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Tympanokeratomas (cholesteatomas) are destructive keratinic masses of the middle ear that are often treated surgically. In humans, nonechoplanar (non-EP) diffusion-weighted (DW) MRI is efficient in diagnosing tympanokeratomas and differentiating recurrent tympanokeratomas from granulation or fibrous tissue after surgery. The objectives of this study were to (1) determine the characteristics of non-EP DWI of histologically or cytologically confirmed canine tympanokeratomas, (2) determine the performance of non-EP DW images, apparent diffusion coefficient (ADC) map and ADC values in discriminating between tympanokeratomas and other causes of otitis media in dogs, and (3) find an optimal ADC cut-off value. Medical records of dogs diagnosed on MRI with otitis media in two veterinary hospitals were retrospectively reviewed. Sixty-two ears with a cytological or pathological diagnosis of either tympanokeratoma (36/62) or nontympanokeratoma otitis media (26/62) were selected. Diffusion-weighted images had an accuracy of 77.4%, a sensitivity of 94.4%, and a specificity of 53.8% for the detection of tympanokeratoma. The ADC value of middle ear content ranged from 517 to 1355.10 -6  mm 2 /s in tympanokeratoma and from 454 to 2447 × 10 -6  mm 2 /s in nontympanokeratoma otitis media. An ADC value below 916 × 10 -6  mm 2 /s interpreted as a tympanokeratoma yielded an accuracy of 78.7%, a sensitivity of 92.6%, and a specificity of 60%. In the study population, combined qualitative analysis of DW images and ADC maps was the most effective method for diagnosing tympanokeratomas with an accuracy of 80.9%, a sensitivity of 92.6%, and a specificity of 65%., (© 2024 The Author(s). Veterinary Radiology & Ultrasound published by Wiley Periodicals LLC on behalf of American College of Veterinary Radiology.)

(1) Background: Dysbiosis is frequently observed in Canine Atopic Dermatitis (CAD). Antimicrobial treatment may be necessary to treat flare ups and the use of topical treatments is beneficial to prevent the development of bacterial resistance. Wipes are an easy way to apply antiseptic agents on the skin. The aim of this study was to evaluate the benefits of 3% chlorhexidine impregnated wipes (Pyoskin ® wipes, MP Labo, France) on local areas of dysbiosis in dogs with CAD. (2) Methods: A total of 20 dogs suffering from CAD presented with localised areas of dysbiosis were included in this study. Affected areas were cleansed with the daily application of chlorhexidine wipes once a day for 14 days. Follow-up visits were scheduled after one and two weeks. Clinical signs (lesions and pruritus), dysbiosis scored by cytological counts (cocci and Malassezia ) and investigator and owner global appreciation were evaluated. (3) Results: A statistically significant decrease in clinical scores and cytological counts were observed as soon as D7 and until D14. Both owner and investigator appreciation were considered high (4) Conclusions: The use of chlorhexidine impregnated wipes is a useful and easy way to manage localised dysbiosis in atopic dogs and allows limiting of systemic medication to prevent bacterial resistance.

Background: Lokivetmab is an effective treatment for atopic dermatitis (AD) in dogs. The aim of this prospective study was to determine if topical products containing plant extracts could enhance the clinical efficacy of lokivetmab., Animals: Thirty atopic dogs were included., Methods and Materials: Dogs were allocated randomly to be treated either with a single injection of lokivetmab (mean dose 1.34 mg/kg; Group A) or to a single injection (mean dose 1.28 mg/kg) coupled with a weekly topical treatment using a shampoo and a spot-on specifically designed to improve skin barrier defect (Group B). Clinical parameters evaluated included pruritus (pruritus Visual Analog Scale) and skin lesions (Canine Atopic Dermatitis Lesion Index, CADLI); cosmetic evaluation, and owner and investigator global assessment of efficacy (OGATE) also were carried out. Dogs were re-examined after 10, 17 and 31 days, and until a clinical relapse occurred., Results: An improvement was noted for all dogs, with scores being significantly better in dogs in Group B than in those in Group A; after 10 days for cosmetic evaluation, 17 days for pruritus (P = 0.039) and OGATE, and 31 days for CADLI (P = 0.043). A longer-lasting remission was noted in Group B compared to Group A; dogs receiving the combined treatment showed an extended time to flare compared to dogs treated with lokivetmab alone (P = 0.012)., Conclusions and Clinical Importance: This study suggests that combining lokivetmab with topical therapies designed to repair the skin barrier potentially have value in the treatment of AD in dogs., (© 2021 ESVD and ACVD.)

