Evaluation of the effect of a 0.0584% hydrocortisone aceponate spray on clinical signs and skin barrier function in dogs with atopic dermatitis

The purpose of this study was to evaluate the effects of a topical spray containing 0.0584% hydrocortisone aceponate (HCA) on canine atopic dermatitis (CAD) and to evaluate the skin barrier function during the treatment of CAD. Twenty-one dogs that fulfilled the diagnostic criteria for CAD were included in this study. The HCA spray was applied once a day to the lesions of all dogs for 7 or 14 days. Clinical assessment was performed before (day 0) and after treatment (day 14), and clinical responses were correlated with changes in skin barrier function. CAD severity significantly decreased after 14 days of HCA treatment based on the lesion scores (p < 0.0001), which were determined using the CAD extent and severity index (CADESI-03) and pruritus scores (p < 0.0001) calculated using a pruritus visual analog scale. Transepidermal water loss, a biomarker of skin barrier function, was significantly reduced compared to baseline (day 0) measurements (p = 0.0011). HCA spray was shown to be effective for significantly improving the condition of dogs suffering from CAD. This treatment also significantly improved cutaneous hydration and skin barrier function in the animals.     

The influence of topical unsaturated fatty acids and essential oils on normal and atopic dogs

Seven dogs with atopic dermatitis and six normal dogs were treated with a spot-on product containing essential oils and unsaturated fatty acids q 7 days for 8 wk. Seven additional atopic dogs received a daily spray containing similar ingredients to the spot-on. In all dogs, transepidermal water loss (TEWL) was measured before and after treatment using a closed chamber device. In atopic dogs, a validated lesion score (canine atopic dermatitis extent and severity index, CADESI) was determined and pruritus was assessed with a visual analog scale before and after treatment. The mean CADESI scores in atopic dogs decreased with the spot-on (P=0.0043) and with the spray (P=0.0366). Similarly, the pruritus scores decreased with the spot-on (P=0.266) and with the spray (P=0.0177). There was a significant difference between the TEWL values of healthy and atopic dogs on the abdomen (P=0.0181) and back (P=0.0123). TEWL decreased significantly on the back after treatment with the spray (P=0.016), but not on the abdomen (P=0.078). Adverse effects were not observed. The results of this pilot study indicate that topical fatty acids and essential oils are a useful treatment option for canine atopic dermatitis.     

Are transepidermal water loss and clinical signs correlated in canine atopic dermatitis? A compilation of studies

Background – Cutaneous impairment plays a crucial role in atopic dermatitis (AD). Transepidermal water loss (TEWL) measurement is an indirect assessment of skin barrier function and correlates with disease severity in humans. Skin impairment also exists in canine AD; however, concerns exist regarding variability and reliability of TEWL measurements in dogs. Hypothesis/Objectives – The purposes of this retrospective study were twofold: first, to investigate the correlation between severity of dermatitis [measured by Canine Atopic Dermatitis Extent and Severity Index (CADESI)] and TEWL; and second, to evaluate whether increased TEWL at a young age correlates with disease severity later in life. Methods – Data from atopic beagles and dogs with natural AD were analysed. Transepidermal water loss was measured in atopic beagles (n = 24) with an open chamber and in dogs with naturally occurring AD with a closed chamber device (two studies, with n = 14 and n = 18). Pearson product–moment correlation was used for analyses. Transepidermal water loss of the inguinal region, axilla, antebrachial flexure and pinna was analysed. Correlations were investigated for each study, separately first and then jointly. They included CADESI and TEWL of individual regions, total CADESI and total TEWL of all measured regions, and total CADESI and TEWL of key regions. Results – In atopic beagles, TEWL measured at 1 year of age pre‐ and post‐allergen challenge was correlated with CADESI at 1, 3 and 6 years of age. Overall, low correlation coefficients were found; therefore, a biologically relevant connection could not be demonstrated. The main significant positive correlation was found between TEWL in the pinna and total CADESI. Conclusions and clinical importance – It is concluded that TEWL does not correlate with disease severity.     

