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Following the successful creation of a biobank from two adult Thoroughbred mares, this study aimed to recapitulate sample collection in two adult Thoroughbred stallions as part of the Functional Annotation of the Animal Genome (FAANG) initiative. Both stallions underwent thorough physical, lameness, neurologic, and ophthalmic (including electroretinography) examinations prior to humane euthanasia. Epididymal sperm was recovered from both stallions immediately postmortem and cryopreserved. Aseptically collected full thickness skin biopsies were used to isolate, culture and cryopreserve dermal fibroblasts. Serum, plasma, cerebrospinal fluid, urine, and gastrointestinal content from various locations were collected and cryopreserved. Under guidance of a board-certified veterinary anatomic pathologist, 102 representative tissue samples were collected from both horses. Whole tissue samples were flash-frozen and prioritized tissues had nuclei isolated and cryopreserved. Spatially contemporaneous samples of each tissue were submitted for histologic examination. Antemortem and gross pathologic examination revealed mild abnormalities in both stallions. One stallion (ECA_UCD_AH3) had unilateral thoracic limb lameness and bilateral chorioretinal scars. The second stallion (ECA_UCD_AH4) had subtle symmetrical pelvic limb ataxia, symmetrical prostatomegally, and moderate gastrointestinal nematodiasis. DNA from each was whole-genome sequenced and genotyped using the GGP Equine 70K SNP array. The genomic resources and banked biological samples from these animals augments the existing resource available to the equine genomics community. Importantly we may now improve the resolution of tissue-specific gene regulation as affected by sex, as well as add sex-specific tissues and gametes.

The Functional Annotation of Animal Genomes (FAANG) project aims to identify genomic regulatory elements in both sexes across multiple stages of development in domesticated animals. This study represents the first stage of the FAANG project for the horse, Equus caballus. A biobank of 80 tissue samples, two cell lines and six body fluids was created from two adult Thoroughbred mares. Ante-mortem assessments included full physical examinations, lameness, ophthalmologic and neurologic evaluations. Complete blood counts and serum biochemistries were also performed. At necropsy, in addition to tissue samples, aliquots of serum, ethylenediaminetetraacetic acid (EDTA) plasma, heparinized plasma, cerebrospinal fluid, synovial fluid, urine and microbiome samples from all regions of the gastrointestinal and urogenital tracts were collected. Epidermal keratinocytes and dermal fibroblasts were cultured from skin samples. All tissues were grossly and histologically evaluated by a board-certified veterinary pathologist. The results of the clinical and pathological evaluations identified subclinical eosinophilic and lymphocytic infiltration throughout the length of the gastrointestinal tract as well as a mild clinical lameness in both animals. Each sample was cryo-preserved in multiple ways, and nuclei were extracted from selected tissues. These samples represent the first published systemically healthy equine-specific biobank with extensive clinical phenotyping ante- and post-mortem. The tissues in the biobank are intended for community-wide use in the functional annotation of the equine genome. The use of the biobank will improve the quality of the reference annotation and allow all equine researchers to elucidate unknown genomic and epigenomic causes of disease.