Background: The use of concurrent medications is necessary in trials of treatment of canine atopic dermatitis. Our aim was to use the best available evidence to construct and then to validate a medication score (MS) formula that will estimate the impact of concurrent medications on trial outcomes., Methods: Trials of 15 interventions were scrutinized to find those that were consistent in terms of specific medication, administration route and dosage regimen. A MS was constructed in five steps, starting from assigning a score of 1 for each day on oral prednisone, prednisolone or methylprednisolone at 0.5-1.0 mg/kg. The MS score was validated using the clinical records of 35 dogs with atopic dermatitis that had been treated for a period of 12 ± 2 weeks with six of these medications and compared with a previously published non-validated MS., Results: A MS could be assigned to eight treatments, six of which had been administered to the 35 dogs. A positive correlation was seen with the previously published MS and a negative correlation with changes in lesional and pruritus scores., Conclusion: This MS may be a useful tool in new studies evaluating the efficacy of treatments in canine atopic dermatitis., (© 2021 British Veterinary Association.)

Background: Demodicosis is a common disease in small animal veterinary practice worldwide with a variety of diagnostic and therapeutic options., Objectives: To provide consensus recommendations on the diagnosis, prevention and treatment of demodicosis in dogs and cats., Methods and Materials: The authors served as a Guideline Panel (GP) and reviewed the literature available before December 2018. The GP prepared a detailed literature review and made recommendations on selected topics. A draft of the document was presented at the North American Veterinary Dermatology Forum in Maui, HI, USA (May 2018) and at the European Veterinary Dermatology Congress in Dubrovnik, Croatia (September 2018) and was made available via the World Wide Web to the member organizations of the World Association for Veterinary Dermatology for a period of three months. Comments were solicited and responses were incorporated into the final document., Conclusions: In young dogs with generalized demodicosis, genetic and immunological factors seem to play a role in the pathogenesis and affected dogs should not be bred. In old dogs and cats, underlying immunosuppressive conditions contributing to demodicosis should be explored. Deep skin scrapings are the diagnostic gold standard for demodicosis, but trichograms and tape squeeze preparations may also be useful under certain circumstances. Amitraz, macrocyclic lactones and more recently isoxazolines have all demonstrated good efficacy in the treatment of canine demodicosis. Therapeutic selection should be guided by local drug legislation, drug availability and individual case parameters. Evidence for successful treatment of feline demodicosis is strongest for lime sulfur dips and amitraz baths., (© 2019 ESVD and ACVD, Veterinary Dermatology.)

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: Autoimmune subepidermal blistering dermatoses (ASBD) are a group of severe autoimmune dermatoses rarely described in dogs. Their treatment usually necessitates the long term use of medications potentially associated with adverse effects. In humans, Janus Kinase (JAK) inhibitors have been demonstrated to be of value in some cases of autoimmune skin disease., Hypothesis/objectives: To evaluate oral oclacitinib, a JAK-1 predominant inhibitor, in one case of ASBD in a dog., Case Report: A 5-year-old German shepherd cross-bred dog was presented with an acute onset of ulcerative and blistering skin lesions on the face, oral cavity, lateral trunk and limbs. Associated systemic signs were not seen. A clinical diagnosis of ASBD was supported by the finding of subepidermal clefts and visualization of the epidermal basement membrane zone at the bottom of the clefts on histopathological examination. Treatment was initiated with prednisolone at 1.2 mg/kg twice daily. Because of severe adverse effects and relapse, when the prednisolone dose was reduced, oclacitinib therapy was administered at 0.5 mg/kg twice a day. A complete resolution of clinical signs was noted after one month and no relapse was observed after twelve months of treatment. No adverse effects were reported., Conclusion: The use of oclacitinib may be useful for the treatment of some autoimmune skin diseases in dogs. Further controlled studies are needed to confirm our findings., (© 2017 ESVD and ACVD.)

