Uveodermatological syndrome associated with alopecia areata in a one-year-old female spayed Cavalier King Charles Spaniel dog.

Uveodermatological syndrome and alopecia areata are autoimmune disorders causing ocular and dermatological inflammation and alopecia, respectively, in dogs. This is the first report to document concurrent development of the two diseases in a dog, as has been reported in human patients. Clinical presentation and histopathological diagnosis, treatment and clinical follow-up are described.

Miliary osteoma cutis in a climbing mantella frog (Mantella laevigata).

A climbing mantella frog (Mantella laevigata) was presented with nodular thickened skin. Histological examination revealed dermal nodules composed of differentiated bone consistent with miliary osteoma cutis, a non-neoplastic condition where bone is abnormally deposited within the skin. This is the first report of idiopathic osteoma cutis in an amphibian.

Subcutaneous panniculitis-like T-cell lymphoma: Morphological, immunophenotypical and clonality assessment in six cats.

BACKGROUND: Primary cutaneous lymphoma represents 0.2%-3% of all feline lymphomas, with nonepitheliotropic lymphomas being the most common. In humans and dogs, subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a primary nonepitheliotropic lymphoma with a T-cell phenotype developing in the subcutis and often mimicking inflammation. OBJECTIVE: The aim of this report is to describe pathological, phenotypical and clonal features of SPTCL in cats. ANIMALS: Six cats with SPTCL were included in this study. MATERIALS AND METHODS: Skin biopsies were formalin-fixed, routinely processed and stained. Histological and immunohistochemical investigation for anti-CD18, CD204, CD79a, CD20, CD3, FeLVp27and FeLVgp70 and clonality assessment were performed. RESULTS: Four male and two female domestic shorthair cats, mean age 11.2 years, developed SPTCL in the abdominal (three), inguinal (two) and thoracic (one) regions. Variably pleomorphic neoplastic lymphoid cells were present in the panniculus in percentages, expanding the septa (six of six) and extending into fat lobules in one of six cats. Tumours were associated with elevated numbers of neutrophils (five of six), lesser macrophages (six of six) and variable necrosis (six of six). Neoplastic cells expressed CD3+ (six of six), with clonal T-cell receptor rearrangement detected in five of six cats. CONCLUSIONS AND CLINICAL RELEVANCE: This is the first description of SPTCL in cats. Lesions can be confused with panniculitis, leading to delay in diagnosis and therapy. Awareness of this neoplastic disease is relevant to avoid misdiagnoses and to gain greater knowledge about the disease in cats.

A multicentric intermediate-size B-cell lymphoma with epitheliotropism in a Freiberger mare.

This report describes a multicentric intermediate-size B-cell lymphoma with epitheliotropism in a Freiberger mare affecting multiple mucous membranes, skin and internal organs. The clonal neoplastic B-cell population was accompanied by numerous reactive polyclonal small T cells. Differential diagnoses for these unusual findings are discussed.

SOAT1 missense variant in two cats with sebaceous gland dysplasia.

Spontaneously arisen hereditary diseases in domestic animals provide an excellent opportunity to study the physiological functions of the altered genes. We investigated two 4-month-old sibling domestic short haired kittens with dry dark debris around the eyes, nose, and ears, dark crusting on the legs and a thin poor hair coat. Skin biopsies revealed abnormal sebaceous gland morphology with lack of normal sebocyte arrangement and differentiation. Hair follicles had a distorted silhouette, interpreted as a change secondary to the observed sebaceous gland dysplasia. Whole genome sequencing on both affected kittens and 65 genetically diverse feline genomes was performed. Filtering for variants that were present in both kittens but absent from the control genomes revealed a homozygous missense variant in SOAT1, encoding sterol O-acyltransferase 1. The protein is localized in the endoplasmic reticulum and catalyzes the formation of cholesteryl esters, an essential component of sebum and meibum. The identified SOAT1:c.1531G > A variant is predicted to change a highly conserved glycine residue within the last transmembrane domain of SOAT1, p.Gly511Arg. In mice, variants in Soat1 or complete knockout of the gene lead to the "hair interior defect" (hid) or abnormal Meibomian glands, respectively. SOAT1:c.1531G > A represents a plausible candidate variant for the observed sebaceous gland dysplasia in both kittens of this study. The variant was not present in 10 additional cats with a similar clinical and histopathological phenotype suggesting genetic heterogeneity. SOAT1 variants should be considered as potential cause in hereditary sebaceous gland dysplasias of humans and domestic animals.