Assessment of a correlation between Canine Atopic Dermatitis Extent and Severity Index (CADESI-03) and selected biophysical skin measures (skin hydration,pH, and erythema intensity) in dogs with naturally occurring atopic dermatitis

Atopic dermatitis is a common allergic skin disease in dogs. The aim of this study was to examine the possibility of a correlation between biophysical skin variables: skin hydration (SH), skin pH, and erythema intensity measured in 10 different body regions and both total Canine Atopic Dermatitis Extent and Severity Index (CADESI-03) and CADESI measured in a given region (CADESI L). The study was conducted using 33 dogs with atopic dermatitis. The assessment of the biophysical variables was done in 10 body regions: the lumbar region, right axillary fossa, right inguinal region, ventral abdominal region, right lateral thorax region, internal surface of the auricle, interdigital region of right forelimb, cheek, bridge of nose, and lateral site of antebrachum. Positive correlations were found between SH and CADESI L for the following regions: the inguinal region (r = 0.73) and the interdigital region (r = 0.82), as well as between total CADESI and SH on digital region (r = 0.52). Also, positive correlations were reported for skin pH and CADESI L in the lumbar region (r = 0.57), the right lateral thorax region (r = 0.40), and the lateral antebrachum (r = 0.35). Positive correlations were found in the interdigital region between erythema intensity and the total CADESI-03 (r = 0.60) as well as the CADESI L (r = 0.7). The results obtained suggest that it may be possible to use skin hydration, pH, and erythema intensity to assess the severity of skin lesion but positive correlation was only found in < 13.3% of possible correlations and usage of these measures in dogs is limited.     

Oxidative stress markers in canine atopic dermatitis

There are no data in the veterinary literature relating to oxidative stress in canine atopic dermatitis (CAD). The study aimed to determine levels of oxidative stress markers, plasma malondialdehyde (MDA), total antioxidant capacity (TAC), whole blood glutathione peroxidase (GPX) and erythrocyte superoxide dismutase (SOD), in 15 CAD patients and 17 healthy dogs. A correlation between CADESI (Canine Atopic Dermatitis Extent and Severity Index) score and MDA was also determined. Significantly higher plasma MDA levels were found in patients than in healthy dogs. The significant, highly positive correlation determined between CADESI score and MDA in the patient group indicates an association between the severity of CAD and the extent of oxidative damage to membrane lipids. There were no significant differences in TAC, GPX and SOD between patients and healthy dogs. Our findings suggest that oxidative stress with increased lipid peroxidation could be involved in the pathogenesis of atopic dermatitis in dogs.     

Is the skin barrier abnormal in dogs with atopic dermatitis?

In mammalian skin, the stratum corneum exerts a barrier function that protects from transepidermal water loss and the penetration of exogenous molecules, such as allergens, from the environment. Recently, skin barrier defects have been shown to be of prime importance in the pathogenesis of human atopic dermatitis. In this review, we summarize the latest research data pertinent to the stratum corneum and barrier function of dogs with atopic dermatitis. At the time of this writing, there is increasing evidence that a skin barrier defect likely exists in dogs with atopic dermatitis. This barrier dysfunction is characterized by abnormal intercellular stratum corneum lipid lamellae, abnormal stratum corneum morphology, reduced and abnormal ceramide content and, in some but not all dogs, abnormal filaggrin expression. In association with these changes, there is higher transepidermal water loss in atopic than in normal canine skin. Furthermore, atopic inflammation appears to worsen transepidermal water loss and filaggrin expression. It remains unknown, however, if the changes observed are primary (i.e. of genetic origin) or secondary to atopic inflammation that also exists even in clinically normal skin. Finally, whether or not a therapeutic intervention aimed at restoring a dysfunctional skin barrier is of any clinical benefit to atopic dogs has not yet been proven unequivocally.     

