Veterinary dermatology最新文献

Background: Canine reactive histiocytosis is a proliferative disorder of activated interstitial dendritic cells with cutaneous and systemic forms. An immune-mediated aetiology is likely, and systemic immunomodulatory agents such as corticosteroids, tetracycline/niacinamide, ciclosporin, azathioprine and leflunomide have been employed for its management.

Hypothesis/objectives: The aim of this retrospective case series is to report the clinical features and therapeutic response to oclacitinib in dogs with reactive histiocytosis.

Animals: Ten privately owned dogs.

Materials and methods: All dogs were diagnosed with reactive histiocytosis based on compatible clinical history, skin lesions and histopathological features, and were treated with oclacitinib as a sole therapy. Immunohistochemical investigation was used to characterise dermal cellular infiltrates for eight of 10 dogs. Clinical features and case outcomes are summarised.

Results: All 10 dogs presented with dermal nodules and/or erythematous plaques affecting the head, trunk or limbs; four dogs also had documented or suspected involvement of the nasal or oral cavities. Seven dogs had been treated previously with one or more immunomodulatory agents without durable disease control. All dogs were completely responsive to treatment with oclacitinib, at or slightly above the standard antipruritic dosage. Skin and mucosal lesions resolved within 2-12 weeks. Lesion remission was maintained with oclacitinib monotherapy for varying follow-up times, although four dogs had brief recurrences addressed with adjustments in oclacitinib dosing.

Conclusions and clinical relevance: Although reactive histiocytosis can have a naturally waxing and waning course, oclacitinib appears to be rapidly effective for management, even in cases refractory to other immunomodulatory agents or with involvement of the oral or nasal cavities.

Animal use statement: Animal use was conducted in accordance with the international, national and institutional guidelines for the humane treatment of animals, and with relevant legislation.

A 9-year-old gelding Quarter Horse with a lesion on the right upper eyelid was diagnosed with cutaneous lupus erythematosus. Clinical resolution and control of UV-induced flares were achieved with topical tacrolimus and a UV-blocking mask without adverse effects over the following 3 years.

Background: Advances in transcriptomics have driven the demand for minimally invasive, reproducible and high-yield skin sampling methods, particularly for studying inflammatory skin diseases in companion animals.

Hypothesis/objectives: We tested tolerability, feasibility and RNA quantity and quality of three minimally invasive skin sampling techniques.

Animals: Nine privately-owned dogs, including healthy individuals and those diagnosed with canine atopic dermatitis.

Materials and methods: The tolerability and feasibility of three minimally invasive skin sampling techniques-microbiopsy (MB) collection, skin-scraping (SS) and tape-stripping (TS)-were tested in a clinical setting. RNA quantity and quality (RIN) were measured. Quality control and potential contamination were evaluated during downstream RNA sequencing.

Results: All techniques were well-tolerated, and sampling was feasible in a clinical setting. RNA yield and quality varied significantly. Microbiopsy and SS samples yielded low RNA quantities with poor integrity. Tape-stripping samples produced the highest RNA concentration and integrity (RIN 3.4-7.1) yet showed notable variability. Although initial sequencing quality thresholds were met, downstream transcriptomic analysis of the TS samples was limited by uneven degradation and suspected DNA contamination.

Conclusions and clinical relevance: Minimally invasive skin sampling methods are feasible and well-tolerated in dogs. Among the techniques evaluated, TS showed the most potential for transcriptomic applications. However, RNA quality remains a key limitation. Further refinement in sample processing and handling is essential to improve consistency and enable reliable downstream analyses in veterinary dermatological research.

Background: Maropitant citrate (Cerenia; Zoetis) is a neurokinin-1 receptor antagonist that inhibits binding of substance P, and is approved to prevent acute emesis and motion sickness in dogs. Maropitant is often administered before sedation with α2-agonists to reduce the risk of vomiting. Many medications interfere with intradermal test (IDT) results and it is unknown if maropitant citrate alters IDT reactivity.

Objective: To assess the influence of maropitant citrate on IDT reactivity in dogs with canine atopic dermatitis (cAD).

Materials and methods: Twenty client-owned dogs with cAD were enrolled in a randomised, controlled, blinded, comparative trial. Each IDT was read independently by a dermatology resident and a referral clinician. Subjective (0-4) and objective (mm diameter) wheal scores were measured 15 min after intradermal injections. Four positive pollen allergens with established irritancy threshold concentrations (ITC) were selected for assessment in the next phase. Following completion of the initial IDT, maropitant citrate (1 mg/kg) was administered intravenously. A second, randomised, blinded IDT was performed using the four positive allergens injected in triplicate, with controls injected in duplicate.