Polyautoimmunity manifest as inflammatory myopathy, uveitis, and progressive cutaneous depigmentation in a mixed breed dog: a case report.

BACKGROUND: Polyautoimmunity is the expression of more than one autoimmune disease in a single patient. This report documents polyautoimmunity in a mixed breed dog with concurrent uveitis, cutaneous depigmentation, and inflammatory myopathy. CASE PRESENTATION: A 1-year-old male neutered mixed breed dog was presented for progressive generalized leukotrichia and leukoderma, bilateral panuveitis, and masticatory muscle atrophy. The latter progressed to myositis of lingual, pharyngeal, and masticatory muscles confirmed by biopsy. Temporalis muscle was completely replaced by adipose and fibrous tissue, and necrotic myofibers with extensive infiltration of mononuclear cells indicated active myositis of lingual muscle. Skin biopsies showed severe melanin clumping in epidermis, hair follicles, and hair shafts, and perifollicular pigmentary incontinence. Uveitis, depigmentation, and myositis affecting the masticatory, pharyngeal, and tongue muscles were diagnosed based on clinical, histological, and laboratory findings. CONCLUSIONS: To the authors' knowledge, this is the first report of concurrent uveitis, progressive cutaneous depigmentation, and inflammatory myopathy in a dog.

Cytotoxic dermatitis: Review of the interface dermatitis pattern in veterinary skin diseases.

Interface dermatitis or lichenoid interface dermatitis refers to a cutaneous inflammatory pattern in which keratinocyte cell death is the essential feature. These terms have evolved from the originally described lichenoid tissue reaction. These lesions are the basis for an important group of skin diseases in animals and people where cytotoxic T-cell-mediated epidermal damage is a major pathomechanism. Yet, for largely historical reasons these commonly used morphological diagnostic terms do not reflect the essential nature of the lesion. An emphasis on subsidiary lesions, such as the presence of a lichenoid band, and definitions based on anatomical features, such as location at the dermo-epidermal location, may cause confusion and even misdiagnosis. This review covers historical aspects of the terminology, including the origin of terms such as "lichenoid." The types of cell death involved and the histopathologic lesions are described. Etiopathogenesis is discussed in terms of aberrations of immune/inflammatory mechanisms focusing on cutaneous lupus erythematosus, erythema multiforme, and Stevens-Johnson syndrome/toxic epidermal necrolysis. Mechanisms have most extensively been studied in humans and laboratory animals and the discussion is centered on these species. As interface dermatitis is firmly entrenched in dermatological parlance, rather than using "cytotoxic" as its substitute, the terminologies "interface cytotoxic dermatitis" and "panepidermal cytotoxic dermatitis" are recommended, based on location and extent of epithelium affected.

Pattern analysis for the diagnosis of inflammatory skin lesions in domestic animals: An overview.

Pattern analysis of inflammatory skin diseases is a technique that offers a systematic approach to the histologic diagnosis of skin diseases. First introduced to human dermatopathology in the 1970s, it was widely adopted by veterinary pathologists for the histologic diagnosis of skin diseases in animals. As the inflammatory pattern reflects, to varying extents, aspects of the underlying disease pathogenesis, its use has contributed to the recognition of novel skin diseases in domestic animals, particularly in dogs and cats. Alternative diagnostic approaches used in human dermatopathology, such as "tissue-reaction pattern" and a purely "anatomic approach" have not been as widely used in veterinary pathology. However, veterinary pathologists often combine pattern analysis with anatomic and etiologic factors. This overview outlines the technique, introduces the patterns, and discusses advantages and limitations of pattern analysis in veterinary diagnostic dermatopathology. While molecular analytic techniques and image informatics will undoubtedly prove to be revolutionary in many areas of diagnostic pathology, it is recognized in both human and veterinary arenas that the light microscopic interpretation of hematoxylin and eosin-stained tissue sections will remain the mainstay of routine dermatopathology diagnosis for the foreseeable future.