A dog with gastrointestinal signs and a history of administration of multiple drugs developed acute multifocal to coalescing ulcerative nodules and a large plaque.To describe abnormal nodular clinical lesions with an unexpected superficial and deep severe eosinophilic perivascular to interstitial inflammation.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.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.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.Un chien avec signes gastro-intestinaux et des commémoratifs d'utilisation de plusieurs traitements a développé des nodules ulcératifs multifocaux à coalescents aigus et une large plaque.Décrire les lésions cliniques nodulaires anormales avec une inflammation éosinophilique perivasculaire à interstitielle profonde sévère.Un Labrador retriever femelle stérilisée de 7 ans. MATÉRIEL ET MÉTHODE: Des tests sanguins, analyse urinaire et fécale, et des radiographies abdominales ont été réalisés; des échantillons cutanés ont été prélevés pour cytologie, culture et histopathologie. RÉSULTATS: Les tests sanguins, analyse urinaire et fécale et les radiographies ne montraient pas d'anomalie. Les cytologies ont montré des cellules inflammatoires et les cultures étaient négatives. L'examen histopathologique a révélé un œdème sous cutané et dermique, un dépôt de mucine et une inflammation périvasculaire à interstitielle par des éosinophiles avec occasionnellement de très petits agrégats denses d’éosinophiles centrés sur des amas de collagène, une exocytose d’éosinophiles et des petites pustules éosinophiles. Un exsudat de fibrine sous épidermique focal et une hémorragie résultaient en un détachement épidermique et une ulcération. La résolution clinique des signes gastro-intestinaux et dermatologiques a été observée avec l'arrêt des traitements antérieurs et l'administration de prednisolone à dose dégressive anti-inflammatoire.A la connaissance des auteurs, ceci est un nouveau patron histopathologique éosinophilique et clinique nodulaire. Ce cas prouve l'existence d'un spectre de dermatoses éosinophiliques stériles plutôt que des mécanismes pathologiques multiples différents.INTRODUCCIÓN: un perro con signos gastrointestinales y antecedentes de administración de múltiples fármacos desarrolló nódulos ulcerativos agudos multifocales a coalescentes y una placa grande. OBJETIVO: describir lesiones clínicas nodulares anormales con inesperada inflamación perivascular a intersticial eosinofílica severa superficial y profunda. ANIMAL: una perra labrador retriever esterilizada de 7 años. MÉTODOS Y MATERIALES: se realizaron análisis de sangre, análisis fecal y de orina y radiografías abdominales; se tomaron muestras de biopsia de piel para análisis citológico, cultivo y evaluación histopatológica. RESULTADOS: los análisis de sangre, las heces, el análisis de orina y las radiografías estuvieron dentro de los límites normales. Los resultados citológicos revelaron células inflamatorias y los cultivos no tuvieron crecimiento. La evaluación histopatológica mostró edema dérmico y subcutáneo, depósito de mucina e inflamación perivascular a intersticial predominantemente con eosinófilos y con ocasionales agregados densos intralesionales muy pequeños de eosinófilos alrededor de haces de colágeno, exocitosis eosinofílica y pequeñas pústulas eosinofílicas. La exudación de fibrina subepidérmica focal y hemorragia produjeron desprendimiento y ulceración epidérmica. La resolución clínica de los signos dermatológicos y gastrointestinales se observó con la retirada de medicamentos previos y la administración de un curso gradual de dosis antiinflamatorias de prednisolona. CONCLUSIONES E IMPORTANCIA CLÍNICA: a entender de los autores, esta es una combinación de patrones nodulares clínicos e inflamación predominantemente eosinófilica histopatológica. Este caso ofrece evidencia de un espectro de dermatosis eosinofílicas estériles en lugar de múltiples enfermedades diferentes.Ein Hund mit gastrointestinalen Zeichen und einer Anamnese der Verabreichung von multiplen Medikamenten entwickelte akut multifokale bis koaleszierende ulzerative Knoten und große Plaques. ZIEL: Die Beschreibung von abnormalen knotigen klinischen Läsionen mit einer unerwarteten oberflächlichen und tiefen hochgradigen eosinophilen