Background: Bacterial pyoderma is a frequent presentation in dogs. Despite the widespread availability of effective systemic and topical antimicrobial products, good clinical practice currently recommends avoidance of long-term use to mitigate the development of bacterial resistance., Hypothesis/objectives: To evaluate the speed of resolution of clinical signs of bacterial pyoderma in dogs treated with a systemic antimicrobial agent with or without the use of an adjunctive spray with antimicrobial properties., Animals: Twelve dogs with superficial bacterial pyoderma., Methods: In this controlled and blinded study, all dogs were treated with oral cefalexin and a topical spray (PYOClean Spray) for 4 weeks. The spray was applied to one half of each dog's body, whereas a placebo spray was applied to the other half., Results: Twelve dogs completed the study. Mean clinical scores were significantly reduced on spray-treated sites, for test product and placebo (respectively), by 47% and 34% at Week 1, 83% and 60% at Week 2, 95% and 82% at Week 3, and 100% and 96% at Week 4. Fifty percent of treated sites were considered clinically and cytologically cured at Week 2, 83% at Week 3, and 100% at Week 4 compared to 8%, 50% and 83% for the placebo sites, respectively., Conclusions and Clinical Importance: These results demonstrate that use of a topical spray which contains plant-derived essential oils and fatty acids, and compounds with antimicrobial properties (Manuka oil and N-acetyl cysteine) may help to speed resolution of pyoderma and may allow for shorter antimicrobial treatment time., (© 2016 ESVD and ACVD.)

Background: Wipes containing chlorhexidine and azole derivates have been recommended for veterinary use. No study has been published about their activity against Malassezia pachydermatis., Hypothesis/objectives: To evaluate the in vivo and in vitro activity of wipes soaked in a chlorhexidine, climbazole and Tris-EDTA solution against Malassezia pachydermatis., Animals: Five research colony shar-pei dogs., Methods: Wipes were applied once daily onto the left axilla, left groin and perianal area (protocol A), and twice daily on the right axilla, right groin and umbilical region (protocol B) for 3 days. In vivo activity was evaluated by quantifying Malassezia colonies through contact plates on the selected body areas before and after wipe application. The activity of the solution in which the wipes were soaked was assessed in vitro by contact tests following the European Standard UNI EN 1275 guidelines., Results: Samples collected after wipe application showed a significant and rapid reduction of Malassezia yeast CFU. No significant difference in the Malassezia reduction was found between protocols A and B. In vitro assay showed 100% activity against Malassezia yeasts after a 15 min contact time with the wipe solution., Conclusions and Clinical Importance: Wipes containing chlorhexidine, climbazole and Tris-EDTA substantially reduced the M. pachydermatis population on the skin of dogs. The results, although this was an uncontrolled study performed on a small number of dogs, suggest that these wipes may be useful for topical therapy of Malassezia dermatitis involving the lips, paws, perianal area and skin folds., (© 2015 ESVD and ACVD.)

Background: Angiostrongylus vasorum is a nematode that primarily infects Canidae. The adult parasites are found in the pulmonary arterial circulation and the right side of the heart. The most common clinical sign is respiratory dysfunction. Bleeding, neurological, ocular, cardiovascular and gastrointestinal disorders are also reported. Skin lesions are very unusual., Hypothesis/objectives: This report describes a nematode dermatitis due to A. vasorum infection. To the best of the authors' knowledge, this is the first case of a dog infected with this parasite that initially presented with skin lesions only., Animal: A 3-year-old female Weimaraner dog presented with a crusted papular dermatitis on the bridge of the nose and on the pinnae, and an erythematous pododermatitis with erosions and perionyxis of one digit of 1 week's duration. Two weeks later the dog developed respiratory distress., Methods and Results: Skin scrapings and fungal culture were negative for parasites and dermatophytes. Histopathological examination showed dermal granulomas and pyogranulomas with eosinophils centred around parasitic elements compatible with nematode larvae. Angiostrongylus vasorum DNA was demonstrated in skin biopsies. Chest radiographs were compatible with verminous pneumonia and a Baermann test revealed A. vasorum larvae. The dog was treated orally with fenbendazole, with rapid improvement and complete cure after 3 months., Conclusions and Clinical Importance: Angiostrongylus vasorum should be considered in dogs presented with skin lesions and respiratory signs. Skin biopsy, chest radiographs and Baermann test should be included in the diagnostic investigation., (© 2015 ESVD and ACVD.)