Odontogenic-like neoplasms of the rabbit cheek: pathological features and comparison to cutaneous trichoblastoma and jaw-associated ameloblastoma.

Odontogenic neoplasms demonstrate unique histopathological features and are thought to arise from the germinal tissues of the developing tooth germ, effectively restricting their anatomic origin to the tooth-bearing regions of the jaw and directly associated soft tissues of the oral cavity. Ectopic odontogenic-like neoplasms located in the skin of cats, rabbits, and human beings challenge these assumptions. Here we describe the clinical, pathological, and immunohistochemical features of 6 spontaneously occurring odontogenic-like neoplasms arising in the cutaneous tissue of the cheek in client-owned pet rabbits, including ameloblastoma-like (n = 3), ameloblastic fibroma-like (n = 2), and ameloblastic carcinoma-like neoplasms (n = 1). Microscopically, all the cheek tumors featured neoplastic epithelium exhibiting odontogenic architectural structures (plexiform ribbons, anastomosing trabeculae, follicles, cysts, and irregular structures with rounded botryoid protuberances) and 1 or more cardinal odontogenic epithelial features (basal palisading, antibasilar nuclei, and central stellate reticulum-like cells). The pancytokeratin, cytokeratin 5/6, cytokeratin 14, and vimentin immunohistochemical patterns of these odontogenic-like lesions were most similar to those of jaw-associated ameloblastoma and differed from those of cutaneous trichoblastoma. All neoplasms were narrowly excised, and for lesions with clinical follow-up information, none had evidence of recurrence 1-7 months after surgical removal. Although evidence suggests that these odontogenic-like tumors of the rabbit cheek may be derived from ectopic rests of transformed tooth germ, the histogenesis of these lesions remains unresolved.

Evaluation of aural masses submitted as inflammatory polyps in 20 dogs (2000-2020).

BACKGROUND: Canine non-neoplastic aural polypoid masses (APMs) are uncommon, with few published studies. OBJECTIVES: The aim of this retrospective study was to characterise the clinical presentation, diagnostic imaging and histopathological results for APMs submitted as aural inflammatory polyps (AIPs). ANIMALS: Twenty dogs with APMs evaluated at a veterinary teaching hospital. MATERIALS AND METHODS: Cases were selected by searching computerised medical records from 2000 to 2020, using keywords 'canine', 'aural/otic polyp' and 'aural/otic inflammatory mass'. Histological samples and medical records were reviewed. RESULTS: In 14 of 20 dogs, external ear canal masses were characterised by keratinised squamous epithelium with or without adnexa. Tympanic bulla origin was confirmed in four of 20 dogs by the presence of cuboidal to ciliated columnar epithelium, with or without squamous epithelium. The site of origin could not be determined in two dogs. Diagnostic imaging (MRI or CT) confirmed APM presence in 14 of 20 dogs. Otitis media was diagnosed in four of four tympanic bulla APMs and seven of 13 ear canal APMs. In 18 of 20 dogs, debulking, traction avulsion, and total ear canal ablation and bulla osteotomy led to APM resolution in two of eight, four of six and four of four dogs, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Type of epithelium was a key feature in determining the APM origin, and interpretation in conjunction with video otoscopy and diagnostic imaging was crucial. Canine APMs more commonly arose from the ear canal. Tympanic bulla APMs and APMs of undetermined origin were comparable to feline AIPs. Regardless of APM origin site, debulking had the greatest likelihood of recurrence.

Distribution of canine distemper virus and nectin-4 in raccoon (Procyon lotor) skin.

Raccoons (Procyon lotor) are abundant in urban/wildland interfaces and are key sources of canine distemper virus (CDV) outbreaks in domestic, zoo, and free-ranging wildlife species. CDV is pantropic, which provides multiple potential routes of transmission (urine, respiratory secretions, feces), but the specific role of skin as a target of infection, as a diagnostic sample, or as a potential source of environmental persistence and transmission is unknown. We have characterized the distribution of CDV and its known receptor, nectin-4, in skin samples of 36 raccoons. Even with skin samples that were grossly and histologically normal, immunohistochemistry of skin was useful in the diagnosis of CDV infection, which was found in both epithelium and endothelium. Nectin-4 was codistributed with cellular targets of viral infection. Skin secretions, shed keratinocytes, and hair of CDV infected raccoons are all potential environmental fomites.