perivaskulären bis interstitiellen Entzündung. TIER: Eine 7 Jahre alte kastrierte Labrador Retriever Hündin.Es wurden Bluttests, Kot- und Urinanalysen, und abdominale Röntgenbilder gemacht; Hautbiopsieproben wurden zur zytologischen, kulturellen und histopathologischen Analyse genommen.Die Bluttests, Kot- und Urinproben und die Röntgenbilder waren im Rahmen des Normalbereichs. Die zytologischen Ergebnisse zeigten Entzündungszellen und die Bakterienkultur ergab kein Wachstum. Die histopathologische Evaluierung zeigte ein dermales und subkutanes Ödem, Muzinablagerungen und eine perivaskuläre bis interstitielle Entzündung, die hauptsächlich aus Eosinophilen mit gelegentlichen sehr kleinen intraläsionalen dichten Aggregaten von Eosinophilen, die auf die Kollagenbündel konzentriert waren, sowie eosinophiler Exozytose und kleinen eosinophilen Pusteln bestand. Eine fokale subepidermale Fibrinexudation und Blutung resultierte in einer Abhebung der Epidermis und führte zur Ulzerierung. Nach dem Absetzen der früheren Medikamente und der Verabreichung einer ausschleichenden entzündungshemmenden Dosis von Prednisolon kam es zur klinischen Abheilung der dermatologischen und gastrointestinalen Zeichen.Nach bestem Wissen der Autoren handelt es sich hierbei um eine neuartige Kombination eines knotigen klinischen und eosinophilen histopathologischen Musters. Dieser Fall erbringt Evidenz für ein Spektrum an sterilen eosinophilen. Dermatosen anstatt für multiple verschiedene Krankheitsprozesse.背景: 消化器症状を有し複数の投薬歴のある犬が、急性に多巣性から癒合性潰瘍状結節および大型局面を発症した。 目的: 本研究の目的は、予期せぬ表層および深層性重度好酸球性血管周囲炎もしくは間質性炎症を伴う異常な結節性臨床病変を説明することであった。 被験動物: 7歳、避妊雌のラブラドール・レトリバー。 材料と方法: 血液、糞便および尿検査、腹部レントゲン撮影を実施した。皮膚生検サンプルを細胞学的、培養および組織病理学的解析のため採取した。 結果: 血液、糞便、尿検査およびレントゲン像は正常範囲内であった。細胞学的検査結果では炎症細胞を認め、培養検査では何も検出されなかった。病理組織学的評価では、真皮および皮下組織の浮腫、ムチン沈着およびコラーゲン束を中心とした好酸球による非常に小さな病巣内密集体を伴う好酸球主体の血管周囲炎から間質性炎、好酸球性エクソサイトーシスおよび好酸球性小膿疱を認めた。限局性表皮下フィブリン滲出および出血は、表皮剥離および潰瘍形成をもたらした。以前の薬物療法の中止および抗炎症用量プレドニゾロンの漸減コースの投薬により皮膚および消化器症状の臨床的解決を認めた。 結論と臨床的重要性: 著者の知る限りでは、本報告は新しい臨床的および好酸球性の組織病理学的パターンの組み合わせを有する結節病変である。本症例においては、複数の異なる疾患プロセスではなく、無菌性好酸球性皮膚炎のスペクトルのエビデンスを提供している。.背景: 有胃肠道症状和多种药物用药史的犬,出现急性多灶性至聚结溃疡性结节和大斑块。 目的: 描述异常结节性临床病变,其具有意料之外的浅表和深层重度嗜酸性血管周围至间质炎症。 动物: 一只7岁绝育雌性拉布拉多猎犬。 方法和材料: 进行血液检查、粪便和尿液分析以及腹部x线检查;采集皮肤活检样本进行细胞学、培养和组织病理学分析。 结果: 血液检查、粪便、尿液分析和x线片均在正常范围内。细胞学结果显示炎症细胞,培养基无微生物生长。组织病理学评价显示真皮和皮下水肿、粘蛋白沉积和血管周围至间质炎症,主要是嗜酸性粒细胞,偶见以胶原束为中心的非常小的病灶内嗜酸性粒细胞致密聚集,以及嗜酸性粒细胞外涉和嗜酸性小脓疱。局灶性表皮下纤维蛋白渗出和出血导致表皮脱离和溃疡。在停用既往药物,并逐渐减少泼尼松龙抗炎剂量后,观察到皮肤和胃肠道症状消退。 结论和临床重要性: 据作者所知,这是一种新型结节性症状和嗜酸性组织病理学模式组合。该病例提供了一连串无菌性嗜酸性皮肤病的证据,而不是多种不同发病过程。.Um cão com sinais gastrointestinais e histórico de administração de vários medicamentos desenvolveu nódulos ulcerativos multifocais a coalescentes agudos e uma grande placa.Descrever lesões clínicas nodulares anormais apresentando grave inflamação eosinofílica superficial e profunda perivascular a intersticial.Uma fêmea de Labrador retriever castrada de sete anos de idade. MÉTODOS E MATERIAIS: Foram realizados exames de sangue, urinálise e exame de fezes e radiografias abdominais; amostras de biópsia de pele foram coletadas para análises citológicas, culturais e histopatológicas.Os exames de sangue, fezes, urinálise e radiografias estavam dentro dos limites da normalidade. Os resultados citológicos revelaram células inflamatórias e as culturas não apresentaram crescimento. A avaliação histopatológica revelou edema dérmico e subcutâneo, deposição de mucina e inflamação perivascular a intersticial predominada por eosinófilos com agregados densos intralesionais ocasionais muito pequenos de eosinófilos centrados em feixes de colágeno, exocitose eosinofílica e pequenas pústulas eosinofílicas. Exsudação focal subepidérmica de fibrina e hemorragia resultaram em descolamento e ulceração epidérmica. A resolução clínica dos sinais dermatológicos e gastrointestinais foi observada com a retirada de medicamentos anteriores e a administração de um curso de redução gradual de doses anti-inflamatórias de prednisolona. CONCLUSÕES E IMPORTÂNCIA CLÍNICA: De acordo com o conhecimento dos autores, esta é uma nova combinação de padrões histopatológicos clínicos e eosinofílicos nodulares. Este caso fornece evidências de um espectro de dermatoses eosinofílicas estéreis, ao invés de múltiplos processos de doença diferentes.