Transepidermal water loss in healthy and atopic dogs, treated and untreated: a comparative preliminary study

An impaired skin barrier function is thought to be crucial for allergic sensitization. In humans, the skin barrier is assessed by noninvasive methods, such as the measurement of transepidermal water loss (TEWL). Although limitations have been reported, measurement of TEWL has been demonstrated to be a suitable method to assess barrier function indirectly in dogs. The purposes of this prospective clinical study were twofold. The first aim was to evaluate and compare TEWL in healthy and atopic dogs. The second aim was to evaluate TEWL in a population of atopic dogs and to assess TEWL in dogs whose disease was in remission after successful therapy and compare it with dogs whose disease was not controlled or receiving treatment. One hundred and fifty dogs were selected and divided into the following three groups: 50 atopic dogs before specific treatment (group A); 50 in remission (group B); and 50 control dogs (group C). The mean values for TEWL for each group were 22.47 (g/m(2) h) (group A; 95% confidence interval 20.85-24.09), 12.57 (g/m(2) h) (group B; 95% confidence interval 11.43-13.7) and 8.81 (g/m(2) h) (group C; 95% confidence interval 8.09-9.52); P-value was 0.0001 for TEWL (groups A, B and C). This study showed a significant difference of TEWL between healthy control dogs and dogs with atopic dermatitis. Additionally, TEWL was lower in atopic dogs whose disease was in remission due to treatment. These results were consistent with reports in human medicine about TEWL.     

Ciclosporin therapy is associated with minimal changes in calcium metabolism in dogs with atopic dermatitis

Background – Ciclosporin is widely used in the management of canine atopic dermatitis. In humans, ciclosporin therapy has been linked to disturbances in calcium metabolism and resultant skeletal disorders. Objectives – The objective of this study was to assess calcium homeostasis in dogs before and after a 6 week course of once daily oral ciclosporin at the licensed dose (5 mg/kg). Animals – Sixteen client‐owned dogs with spontaneous atopic dermatitis. Methods – Serum concentrations of calcium, phosphate, creatinine, 25‐hydroxyvitamin D, 1,25‐dihyroxyvitamin D and plasma concentrations of ionized calcium and parathyroid hormone (PTH) were measured, together with the urinary fractional excretion of calcium and phosphate. The extent of skin lesions was scored using the Canine Atopic Dermatitis Extent and Severity Index (CADESI)‐03 and the degree of pruritus by the Edinburgh Pruritus Scale prior to and at the end of the study. Results – The CADESI‐03 and the Edinburgh Pruritus Scale scores decreased satisfactorily in all dogs by the end of the study. Plasma PTH concentrations were significantly increased (P = 0.02) following ciclosporin treatment, whereas all other biochemical parameters were not significantly different from their starting values. The increase in PTH was mild in most cases and the proportion of dogs that had a PTH concentration above the reference range was not significantly different following treatment. Conclusions and clinical importance – This study indicates that ciclosporin has minimal impact on calcium metabolism in dogs with atopic dermatitis when used at the licensed and clinically effective dosage for 6 weeks.     

The effect of nematode administration on canine atopic dermatitis

Canine atopic dermatitis is a common disease and is considered as an animal model of the human disease. Immunomodulation by helminths is reported in several species. The aim of this study was to determine whether nematodes have an immunomodulatory effect on atopic dermatitis in dogs. In the pilot study, 12 atopic dogs were infected with either embryonated eggs of Trichuris vulpis (500 and 2500 eggs in 3 dogs each) or L3 larvae of Uncinaria stenocephala (100, 500 and 2500 eggs in 2 dogs each), respectively, for 3 months. Pruritus was evaluated with visual analogue scales and clinical lesions with the canine atopic dermatitis extent and severity index (CADESI). Skin biopsies were obtained for histopathology at the beginning and end of the study. In the subsequent placebo-controlled, double-blinded, randomised study, 21 dogs received either 2500 embryonated T. vulpis eggs or placebo and were evaluated similarly. In addition, allergen-specific serum IgE concentrations were determined. All dogs in the pilot study improved in their lesion scores, most in their pruritus scores. The cutaneous inflammatory infiltrate did not change significantly. In the subsequent randomised study, there was no significant difference between placebo and Trichuris administration in regard to pruritus or CADESI. IgE concentrations also did not change significantly. Infection with T. vulpis did not significantly change clinical signs of canine atopic dermatitis.     