Retrospective case series: Necrotising fasciitis in 23 dogs.

BACKGROUND: Necrotising fasciitis (NF) is a rare, rapidly progressive subcutaneous bacterial infection. Few studies have characterised NF in dogs. HYPOTHESIS/OBJECTIVES: To retrospectively describe clinical and laboratory findings, with treatments and outcomes, in dogs with NF. ANIMALS: Twenty-three client-owned dogs treated at a veterinary teaching hospital between 1998 and 2021. MATERIALS AND METHODS: Medical records and laboratory data from 23 dogs diagnosed with NF were reviewed. RESULTS: Male dogs were significantly over-represented (p = 0.003). The most common presenting complaint was sudden lameness. Infection occurred in one or two limbs in 19 of 23 dogs, with right hindlimbs most often affected (13 of 23). Pitting oedema was evident in 14 of 23 dogs. Antibiotic and nonsteroidal anti-inflammatory drugs were administered before presentation in nine and 13 of 23 dogs, respectively. Common clinicopathological abnormalities included hypoalbuminemia, hyponatremia, elevated liver enzymes, elevated creatine kinase, increased bands and lymphopenia. Streptococcus canis was isolated from 18 of 23 dogs. Histopathological features included acute necrosis and severe neutrophilic inflammation. Fifteen dogs were euthanised or died, while surgical intervention led to survival in eight of 23 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Dogs presenting for acute swelling of a limb with oedema should have the diagnosis of NF considered and early surgical intervention might increase survival.

Locally extensive follicular hamartomas with concurrent follicular cysts and dermoid cysts on the head of a dog.

A 5-month-old, male intact Australian shepherd dog was presented with nodular lesions affecting the dorsal head. A locally diffuse form of follicular hamartomas, with concurrent dermoid cysts and follicular cysts, was diagnosed by histopathological examination. Complete surgical excision of the affected skin and closure with a subdermal plexus advancement flap led to long-term resolution.

Un berger australien mâle intact âgé de 5 mois a été présenté avec des lésions nodulaires affectant la face dorsale de la tête. Une forme localement diffuse d'hamartomes folliculaires, avec des kystes dermoïdes et des kystes folliculaires concomitants, a été diagnostiquée par examen histopathologique. L'éxérèse chirurgicale complète de la peau atteinte et la fermeture avec un lambeau d'avancement du plexus sous-cutané ont conduit à une résolution à long terme.

Un perro pastor australiano macho entero de 5 meses de edad se presentó con lesiones nodulares que afectaban el dorso de la cabeza. Mediante examen histopatológico se diagnosticó una forma localmente difusa de hamartomas foliculares, con quistes dermoides y quistes foliculares concurrentes. La escisión quirúrgica completa de la piel afectada y el cierre con una zona avanzada en colgajo del plexo subdérmico condujo a una resolución a largo plazo.

Skin disease in goats (Capra aegagrus hircus): a retrospective study of 358 cases at a university veterinary teaching hospital (1988-2020).