Reports of dermal sclerosis in dogs include scleroderma or morphea of unknown cause, cicatricial alopecia and congenital/hereditary fibrosis.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.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.Les descriptions de sclérose dermique chez le chien comprennent la sclérodermie ou morphée de cause inconnue, l'alopécie cicatricielle et la fibrose congénitale/héréditaire. RÉSUMÉ CLINIQUE: Un chien chihuahua croisé mâle de 12 ans a été examiné pour lésions cutanées évoluant depuis une durée inconnue. Le chien présentait une alopécie sévère, un épaississement cutané et une lymphadénopathie périphérique. La cytologie ganglionnaire, l'immunohistochimie et les tests de clonalité ont montré un lymphome à cellule B, intermédiaire à large. La peau épaissie avait un dépôt sévère de collagène effaçant les structures annexielles. Le lymphome du chien a été traité mais les lésions cutanées sont restées identiques. Le chien a été euthanasié.A la connaissance des auteurs, ceci est la première description de lymphome B multicentrique chez un chien avec une sclérose cutanée diffuse concomitante semblable à une réaction paranéoplasique humaine.INTRODUCCIÓN: los informes de esclerosis dérmica en perros incluyen escleroderma o morfea de causa desconocida, alopecia cicatricial y fibrosis congénita/hereditaria. RESUMEN CLÍNICO: se presentó para examen de lesiones cutáneas de duración incierta un perro castrado mestizo de Chihuahua de 12 años. El perro tenía alopecia severa, engrosamiento de la piel y marcada linfadenopatía periférica. La investigación citológica de los ganglios linfáticos, la iinmunohistoquímica y las pruebas de clonalidad demostraron la presencia de un linfoma de células B medianas a grandes. La piel engrosada presentaba deposición intensa de colágeno, obliterando las folículos y estructuras anejas. El linfoma del perro fue tratado, pero las lesiones cutáneas permanecieron sin cambios. El perro fue sacrificado. CONCLUSIONES E IMPORTANCIA CLÍNICA: a entender de los autores, este es el primer informe de linfoma multicéntrico de células B en un perro junto con esclerosis cutánea difusa, similar a una reacción paraneoplásica humana.Berichte über eine dermale Sklerose bei Hunden beinhalten die Beschreibung einer Sklerodermie oder Morphea unbekannter Ursache, zikatrische Alopezie und eine kongenitale/hereditäre Fibrose.Die Hautveränderungen eines 12 Jahre alten kastrierten Chihuahuamischlingsrüden von unbekannter Dauer wurden evaluiert. Der Hund zeigte eine ausgeprägte Alopezie, Hautverdickung und eine deutliche periphere Lymphadenopathie. Die zytologische Untersuchung der Lymphknoten, eine immunhistochemische Untersuchung und ein Klonalitätstest zeigten ein intermediär- bis großzelliges B-Zell Lymphom. Die verdickte Haut zeigte eine deutliche Kollagenablagerung, die die adnexalen Strukturen auslöschten. Das Lymphom des Hundes wurde behandelt, aber die Hautveränderungen blieben gleich. Der Hund wurde euthanasiert.Nach bestem Wissen der Autoren handelt es sich hierbei um den ersten Bericht eines multizentrischen B-Zell Lymphoms bei einem Hund mit begleitender diffuser kutaner Sklerose, ähnlich einer paraneoplastischen Reaktion beim Menschen.背景: 犬の皮膚硬化症の報告には、強皮症または原因不明の形態、瘢痕性脱毛症および先天性/遺伝性線維症が含まれている。 臨床概要: 12歳、雄の去勢チワワミックス犬における、発症期間が不明な皮膚病変を評価した。 犬は重度の脱毛症、皮膚肥厚、顕著な末梢リンパ節腫脹を有していた。 リンパ節の細胞学的調査、免疫組織化学的調査およびクローナリティ検査は、中型から大型のB細胞性リンパ腫を示した。 肥厚した皮膚には、重度のコラーゲン沈着があり、付属器構造が消失していた。 犬のリンパ腫を治療したが、皮膚病変は変化しなかった。 犬は安楽死された。 結論と臨床的重要性: 著者の知る限り、これは、ヒト腫瘍随伴反応に類似した、犬の多中心型B細胞性リンパ腫に同時に認めたびまん性皮膚硬化症の最初の報告である。.背景: 关于犬皮肤硬化的报告包括不明原因的硬皮病或硬斑病,瘢痕性脱毛和先天性/遗传性纤维化。 临床总结: 对一只12岁去势雄性吉娃娃杂种犬的皮肤病变进行评估。该犬严重脱毛、皮肤增厚和明显的外周淋巴结病。淋巴结细胞学检查、免疫组化检查和克隆性检测,均显示中到大B细胞淋巴瘤。增厚的皮肤发生严重的胶原沉积,毛囊附件结构退化。这只犬的淋巴瘤得到了治疗,但皮肤病变没有改变。犬被安乐死。 结论和临床重要性: 据作者所知,这是被报告的第一例多中心型B细胞淋巴瘤患犬,同时并发弥漫性皮肤硬化,与人的副肿瘤反应类似。.Os achados clínicos de relatos de esclerose dérmica em cães incluem esclerodermia ou morfeia de causa desconhecida, alopecia cicatricial e fibrose congênita/hereditária. ACHADOS CLÍNICOS: Um cão macho castrado de 12 anos, mestiço de chihuahua foi avaliado devido a lesões cutâneas de duração desconhecida. O animal apresentava alopecia intensa, espessamento cutâneo e linfadenopatia periférica importante. A citologia de linfonodos, imunohistoquímica e teste de clonalidade revelaram um linfoma de células B intermediário a avançado. A pele espessada apresentava deposição de colágeno grave e estruturas anexas apagadas. O linfoma foi tratado, mas as lesões cutâneas permaneceram inalteradas. O cão foi eutanasiado. CONCLUSÕES E IMPORTÂNCIA CLÍNICA: De acordo com os conhecimentos do autor, este é o primeiro relato de linfoma multicêntrico de células B em um cão associado à esclerodermia difusa concomitante, similar a uma reação paraneoplásica em humanos.

