesis and allowed establishment of diagnostic criteria used by clinicians and researchers., Objectives: This review serves as an update on the clinical and histological features of canine AD published by the American College of Veterinary Dermatology Task Force on Canine Atopic Dermatitis in 2001 and summarizes the recent discoveries in these fields., Results: The overall findings of studies focusing on clinical features mirrored those published by the Task Force in 2001. The novelty was the larger number of animals included in these studies, which allowed establishment of a new set of diagnostic criteria that exceeded the sensitivity and specificity of the previous criteria. The same study uncovered some clinical differences between dogs with food-induced and nonfood-induced AD; however, the authors concluded that these two entities cannot be distinguished based on clinical signs only. Another study demonstrated some major breed-specific phenotypes. Several publications addressed the histological features of canine AD skin lesions in experimental models of AD, but none of those addressed naturally occurring lesions. Nevertheless, the histopathological description of the skin reactions was generally similar to that published by the Task Force in 2001., Conclusions: Considerable work has been done in recent years to provide a better definition of the clinical appearance and histopathology of canine AD. New sets of diagnostic criteria have been developed, and additional breed-associated differences in phenotypes have been demonstrated., (© 2015 ESVD and ACVD.)

Background: Multiple levels of evidence support the role of genetics and the environment in the pathogenesis of canine atopic dermatitis (AD)., Objectives: This review summarizes the current evidence in genetics and the effect of environmental factors on the development and perpetuation of canine AD., Methods: Citation databases, abstracts and proceedings from international meetings published between 2001 and 2013 were reviewed in this update. Where necessary, older articles were included for background information., Results: Canine AD is a heritable disease, in which interaction with environmental factors influences disease risk and phenotype. A study of British guide dogs indicated that nearly 50% of the risk of developing AD was determined by an individual's genotype. Genomic studies performed so far in canine AD have uncovered numerous gene candidates likely to be involved in pathogenesis through their role in immunity, skin barrier formation, apoptosis and inflammation. In addition to genetics, there is evidence to suggest that exposure to certain environmental factors influences the prevalence and course of canine AD. For example, living in rural areas or feeding noncommercial diets was negatively associated with the development of AD in dogs, while exposure to high levels of smoke was associated with increased prevalence of allergic skin disease., Conclusions: It is becoming clear that canine AD is genotypically complex and influenced by a variety of environmental factors. Well-designed studies with sufficient statistical power will be critical to identify the complex genetic and environmental factors involved in disease development and progression. Recognition of such factors may help to identify new targets for therapy and enable better disease prevention and management., (© 2015 ESVD and ACVD.)

Background: Topical ear medications, often containing a glucocorticoid, are used to treat the clinical signs of atopic otitis in dogs. Studies have looked at the inhibitory effect of topical glucocorticoids on intradermal testing (IDT), but only one previously published study evaluated the influence of an otic glucocorticoid on the results of IDT in dogs., Hypothesis/objectives: To assess what influence the absorption of the diester glucocorticoid mometasone furoate (MF) had on intradermal test immediate reactions, to determine an appropriate withdrawal time prior to IDT., Methods: Twenty atopic dogs were enrolled. On day 0, histamine, rabbit anticanine IgE antiserum and saline were injected intradermally. After 20 min, a global wheal score (GWS) was determined. The otic medication, MF, was applied once daily for 14 days. Intradermal injections were then repeated and, if the GWS was within 25% of pretreatment values, the study was completed for this dog. If the GWS had decreased by ≥25% from the baseline value, the otic medication was withdrawn, and the GWS was repeated every 7 days until its value was within 25% of the original GWS., Results: Three of the 20 dogs completed the study on day 14, while 17 of 20 dogs ended it on day 21, 7 days after withdrawal of the drug, MF., Conclusions and Clinical Importance: Results from this study show that a withdrawal period of ≤7 days is possible before performing IDT in atopic dogs with active otitis externa treated with ≤14 days of MF., (© 2014 ESVD and ACVD.)