Results: Histamine (objective mean difference [MD] = 1.1 mm, p = 0.01) and positive allergen (objective MD = 0.4 mm, p = 0.007; subjective MD = 0.2 mm, p < 0.001) wheal sizes were statistically larger post-maropitant citrate. The proportions of positive allergen scores were not significantly different pre- and post-maropitant citrate (objective: 48 of 80 pre- vs. 56 of 80 post-, p = 0.09; subjective: 80 of 80 pre- vs. 77 of 80 post-, p = 0.25). No adverse events were observed.

Conclusions and clinical relevance: Intravascular maropitant citrate increases wheal size, yet the effect on allergen selection for clinical treatment remains equivocal.

Background: Ichthyosis fetalis (IF), also known as harlequin ichthyosis, is a rare and often fatal autosomal recessive congenital skin disorder. It is characterized by thickened, hard skin plaques and deep skin fissures that limit mobility and cause malformations of the eyes, lips and ears. Affected individuals are highly susceptible to life-threatening infections due to the disruption of the skin's protective barrier. To date, IF and its genetic basis have not been described in domestic cats.

Objectives: To characterize the gross clinical, histopathological and genetic features of IF in two stray, random-bred domestic short-hair (DSH) littermates.

Animals: Two deceased female neonatal DSH kittens, both exhibiting sparse hair and deep fissures exposing the underlying dermis. One unrelated neonatal kitten with normal skin and hair was included as a control for comparison, along with 140 feline population samples from unrelated domestic cats of various breeds.

Materials and methods: Gross clinical examination, histopathological analysis, whole-genome sequencing and population genotyping were performed.

Results: Gross clinical and histopathological evaluations confirmed a diagnosis of IF in both affected kittens. Genetic analysis identified a homozygous one base pair deletion in ABCA12, resulting in a frameshift and predicted loss of function of the encoded protein. Genotyping of 140 unrelated cats revealed that all were homozygous for the wild-type allele.

Conclusions and clinical relevance: Variants in ABCA12 have been implicated previously in IF in humans, cattle and mice. This study provides the first description of IF in domestic cats and identifies a pathogenic ABCA12 frameshift variant as the likely genetic cause.

Background: Canine atopic dermatitis (cAD) is a multifactorial, inherited skin disease, estimated to affect ≤ 15% of dogs. Studies of skin messenger mRNA in cAD currently use invasive methods, including blood sampling and biopsy collection, whilst advances in human atopic dermatitis study methodology have demonstrated reliable use of minimally invasive skin sampling techniques for similar objectives.

Objectives: To validate the use of the minimally invasive D-Squame (tape stripping; TS) method for skin mRNA analysis in dogs, and to investigate the association of highly dysregulated mRNAs with clinical response in a canine model of cAD.

Animals: Eight healthy beagles.

Materials and methods: Dogs were epicutaneously sensitised twice weekly for 7 weeks (49 days) using house dust mites (HDM; Dermatophagoides farinae). The clinical response of individual dogs to sensitisation was categorised as low, average, or high. On Day 49, D-Squame TS samples were obtained from sensitised and nonsensitised sites from each dog, and transcriptomic analyses were performed. RNA-Seq data analyses were performed using R and Bioconductor with default parameters.

Results: Comparing sensitised and control sites, 210 of 12,545 expressed genes were most differentially expressed (fold-change ≥ 2, p ≤ 0.05). CD2, CD3D/E, CD209 (T cell), IL13, TNFRSF4, CCL17 (T helper 2 cell [Th2]), FCER1A and CD80 (dendritic cells) were among the top 50 most dysregulated genes significantly correlating with sensitisation. Dysregulation of several key mRNAs, including those involved in the Th2 pathway, correlated with clinical response.

Conclusions and clinical relevance: This proof-of-concept study using a minimally invasive method to investigate skin mRNA in cAD lesions enables ethical research of immune biomarkers involved in cAD.

Background: Gabapentin reportedly decreases central sensitisation, a disorder associated with chronic pruritus in humans, although this is not well documented in cats. Its combined use with the standard antipruritic therapy for feline atopic skin syndrome (FASS) is not yet described.

Objectives: To evaluate the impact of prednisolone, ciclosporin or placebo, with or without gabapentin, on lesional scores and actimetry in FASS cats.

Animals: Twenty-six cats from a laboratory colony with naturally acquired FASS.