OBJECTIVES To describe a small subset of canine solitary cutaneous histiocytoma in which lymph node metastasis has been documented. METHODS Cases of dogs with solitary cutaneous histiocytoma lesions and regional lymph node metastasis diagnosed via histopathology were found through a retrospective search of the databases of IDEXX Laboratories and the University of California, Davis Veterinary Medical Teaching Hospital Clinical Diagnostic Laboratories. Information on signalment, history and clinical follow-up was obtained from the submittal form and/or via a questionnaire to the submitting veterinarian. Slides were available for review in seven cases and when possible immunohistochemistry was reviewed or performed by a single pathologist. RESULTS Eight cases met the inclusion criteria. The neoplasms had the typical appearance of histiocytomas. All tested samples were immunoreactive for CD18 and lacked immunoreactivity for other lymphocyte markers and CD11d. Immunoreactivity for E-cadherin varied among the neoplasms tested. Outcome was known for five dogs and at the time of manuscript preparation three of those dogs were alive 1682 days, 570 days and 318 days post-diagnosis. Of the other two dogs with known outcome, one was euthanased shortly after diagnosis and another was hit by a car. Of the dogs that were eventually lost to follow-up, one was reported to be disease-free 1003 days after diagnosis. CLINICAL SIGNIFICANCE Metastatic histiocytoma is rarely reported and distinction from aggressive disease processes such as histiocytic sarcoma may be difficult. Based upon a small number of cases with known outcomes, some dogs with solitary metastatic histiocytoma may experience favourable outcomes.