Background: The stratum corneum is critical for providing a functional skin barrier, especially in humans and dogs with atopic dermatitis. An effective barrier also depends upon intact corneodesmosomes and superficial epidermal tight junctions., Hypothesis/objectives: To study the expression of selected corneodesmosome, desmosome, tight and adherens junction proteins in an experimental model of acute atopic dermatitis skin lesions in dogs., Methods: Control and house dust mite (HDM) allergen-containing patches (two types of patches) were applied to the skin of six Maltese-beagle atopic dogs hypersensitive to HDM. Patches were left on for 48 h, and biopsies were collected 24 h after removal. Frozen skin sections were stained by indirect immunofluorescence for corneodesmosin, desmoglein-1, desmocollin-1, claudin-1 and E-cadherin. Immunostains were assessed for their extent, intensity and patterns; they were compared between HDM and control patches on the same dogs., Results: The immunostaining for E-cadherin, desmocollin-1 and desmoglein-1 was homogeneous, intercellular and continuous in all control and HDM patches. The immunoreactivity of corneodesmosin and claudin-1 was heterogeneous and reduced in intensity in 12 of 12 and eight of 12 HDM patches, respectively, in contrast to a normal expression seen in all control samples (Fisher's test, P < 0.001)., Conclusions and Clinical Importance: These observations suggest that HDM allergens, via proteolytic digestion and/or because of induced allergic inflammation, affect the expression and possible function of corneodesmosomal and tight junction proteins. Ensuing intercellular junction alterations might promote an abnormally increased penetration of allergens through the epidermis., (© 2014 ESVD and ACVD.)

Background: Severity scales are used to grade skin lesions in clinical trials for treatment of dogs with atopic dermatitis (AD). At this time, only two scales have been validated, namely the Canine Atopic Dermatitis Extent and Severity Index (CADESI)-3 and the Canine Atopic Dermatitis Lesion Index (CADLI). However, the high number of assessed sites makes the CADESI-3 impractical., Hypothesis/objectives: The aim of this study was to develop and validate a fourth version of the CADESI that is simpler and quicker to administer., Methods: Body sites, lesions and severity grades were revised by members of the International Committee on Allergic Diseases of Animals (ICADA). The newly designed CADESI-4 was tested for its validity (i.e. content, construct and criterion), reliability (i.e. inter- and intra-observer reliability and internal consistency), responsiveness (i.e. sensitivity to change) and time to administer. Disease severity benchmarks were chosen using receiver operating characteristic methodology., Results: The CADESI-4 was simplified in comparison to its previous version to comprise 20 body sites typically affected in atopic dogs. Three lesions (erythema, lichenification and alopecia/excoriation) were scored from 0 to 3 at each site. The CADESI-4 had satisfactory validity, reliability and sensitivity to change. On average, the time to administer a CADESI-4 was one-third that of a CADESI-3. Proposed benchmarks for mild, moderate and severe AD skin lesions are 10, 35 and 60, respectively., Conclusions and Clinical Importance: The CADESI-4 is simpler to use and quicker to administer than its previous version. The ICADA recommends the CADESI-4 instead of the CADESI-3 to score skin lesions of AD in dogs enrolled in clinical trials., (© 2014 ESVD and ACVD.)

Background: Intradermal testing is useful for the identification of environmental allergens to which cats could be hypersensitive; intradermal test reactions are often subtle and difficult to interpret in cats. Percutaneous testing is the standard technique for the detection of significant environmental allergens in people, but it has not yet been evaluated in cats with hypersensitivity dermatitis., Hypothesis/objectives: The purpose of this study was to evaluate and compare the skin test responses of healthy cats to percutaneous application and intradermal injections of control solutions., Methods: Ten clinically healthy cats were studied. Percutaneous applications of 0.0275 and 0.1 mg/mL aqueous histamine, 6 mg/mL glycerinated histamine, 0.9% buffered saline and 50% glycerosaline solution were performed using Greer Pick (Greer Laboratories, Lenoir, NC, USA) and Duotip-Test II (Lincoln Diagnostics, Decatur, IL, USA) percutaneous applicators. Reactions were compared with intradermal injections of 0.0275 mg/mL aqueous histamine and 0.9% buffered saline as controls., Results: Positive responses to histamine solutions were significantly greater with the Greer Pick than with the Duotip-Test II. There were no significant differences between the histamine reactions using the Greer Pick applicator and the intradermal injections. Percutaneous reactions to histamine were more well demarcated and easier to read than intradermal injection reactions. Reactions to the saline controls were not noted., Conclusions and Clinical Importance: Percutaneous application of 6 mg/mL glycerinated histamine solution, 50% glycerosaline solution and 0.9% buffered saline produced similar positive and negative control wheals. These observations warrant further studies of percutaneous allergen testing in cats with hypersensitivity dermatitis., (© 2013 ESVD and ACVD.)