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

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

FC-38 Efficacy of conjugated linoleic acid and black currant seed oil in the treatment of canine atopic dermatitis: a double-blinded, randomized, placebo-controlled study

The purpose of this study was to evaluate a combination of immunostimulatory bacterial DNA sequences and allergen-specific immunotherapy for the treatment of canine atopic dermatitis. Seven dogs with nonseasonal atopic dermatitis diagnosed by history, clinical signs and exclusion of differential diagnoses were included. All dogs had been on allergen-specific immunotherapy for at least 12 months with incomplete responses, were on additional antipruritic therapy and showed residual pruritus. Pruritus was marked by the owner on a visual analogue scale, lesions were determined by a clinician using the Canine Atopic Dermatitis Extent and Severity Index (CADESI), and concurrent medications were recorded before entering the study and after 14 weeks of treatment. Peripheral blood mononuclear cells were isolated and cultured; canine cytokine message for IFNγ, IL-4, TNF and IL-10 was quantitated using RT-PCR. A mixture of allergen extract and liposome-DNA complexes was injected intradermally at the beginning of the study and after 2, 4, 6, 10 and 14 weeks. CADESI, pruritus and medication scores, and cytokine messages at the beginning and end of the study were compared with a paired t -test. There were significant improvements in pruritus scores ( P  = 0.0277). Reductions in medication scores and CADESI were not statistically significant. IL-4 production decreased significantly ( P  = 0.0428); decreases in other cytokines were not significant. Although the number of dogs in this pilot study was small, the results warrant further investigation of a combination of immunostimulatory bacterial DNA sequences and allergen-specific immunotherapy for the treatment of canine atopic dermatitis.
Funding: Self-funded.     

Pilot evaluation of the efficacy of shampoo treatment with ultrapure soft water for canine pruritus

Ultrapure soft water (UPSW) is water in which calcium and magnesium ions have been replaced with sodium ions using a cation‐exchange resin. We recently demonstrated that washing with soap and UPSW reduced the clinical severity of dermatitis and improved the skin barrier function in NC/NgaTnd mice, a murine model for human atopic dermatitis. The purpose of this pilot study was to evaluate the efficacy of shampoo treatment with UPSW for dogs with pruritus. Eleven dogs with pruritus were randomly assigned to two groups depending on whether they received weekly shampoo treatment with UPSW or tap water for 4 weeks. After a washout period, the treatment protocol was switched such that each dog received both treatments. The pre‐treatment and post‐treatment values of the following were compared: pruritus scores assessed by the owners; dermatitis scores recorded by an investigator; and transepidermal water loss (TEWL). Shampoo treatment with UPSW significantly decreased pruritus and dermatitis scores in the dogs, whereas shampoo treatment with tap water did not. In addition, shampoo treatment with UPSW, but not with tap water, significantly reduced TEWL in the dogs. Adverse events due to the treatment were not observed in the dogs. Furthermore, we found that topical application of UPSW for barrier‐disrupted skin caused by tape stripping in healthy dogs decreased TEWL more rapidly than topical application of tap water. Our findings suggest that shampoo treatment with UPSW promotes skin barrier recovery and thus could be considered as a possible therapeutic option in the management of pruritus and dermatitis in dogs.     

FC‐36 The use of immunostimulatory bacterial DNA sequences in allergen‐specific immunotherapy of canine atopic dermatitis

The purpose of this study was to evaluate a combination of immunostimulatory bacterial DNA sequences and allergen‐specific immunotherapy for the treatment of canine atopic dermatitis. Seven dogs with nonseasonal atopic dermatitis diagnosed by history, clinical signs and exclusion of differential diagnoses were included. All dogs had been on allergen‐specific immunotherapy for at least 12 months with incomplete responses, were on additional antipruritic therapy and showed residual pruritus. Pruritus was marked by the owner on a visual analogue scale, lesions were determined by a clinician using the Canine Atopic Dermatitis Extent and Severity Index (CADESI), and concurrent medications were recorded before entering the study and after 14 weeks of treatment. Peripheral blood mononuclear cells were isolated and cultured; canine cytokine message for IFNγ, IL‐4, TNF and IL‐10 was quantitated using RT‐PCR. A mixture of allergen extract and liposome‐DNA complexes was injected intradermally at the beginning of the study and after 2, 4, 6, 10 and 14 weeks. CADESI, pruritus and medication scores, and cytokine messages at the beginning and end of the study were compared with a paired t‐test. There were significant improvements in pruritus scores (P = 0.0277). Reductions in medication scores and CADESI were not statistically significant. IL‐4 production decreased significantly (P = 0.0428); decreases in other cytokines were not significant. Although the number of dogs in this pilot study was small, the results warrant further investigation of a combination of immunostimulatory bacterial DNA sequences and allergen‐specific immunotherapy for the treatment of canine atopic dermatitis. Funding: Self‐funded.     