Metastatic dissemination of carcinomas to lymph nodes impacts prognosis and treatment recommendations in human and veterinary medicine. Routine histopathologic evaluation of regional lymph nodes involves haematoxylin and eosin (HE however, identification of small volume metastases (micrometastases and individual tumour cells) may be missed without the aid of immunohistochemistry or additional step-sections. The aim of this study was to identify occult carcinoma metastases in previously diagnosed non-metastatic lymph nodes using step-sections and pancytokeratin (panCK) immunohistochemistry. Samples from 20 regional lymph nodes diagnosed as non-metastatic were serially sectioned and evaluated with panCK. Of these, 25% (n = 5) contained micrometastases (n = 1) or isolated tumour cells (n = 4). This study demonstrates the increased efficacy of serial step-sections combined with panCK immunohistochemistry to identify small volume metastases in regional lymph nodes. The prognostic significance of micrometastases and isolated tumour cells in regional lymph nodes warrants further investigation in veterinary medicine.

Feline primary cutaneous lymphomas (FPCLs) account for 0.2% to 3% of all lymphomas in cats and are more frequently dermal nonepitheliotropic small T-cell tumors. Emergence of FPCL seems unrelated to feline leukemia virus (FeLV) serological positivity or to skin inflammation. A total of 17 cutaneous lymphomas with a history of vaccine injection at the site of tumor development were selected from 47 FPCLs. Clinical presentation, histology, immunophenotype, FeLV p27 and gp70 expression, and clonality were assessed. A majority of male (12/17), domestic short-haired (13/17) cats with a mean age of 11.3 years was reported. Postinjection time of development ranged from 15 days to approximately 9 years in 5 cats. At diagnosis, 11 of 17 cats had no evidence of internal disease. Lymphomas developed in interscapular (8/17), thoracic (8/17), and flank (1/17) cutaneous regions; lacked epitheliotropism; and were characterized by necrosis (16/17), angiocentricity (13/17), angioinvasion (9/17), angiodestruction (8/17), and peripheral inflammation composed of lymphoid aggregates (14/17). FeLV gp70 and/or p27 proteins were expressed in 10 of 17 tumors. By means of World Health Organization classification, immunophenotype, and clonality, the lesions were categorized as large B-cell lymphoma (11/17), anaplastic large T-cell lymphoma (3/17), natural killer cell–like (1/17) lymphoma, or peripheral T-cell lymphoma (1/17). Lineage remained uncertain in 1 case. Cutaneous lymphomas at injection sites (CLIS) shared some clinical and pathological features with feline injection site sarcomas and with lymphomas developing in the setting of subacute to chronic inflammation reported in human beings. Persistent inflammation induced by the injection and by reactivation of FeLV expression may have contributed to emergence of CLIS.