Background: The lack of an accepted clinical scoring system in canine otitis externa makes it difficult to compare clinical trials., Hypothesis/objectives: To develop a score that is clinically relevant, reliable and sensitive to change., Animals: Client-owned healthy dogs (n = 55) and dogs with otitis externa (n = 60)., Methods: We compared 0-3 and 0-5 assessments of erythema, oedema/swelling, erosion/ulceration, exudate and pain of the ear canals with a reference 0-2 scale. Additional data included odour, pruritus scores, tympanic membrane condition, treatment outcome and neutrophil, bacterial and Malassezia counts., Results: There were no significant differences between the vertical and horizontal canal scores (correlation coefficients >0.93). Correlation coefficients for the 0-3 and 0-5 scales were also >0.9 for all parameters, but the 0-2 scale was more variable. Pain and pruritus did not correlate well with the lesion scores and were associated with suppurative and erythroceruminous otitis, respectively. Neutrophil and microbial counts were variable and could not be used to generate cut-off values to differentiate healthy and affected ears or determine the response to therapy. Total scores ≥4 differentiated affected from healthy ears with 91.1% sensitivity and 100% specificity; scores ≤3 were 100% sensitive and 91.9% specific for clinical success. The intra- and interobserver reliability was high (intraclass correlation coefficients >0.95 and Cohen's kappa coefficients >0.65)., Conclusions and Clinical Importance: This pilot study showed that the 0-3 Otitis Index Score (OTIS3) for erythema, oedema/swelling, erosion/ulceration and exudate is suitable for further validation by a larger group of clinicians., (© 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: A randomized, unmasked, multicenter study was conducted to evaluate the rate of pruritus reduction and improvement in clinical scoring by cyclosporine A (5 mg/kg orally, once daily for 28 days) either alone (n = 25 dogs) or with concurrent prednisolone (1 mg/kg once daily for 7 days, followed by alternate dosing for 14 days; n = 23 dogs) for the treatment of atopic dermatitis in dogs. Dogs were included in the study after exclusion of other causes of pruritic dermatitis, and were assessed by dermatologists on days 0, 14 ± 1 and 28 ± 2. Assessments included: general physical examination, CADESI-03 lesion scoring, overall clinical response, evaluation of adverse events (AEs), body weight and clinical pathology (hematology, clinical chemistry and urinalysis). Owner assessments, including pruritus (visual analogue scale, VAS) and overall assessment of response were conducted every 3-4 days, either during visits to the clinic or at home. Owners reported AEs to the investigator throughout the study., Results: By day 28 ± 2 both treatment groups resulted in a significant improvement of the atopic dermatitis. Both investigators and owners agreed that concurrent therapy resulted in a quicker improvement of the dogs 'overall' skin condition and of pruritus (significant reduction of pruritus by day 3-4, 72.8% improvement by day 14 ± 1), when compared to cyclosporine A alone (significant reduction of pruritus by day 7-8, 24.7% improvement by day 14 ± 1). CADESI-03 scores significantly improved in both groups by day 14 ± 1 onwards, and there were no significant differences in the scores between treatment groups at any time points. A total of 56 AEs (cyclosporine A alone = 34; concurrent therapy = 22) were reported in 33 dogs. No dogs died or stopped treatment due to an AE. The most commonly reported AEs in the cyclosporine A group were associated with the digestive tract, whilst systemic disorders were reported more frequently observed following concurrent therapy. Evaluation of body weight change and clinical pathology indices showed no overall clinically significant abnormalities., Conclusions: In dogs with atopic dermatitis, a short initiating course of prednisolone expedited the efficacy of cyclosporine A in resolving pruritus and associated clinical signs. The observed adverse events were consistent with those expected for the individual veterinary medicinal products.

Background: Cutaneous infections with bacteria and yeasts are common in small animal practice. Treatment with systemic antibiotics or antifungal agents may not be ideal, because of the increasing development of multiresistant organisms, the cost and the possible adverse effects. Topical antimicrobials may be used as adjunctive therapy to systemic treatment or as sole therapy instead of systemic treatment., Objective: This literature review evaluated studies on topical antimicrobial treatment of skin infections., Methods: In vitro and in vivo studies evaluating topical antimicrobial agents were identified using a number of electronic and manual searches of textbooks and articles. Studies were evaluated, and the evidence for or against the use of the topical agents was extracted., Results: There is good evidence for the efficacy of chlorhexidine and, to a lesser degree, benzoyl peroxide in canine bacterial skin infections. There is limited evidence for the efficacy of silver sulfadiazine and medical honey against bacterial skin infections in the dog, and for the efficacy of hydrogen peroxide and stannous fluoride in the horse. Good evidence supports the use of a combination of chlorhexidine and miconazole in dogs with cutaneous Malassezia infections. There is insufficient evidence to recommend any other topical therapy for use in cutaneous infections., Conclusions and Clinical Importance: Although many antimicrobial topicals are marketed in veterinary dermatology, the efficacy has been reported for only a minority of agents. Randomized controlled trials evaluating various topical treatments are therefore urgently needed., (© 2012 The Authors. Veterinary Dermatology © 2012 ESVD and ACVD.)