The efficacy of commercially available veterinary diets recommended for dogs with atopic dermatitis

The classical treatments for dogs with atopic dermatitis have traditionally been oral antipruritic drugs, allergen-specific immunotherapy and topical therapy. Fifty dogs with atopic dermatitis were included in this multicentred, double-blinded, randomized study to compare clinical response to an 8-week period of feeding one of three commercial veterinary foods marketed for dogs with atopic dermatitis (diets A-C) or a widely distributed supermarket food (diet D). Atopic dermatitis was diagnosed using Willemse's criteria and through the exclusion of differential diagnoses. Fourteen dogs were assigned to diet A and 12 dogs each to diet B, C or D. Flea and tick control using a monthly fipronil spot-on product was administered for a minimum of 4 weeks prior to inclusion in the study and during the study period. Evaluations were made monthly. These included lesion scores, using an established scoring system (canine atopic dermatitis extent and severity index, CADESI-03) and owner evaluation of pruritus level using a visual analogue scale. After 8 weeks on the new diets, there was a significant improvement in CADESI and pruritus scores with diet B (Wilcoxon test, P = 0.043 and paired t-test, P = 0.012, respectively), in pruritus scores with diet A (paired t-test, P = 0.019) and in CADESI scores with diet D (Wilcoxon test, P = 0.037). No significant changes were detected with diet C. Based on the results of this study, in addition to the conventional therapies, changing the diet of dogs with atopic dermatitis may be a useful adjunctive therapeutic measure.     

The effect of a spot-on formulation containing polyunsaturated fatty acids and essential oils on dogs with atopic dermatitis

Recent studies have shown that immunological aberrations and epidermal barrier defects could be important in the pathogenesis of canine atopic dermatitis (CAD) and that oral polyunsaturated fatty acids (PUFAs) might influence the epidermal barrier. The aim of this study was to evaluate the effects of a spot-on formulation containing PUFAs and essential oils on pruritus and lesions caused by CAD. Forty-eight privately owned dogs of different breeds, ages and genders diagnosed with atopic dermatitis were included in a randomized, double-blinded, placebo-controlled, multicentre clinical trial. Dogs were treated with a spot-on formulation containing PUFAs and essential oils or placebo on the dorsal neck once weekly for 8 weeks. Before and after the study, CAD extent and severity index-03 (CADESI-03) and pruritus scores were determined by veterinarians and owners, respectively.There was significantly more improvement in CADESI-03 and pruritus scores in the treatment group than in the placebo group (P = 0.011 and P = 0.036, respectively). Additionally, more dogs improved by at least 50% in CADESI-03 and pruritus scores in the treatment group than in the placebo group (P = 0.008 and P = 0.070, respectively). No adverse reactions were observed. The topical preparation containing PUFAs and essential oils was a safe treatment and beneficial in ameliorating the clinical signs of CAD.     

Histologic morphology and involucrin, filaggrin, and keratin expression in normal canine skin from dogs of different breeds and coat types

The purpose of this study was to measure the thickness of canine epidermis at various anatomical sites according to localization of cornified envelopes (involucrin and filaggrin), keratins (keratin 10, 5), and their mRNA expression. This was done in the skin of five breeds of dogs including seven poodles, six golden retrievers, six Shih Tzus, four pugs, and four Labrador retrievers. Epidermal thickness of the stratum corneum and nucleated epidermal layer was significantly different. The greatest thickness was observed in the digital web area and the thinnest epidermis was in the axilla. Epidermal thickness was also significantly different between the breeds (p < 0.05). Immunohistochemical staining scores revealed significant decreases of involucrin, filaggrin, and keratin 10 in the ventral and weight-bearing sites, and a relative increase of keratin 5 (p < 0.05). q-PCR analysis showed that their the levels of mRNA were positively correlated with expression of the corresponding proteins in skin samples (p < 0.05). The present study is the first to report the relationship between epidermal gene expression and histologic morphology of the skin in normal dogs. Further studies will be essential to fully understand the pathogenesis of skin barrier dysfunctions in canines.     