A 14-year-old female spayed Dachshund was presented with generalized scaling, erythema, pruritus, poor quality of hair coat, and progressive weight loss. Cutaneous epitheliotropic T-cell lymphoma (CETCL) was suspected. Skin biopsies were suggestive of CETCL. However, immunohistochemistry revealed the presence of numerous CD20+ and CD3+ cells. Clonality assay demonstrated a clonal T-cell receptor gamma rearrangement and a polyclonal IgH gene rearrangement. Double-label immunofluorescence confirmed coexpression of CD3 and CD20 by neoplastic cells. By double immunohistochemistry, neoplastic cells were CD3+ and PAX5–. The results are compatible with a CD3+, CD20+ CETCL. Coexpression of CD20 and CD3 has been recognized in peripheral T-cell lymphomas. Although documented in human CETCL, it has not been reported in canine CETCL. The pathogenetic basis of CD20 expression in mycosis fungoides is explored.

Equus caballus papillomavirus 2 (EcPV2) has been proposed as an etiologic agent for genital squamous cell carcinoma (SCC), the most common malignant tumor of the horse penis. EcPV2 is commonly detected by polymerase chain reaction (PCR) on normal horse genitalia; therefore, unraveling the virus’ role in oncogenic transformation requires other methods of detection. In this study, a highly sensitive multiple-probe chromogenic in situ hybridization (ISH) technique was designed to recognize the E6/E7 oncogenes of EcPV2. ISH demonstrated abundant virus within 6 of 13 penile and preputial SCCs, whereas evidence of solar damage was found in 6 cases that were negative for EcPV2 by ISH. The ISH technique is valuable for studies of pathogenesis, since it demonstrates for the first time that the vast majority of neoplastic cells contain virus. Moreover, hybridization was present in all metastases examined, implying stability of E6/E7 expression in these clonal populations of neoplastic cells. This study contributes to the accumulating evidence for a causal role of EcPV2 in a subset of genital SCCs in horses.

Background Follicular tumors and cysts are common skin lesions in dogs. Both are distinguished based on their cellular origin (matrical, isthmus, or infundibular cells) and the type of keratin they produce. Typically, differentiation requires histopathology, as all these lesions often have similar cytologic features. Objectives The goal of this retrospective study was to identify unique cytologic features that may assist differentiation of canine benign follicular tumors and cysts at cytology, using histopathology as gold standard. Methods Electronic medical records of the University of California-Davis Veterinary Medical Teaching Hospital were searched for diagnoses of follicular tumors and cysts in dogs that had both histopathologic and cytologic diagnoses between January 2000 and December 2013. Cytologic specimens were reassessed in a blinded manner for the presence and type of background, cells, noncellular elements, and inflammation. Results Forty-six samples were included in the study. Follicular cysts (n = 25) and infundibular keratinizing acanthomas (n = 5) contained sheets of keratinized anucleate to nucleated squamous cells. Trichoepitheliomas (n = 8) had 2 primary cytologic presentations: those with primarily basaloid cells that appeared to be undergoing keratinization (3/8; 38%) and those with keratinizing anucleate to nucleated squamous cells (5/8; 63%). Trichoblastomas (n = 8) had pink matrix with spindle cells and contained cohesive clusters of basaloid cells. Conclusion Trichoblastomas, and to a lesser extent, trichoepitheliomas, have unique cytologic features with the potential to distinguish them from other benign follicular tumors and cysts. These results are an important first step toward improving the diagnostic specificity of cytologic examination of cutaneous follicular lesions.

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

Background Histopathology has been essential in advancing our knowledge in veterinary dermatology. However, morphological features and histological patterns cannot always reveal an aetiological diagnosis. Objectives Several ancillary techniques can assist in achieving an aetiological diagnosis. Some of these techniques have found their way into routine diagnostic dermatopathology, whereas others are still mainly used in research. This review discusses the utility, strengths, advantages/disadvantages and challenges associated with each technique. Methods Digital microscopy, immunohistochemistry, immunofluorescence, salt-split skin, Western blots, electron microscopy, PCR, in situ hybridization, tissue microarrays, next-generation sequencing, DNA microarrays and laser microdissection are discussed. Conclusions It is crucial to understand the limitations of each technique and to correlate the results both with pathological findings and the clinical presentation. As such, dermatopathology will remain the important link between benchtop science, available results from ancillary techniques and clinical veterinary dermatology.