BACKGROUND: Goats are important worldwide as a source of milk, meat, fibre and hide, and as show animals and pets. HYPOTHESIS/OBJECTIVES: To document the type, signalment associations and prevalence of skin disease in a referral hospital population. ANIMALS: Case population at a university veterinary teaching hospital. METHODS AND MATERIALS: Retrospective study by searching computerised medical records of goats seen between 1 January 1988 and 1 January 2021. Key words employed were "alopecia, caseous lymphadenitis, Chorioptes, dermatitis, dermatophyte, dermatophytosis, goat, lice, louse, mange, mite, pemphigus foliaceus, Psoroptes, ringworm, seborrhea, skin" RESULTS: Of 1,488 records reviewed, 358 (24%) goats had skin disease recorded. Seventy-nine (22.1%) of 358 goats presented primarily for skin disease. The Nigerian Dwarf goat breed was at higher risk of developing skin disease (P < 0.0002). As goats aged, the odds for developing skin disease was higher [odds ratio (OR) = 1.07 per year, 95% confidence interval (1.04, 1.12)] as was the predilection for malignant skin tumours (P < 0.001). Sex was not associated with skin disease (P = 0.98). The most common clinical sign was exfoliative dermatitis, noted in 94 (26.4%) of 358 goats. The most common diagnoses were pediculosis, bacterial skin disease and squamous cell carcinoma. Less frequent diagnoses were Chorioptes spp. infestation, contagious ecthyma (orf), coronitis/interdigital dermatitis, demodicosis, dermatophytosis, Psoroptes spp. infestation, dermatophilosis and pemphigus foliaceus. CONCLUSIONS AND CLINICAL IMPORTANCE: Skin diseases are common in goats. Nigerian Dwarf goats and older goats are at greater risk of developing skin disease; Nigerian Dwarf goats had a predilection for malignant skin tumours. Clinicians should include a dermatological examination in goats regardless of the reason for presentation.

Demodectic mange in threatened southern sea otters (Enhydra lutris nereis).

BACKGROUND: Southern sea otters (Enhydra lutris nereis) rely on intact pelage for thermoregulation, and thus clinically significant demodicosis and associated alopecia can cause morbidity and death. HYPOTHESIS/OBJECTIVES: This study aimed to describe lesions associated with follicular Demodex sp. infestation, estimate the prevalence and intensity of infestation, describe mite distribution across key anatomical regions, and assess mite presence or absence in relation to lesions and host risk factors. ANIMALS: Twenty necropsied, wild southern sea otters that stranded along the central California coast from 2005 to 2018. METHODS AND MATERIALS: Grossly normal and abnormal integument from the head, perineum, genitals, mamillary papillae and limbs was assessed microscopically for mites and mite-associated pathological findings. RESULTS: Intrafollicular mites were observed in the integument of 55% of otters and 20% had clinical demodicosis. Demodicosis was considered to be contributory to death or euthanasia in two cases. Although Demodex sp. mites often were observed microscopically in grossly normal skin, the presence of multiple densely-packed intrafollicular mites generally was associated with pigmentary incontinence, ectatic follicles, lymphoplasmacytic perifolliculitis, and neutrophilic and lymphoplasmacytic, dermal inflammation. Other findings included epidermal hyperplasia, orthokeratotic hyperkeratosis of epidermis and follicular epithelium, concurrent pyoderma and cell necrosis. Perioral integument, especially of the chin, had the highest prevalence of mites and the highest mite density, suggesting facial contact as a means of mite transmission. CONCLUSIONS AND CLINICAL IMPORTANCE: Our research confirmed demodectic mange as a contributor to morbidity and mortality in sea otters, with important implications for clinical care, rehabilitation and conservation.

Multicentric B-cell lymphoma with presumed paraneoplastic generalized cutaneous sclerosis in a dog.

BACKGROUND: Reports of dermal sclerosis in dogs include scleroderma or morphea of unknown cause, cicatricial alopecia and congenital/hereditary fibrosis. CLINICAL SUMMARY: A 12-year-old, male castrated chihuahua-mix dog was evaluated for skin lesions of unknown duration. The dog had severe alopecia, skin thickening and marked peripheral lymphadenopathy. Lymph node cytological investigation, immunohistochemical investigation and clonality testing demonstrated an intermediate to large B-cell lymphoma. The thickened skin had severe collagen deposition, effacing adnexal structures. The dog's lymphoma was treated but the skin lesions remained unchanged. The dog was euthanized. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first report of multicentric B-cell lymphoma in a dog with concurrent diffuse cutaneous sclerosis, similar to a human paraneoplastic reaction.

A case of atypical multifocal nodular eosinophilic dermatosis in a Labrador retriever dog.