Methods and materials: Following a 12-week washout period, cats were allocated to one of three groups: prednisolone (1 mg/kg, n = 9), ciclosporin (7 mg/kg, n = 8) and placebo (Avicel, n = 9). Treatments were administered orally, once daily for 5 weeks (Week [W]0 to W4), then combined with gabapentin (10-15 mg/kg) for another 3 weeks. The Feline Dermatitis Extent and Severity Index (FeDESI) was assessed at baseline and W2, W4 and W7. Actimetry was recorded and analysed over weekend (WE) time points. A repeated-measures generalised mixed model was applied using the zero-inflated negative binomial (FeDESI) or log-normal (actimetry) distribution (α = 0.05).

Results: Prednisolone alone significantly improved FeDESI (p = 0.008), while ciclosporin required the addition of gabapentin to achieve a significant effect (p < 0.034). Gabapentin decreased FeDESI scores in all groups (p < 0.001) and demonstrated the highest incidence rate ratio (2.59) compared to placebo. Improvements in FeDESI were associated with significant (corresponding in intensity) decreases in motor activity.

Conclusions and clinical relevance: Gabapentin, particularly when combined with prednisolone or ciclosporin, may reduce lesional score and actimetry-assessed itch in FASS cats, suggesting a potential central sensitisation in some cats.

Background: Administration of interleukin (IL)-31 to healthy dogs has been used in preclinical drug testing to evaluate the antipruritic effect of novel medications through a "preventative" design approach (i.e., drugs are given before IL-31 administration).

Hypothesis/objectives: Develop and validate a "reactive" intradermal IL-31-induced pruritus model in healthy dogs by administering oral oclacitinib.

Animals: Eight adult, healthy research-bred beagles.

Materials and methods: A blinded, randomised, cross-over study. All dogs received either intradermal recombinant canine IL-31 with or without a single dose of oral oclacitinib given afterward; cross-over treatment was administered following a 4-week washout period.

Results: Oclacitinib reduced the total (p = 0.0252) and local (p = 0.0078) pruritic behaviour seconds after intradermal IL-31 injections. It also reduced the total seconds of scratching (p = 0.0078), chewing/biting (p = 0.0078) and head-shaking (p = 0.0255) behaviours. No significant reduction in licking was observed. Decreases in total pruritic seconds in this "reactive" model following oclacitinib administration were observed at 120-180 min (p = 0.0058), 180-240 min (p = 0.0075) and 240-300 min (p = 0.0241). Likewise, decreases in local pruritic behaviour seconds were observed at 60-120 min (p = 0.0498) and 240-300 min (p = 0.0343).

Conclusions and clinical relevance: The study established the first "reactive" canine intradermal IL-31 itch model in healthy dogs. One-time oral administration of oclacitinib significantly reduced the incidence of pruritic behaviours. Novel antipruritic medications can be assessed and compared using this "reactive" model in future preclinical trials.

This report presents the clinical features, clinicopathological changes, computed tomography images and response-to-treatment of a dog with calcium-laden subcutaneous fluid collections, resembling a rare form of calcinosis in humans termed 'milk of calcium'.

Background: Suppurative Malassezia otitis externa (SMO) is a rare, severe presentation of Malassezia otitis (MO) sparsely reported in the literature.

Hypothesis/objectives: The primary objective of this study was to describe the clinical presentation, diagnostic findings, treatment, and prognosis of SMO. A secondary objective was to speciate available SMO isolates, as this phenotype may be caused by different Malassezia species.

Animals: Nine client-owned dogs with SMO.

Materials and methods: A retrospective study of medical records from nine dogs with SMO diagnosed at an academic referral hospital from 2022 to 2024. Three SMO and 10 MO isolates from poodle-crosses were speciated with matrix-assisted laser desorption and ionisation time-of-flight mass spectrometry (MALDI-TOF MS).

Results: Young (average 1-year-old), male (67%), poodle or poodle-crosses (67%; six of nine dogs) were most often affected. Clinical presentation included unilateral otitis externa (77%; seven of nine dogs) with dark brown mucoid discharge, canal ulceration, erythema and glandular hyperplastic changes (100%). Cytological findings included yeast, neutrophils, and extracellular material suggestive of biofilm (100%). Prior otic treatment was primarily misdirected towards Pseudomonas otitis. Malassezia pachydermatis was identified in two SMO isolates and half of the MO isolates. Prednisone (0.5-1 mg/kg/day) per os daily tapered over 1 month plus daily otic orbifloxacin, mometasone furoate monohydrate and posaconazole (Posatex; Merck Animal Health) achieved complete resolution in 83% of affected ears without an anaesthetised otic lavage. At the time of writing, there was no known recurrence of any case within at least 6 months of treatment.

Conclusions and clinical relevance: SMO is a phenotypically severe presentation of MO clinically mimicking suppurative bacterial otitis. Young, male poodle-crosses are commonly affected. Ear canal hair plucking is likely to incite severe primary inflammation before SMO development.