Background and Objectives: These guidelines were written by an international group of specialists with the aim to provide veterinarians with current recommendations for the diagnosis and treatment of canine demodicosis., Methods: Published studies of the various treatment options were reviewed and summarized. Where evidence in form of published studies was not available, expert consensus formed the base of the recommendations., Results: Demodicosis can usually be diagnosed by deep skin scrapings or trichograms; in rare cases a skin biopsy may be needed for diagnosis. Immune suppression due to endoparasitism or malnutrition in young dogs and endocrine diseases, neoplasia and chemotherapy in older dogs are considered predisposing factors and should be diagnosed and treated to optimize the therapeutic outcome. Dogs with disease severity requiring parasiticidal therapy should not be bred. Secondary bacterial skin infections frequently complicate the disease and require topical and/or systemic antimicrobial therapy. There is good evidence for the efficacy of weekly amitraz rinses and daily oral macrocyclic lactones such as milbemycin oxime, ivermectin and moxidectin for the treatment of canine demodicosis. Weekly application of topical moxidectin can be useful in dogs with milder forms of the disease. There is some evidence for the efficacy of weekly or twice weekly subcutaneous or oral doramectin. Systemic macrocyclic lactones may cause neurological adverse effects in sensitive dogs, thus a gradual increase to the final therapeutic dose may be prudent (particularly in herding breeds). Treatment should be monitored with monthly skin scrapings and extended beyond clinical and microscopic cure to minimize recurrences., (© 2012 The Authors. Veterinary Dermatology. © 2012 ESVD and ACVD.)

This study compared the efficacy of a 0.0584% hydrocortisone aceponate (HCA) spray (Cortavance(®); Virbac SA) and ciclosporin (Atopica(®); Novartis Animal Health) in canine atopic dermatitis in a single-blind randomized controlled trial. Dogs received HCA (two sprays/100 cm(2); n=24) or ciclosporin (5 mg/kg; n=21). Canine Atopic Dermatitis Extent and Severity Index (CADESI)-03, pruritus (visual analog scale with grade descriptors) and owner scores (5-point scales) were recorded every 28 days for 84 days. Intention-to-treat data were analysed. CADESI-03 and pruritus significantly decreased over time (P<0.0001), but there was no difference between the treatment groups (P=0.91 and P=0.52, respectively). Similar proportions of HCA- and ciclosporin-treated dogs achieved ≥50% reductions in CADESI-03 and pruritus scores at 28 days (CADESI-03 58.3 and 57.1%, P=0.76; pruritus 33.3 and 38.1%, P=1.0), 56 days (CADESI-03 70.8 and 81.0%, P=1.0; pruritus 62.5 and 57.1%, P=1.0) and 84 days (CADESI-03 75 and 85.7%, P=0.72; pruritus 65.2 and 57.1%, P=0.76). The CADESI-03 and pruritus scores were close to equivalence (0.47 and 0.51, respectively). By 84 days, every-other-day or twice-weekly therapy was achieved in 13 of 24 HCA- and 12 of 21 ciclosporin-treated dogs (P=0.85). There were no significant differences in scores for efficacy (P=0.82), tolerance (P=0.62) and ease of administration (P=0.25). Scores for tolerance (0.49) and administration (0.46) were close to equivalence. The score for efficacy favoured HCA (0.68). Mild adverse events were noted in six of 21 ciclosporin and none of 24 HCA dogs (P=0.008). Five HCA-treated dogs and three ciclosporin-treated dogs were prematurely withdrawn (P=0.7). In conclusion, HCA and ciclosporin proved equally effective in treating canine atopic dermatitis for up to 84 days., (© 2011 The Authors. Veterinary Dermatology © 2011 ESVD and ACVD.)

Ichthyoses comprise a heterogeneous group of genodermatoses characterized by abnormal desquamation over the whole body, for which the genetic causes of several human forms remain unknown. We used a spontaneous dog model in the golden retriever breed, which is affected by a lamellar ichthyosis resembling human autosomal recessive congenital ichthyoses (ARCI), to carry out a genome-wide association study. We identified a homozygous insertion-deletion (indel) mutation in PNPLA1 that leads to a premature stop codon in all affected golden retriever dogs. We subsequently found one missense and one nonsense mutation in the catalytic domain of human PNPLA1 in six individuals with ARCI from two families. Further experiments highlighted the importance of PNPLA1 in the formation of the epidermal lipid barrier. This study identifies a new gene involved in human ichthyoses and provides insights into the localization and function of this yet uncharacterized member of the PNPLA protein family.