BACKGROUND: A dog with gastrointestinal signs and a history of administration of multiple drugs developed acute multifocal to coalescing ulcerative nodules and a large plaque. OBJECTIVE: To describe abnormal nodular clinical lesions with an unexpected superficial and deep severe eosinophilic perivascular to interstitial inflammation. ANIMAL: A 7-year-old spayed female Labrador retriever METHODS AND MATERIALS: Blood tests, faecal and urinalysis, and abdominal radiographs were performed; skin biopsy samples were taken for cytological, culture and histopathological analyses. RESULTS: The blood tests, faecal, urinalysis and radiographs were within normal limits. Cytological results revealed inflammatory cells and cultures had no growth. Histopathological evaluation revealed dermal and subcutaneous oedema, mucin deposition and perivascular to interstitial inflammation predominated by eosinophils with occasional very small intralesional dense aggregates of eosinophils centred on collagen bundles, eosinophilic exocytosis and small eosinophilic pustules. Focal subepidermal fibrin exudation and haemorrhage resulted in epidermal detachment and ulceration. Clinical resolution of the dermatological and gastrointestinal signs was seen with the withdrawal of prior medications and administration of a tapering course of anti-inflammatory doses of prednisolone. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is a novel nodular clinical and eosinophilic histopathological pattern combination. This case offers evidence of a spectrum of sterile eosinophilic dermatoses rather than multiple different disease processes.

Chronic progressive lymphoedema in Friesian horses: suggestive phenotype of affected horses and genome-wide association study.

BACKGROUND: Chronic progressive lymphoedema (CPL) is a disabling condition affecting various draft horse breeds, including Friesian horses. HYPOTHESIS: The high incidence of CPL in Friesian horses suggests a genetic component and a predisposing phenotype. ANIMALS: For the genomic study, 26 affected and 19 control horses were evaluated. Body measurements were taken from 28 affected and nine control Friesian horses. METHODS AND MATERIALS: Axiom® Equine Genotyping Array with a total of 307,474 single nucleotide polymorphism (SNPs) was used for the case/control genome-wide association study (GWAS). Height, weight and leg measurements (seven different body measurements) were obtained and compared between groups. RESULTS: No significant associations were identified with the GWAS. There were significant differences (P < 0.05) in gaskin length measurements between CPL-affected horses and controls. CONCLUSION: The current study suggests that the potential genetic contribution to CPL in Friesian horses is complex and may include other SNP-associated factors. Significantly increased gaskin length of affected horses suggests a phenotype prone to developing CPL.

Examination of Fluconazole-Induced Alopecia in an Animal Model and Human Cohort.

Fluconazole-induced alopecia is a significant problem for patients receiving long-term therapy. We evaluated the hair cycle changes of fluconazole in a rat model and investigated potential molecular mechanisms. Plasma and tissue levels of retinoic acid were not found to be causal. Human patients with alopecia attributed to fluconazole also underwent detailed assessment and in both our murine model and human cohort fluconazole induced telogen effluvium. Future work further examining the mechanism of fluconazole-induced alopecia should be undertaken.

Solar-induced dorsal skin necrosis in sheep.

BACKGROUND: Solar-induced thermal burns of dark skin over the dorsum have been reported in dogs, sheep and a pig. OBJECTIVES: This report describes an outbreak of solar-induced thermal burns over the dorsal skin of criollo and Texel sheep in Uruguay. ANIMALS AND METHODS: Cross-bred criollo and pure-bred Texel adult ewes from a flock of 80 animals presented with severe skin lesions. Eight animals were evaluated clinically and skin biopsy specimens were collected from three ewes for histopathology. Epidemiological data were collected. RESULTS: Black/brown criollo sheep presented with extensive, wide, linear dorsal skin necrosis extending from the interscapular to the lumbosacral area. Necrotic skin was firm, dry and largely detached from the underlying subcutis. Nonpigmented Texel sheep showed milder lesions with rapid re-epithelialization and healing. Histological features were consistent with third-degree burns, characterized by full-thickness coagulative necrosis of epidermis and dermis, including blood vessels and adnexa. The cumulative incidence of the disease was 21% during the 30 days post-shearing, affecting 50% of criollo and 7.4% of Texel sheep (P < 0.001). CONCLUSIONS: The findings are consistent with post-shearing, sun-induced thermal burns leading to dorsal skin necrosis. Risk factors include sunlight exposure during hot months after shearing, dark skin and obesity.