The ACVD task force on canine atopic dermatitis (VIII): is the epidermal lipid barrier defective?

In humans with atopic dermatitis (AD), it is suspected that the epidermal lipid barrier is abnormal because of combined insufficient extrusion of lipid-containing organelles into the superficial epidermal intercellular spaces as well as skin lipid metabolic defects. To date, studies investigating skin hydration and lipids in atopic dogs are scarce and unfortunately have yielded conflicting data. Whether or not dogs with AD exhibit dry skin and an inadequate stratum corneum barrier, therefore, remains the subject of speculation.     

Efficacy of an essential fatty acid-enriched diet in managing canine atopic dermatitis: a randomized, single-blinded, cross-over study

Evidence suggests that high-quality diets enriched with essential fatty acids (EFA) and other nutrients can ameliorate canine atopic dermatitis (AD). This study compared such a diet (Eukanuba Veterinary Diets Dermatosis FP) with a home-cooked equivalent (fish and potato) in a randomised, single-blinded, cross-over trial. Twenty dogs with perennial AD were randomly assigned to receive either the test (group A) or the control diet (group B) for 1 month, followed by the contrasting diet for a further month. Canine Atopic Dermatitis Extent and Severity Index (CADESI version 2) and pruritus (visual analogue scale) scores were recorded at days 0, 30 and 60. Eight dogs in each group completed the study. CADESI scores significantly declined when dogs were fed the test diet (group A P < 0.01; group B P < 0.001), and increased (group A P < 0.05) or remained steady (group B) on the control diet. CADESI scores decreased in 15 of 16 dogs fed the test diet, but this was less than 50% in all cases. Pruritus scores also declined when dogs were fed the test diet compared to the control diet, but this was only significant for group A (P = 0.027). Pruritus was reduced in 11 of 16 dogs fed the test diet, but this was 50% or more in only two dogs. This trial provides evidence for the efficacy of Eukanuba Veterinary Diets Dermatosis FP in canine AD, although it is likely that most cases will require adjunct therapy. The mechanism is unclear, but may involve increased and balanced EFA levels.     

Characterization of canine filaggrin: gene structure and protein expression in dog skin

Background – Filaggrin (FLG) is a key protein for skin barrier formation and hydration of the stratum corneum. In humans, a strong association between FLG gene mutations and atopic dermatitis has been reported. Although similar pathogenesis and clinical manifestation have been argued in canine atopic dermatitis, our understanding of canine FLG is limited. Hypothesis/Objectives – The aim of this study was to determine the structure of the canine FLG gene and to raise anti‐dog FLG antibodies, which will be useful to detect FLG protein in dog skin. Methods – The structure of the canine FLG gene was determined by analysing the publicly available canine genome DNA sequence. Polyclonal anti‐dog FLG antibodies were raised based on the canine FLG sequence analysis and used for defining the FLG expression pattern in dog skin by western blotting and immunohistochemistry. Results – Genomic DNA sequence analysis revealed that canine FLG contained four units of repeated sequences corresponding to FLG monomer protein. Western blots probed with anti‐dog FLG monomer detected two bands at 59 and 54 kDa, which were estimated sizes. The results of immunohistochemistry showed that canine FLG was expressed in the stratum granulosum of the epidermis as a granular staining pattern in the cytoplasmic region. Conclusions and clinical importance – This study revealed the unique gene structure of canine FLG that results in production of FLG monomers larger than those of humans or mice. The anti‐dog FLG antibodies raised in this study identified FLG in dog skin. These antibodies will enable us to screen FLG‐deficient dogs with canine atopic dermatitis or ichthyosis.