BACKGROUND Hyperaesthetic leucotrichia (HL) rarely affects horses and causes painful lesions on the dorsum that result in leucotrichia. This may be a variant of erythema multiforme (EM), but there are no studies investigating this condition. OBJECTIVES Describe the clinical and histological features of HL and compare them to the histological features of EM. METHODS A retrospective review of medical records from 1985 to 2015 identified 15 horses with HL. Thirteen biopsies of HL and five of EM were evaluated and compared. RESULTS Arabian horses and their crosses (χ(2) (1) = 8.56, P

Three horses presented with variably painful, nonulcerated masses of the head or neck that were diagnosed as glomus tumours. Grossly, they were fleshy, pink to tan masses ranging from 0.4 to 9 cm in diameter, involving either the deep dermis and subcutis or the subcutis and underlying skeletal muscle. Microscopically, neoplastic epithelioid cells were arranged in sheets, cords and packets within lobules. The neoplastic cells frequently abutted and formed nodular bulges into large endothelium-lined vascular spaces, especially around the tumour periphery. Large nerve branches were associated with each tumour. As determined by immunohistochemistry, the neoplastic cells consistently expressed α-smooth muscle actin and vimentin, and some cells in two of the cases expressed desmin. A laminin- or collagen IV-positive basement membrane was demonstrated around individual tumour cells or small groups of cells in all three cases. Morphological features and immunohistochemistry supported the diagnosis of glomus tumour, most consistent with the solid type in humans. Applying a classification system used in humans, two of these tumours met criteria of malignancy (glomangiosarcomas). One horse was euthanized due to complications associated with recurrence and treatment-related necrosis and secondary infection.

Summary Reasons for performing study: Early diagnosis of chronic progressive lymphoedema (CPL) may result in more effective interventions and provide a basis for further investigation of whether early diagnosis could be used as a means of eliminating potential genetic influences by cessation of breeding from affected individuals. Hypothesis: Lymphoscintigraphy may be useful in draught horses to differentiate early lesions of CPL from other conditions in the pastern region. Methods: Forelimbs of 2 normal and 5 CPL-affected draught horses were evaluated with lymphoscintigraphy. Results: Lymphoscintigraphy showed clearly the presence of interstitial fluid stasis and delayed lymphatic drainage in the affected extremities of diseased animals in contrast to normal animals of these breeds. The rate of decreased clearance of a particulate radiopharmaceutical from the tissues was related positively to the severity of clinical signs. Conclusions and potential relevance: Our findings support the hypothesis that lymph stasis is probably responsible for the progressive swelling and concurrent skin lesions observed in association with CPL in draught horses. Lymphoscintigraphy should also prove useful in diagnosis of CPL in draught horses, even in the mild stages of the disease; such early diagnosis may result in more effective intervention.

Cutaneous vasculitis was identified by histopathological findings in 72 equines. The most frequent clinical findings were crusts/scales and oedema of the legs with the most common underlying disease being photo-aggravated dermatitis. Common laboratory findings were anaemia, neutrophilia, hyperglycaemia and hyperglobulinaemia. Histopathological patterns were most commonly cell-poor and lymphocytic/histiocytic. While statistically supported treatment recommendations could not be made due to the large numbers of confounding factors, trimethoprim-sulfa antibiotics, corticosteroids, and/or resolution or control of the underlying disease process were the most common treatment modalities.

Canine epitheliotropic cutaneous T-cell lymphoma (CTCL) is a spontaneous neoplasm of the skin and mucous membranes of aged dogs. The WHO classification of tumours of haematopoietic and lymphoid tissues in human beings recognizes three forms of cutaneous epitheliotropic CTCL: mycosis fungoides (MF), Sezary syndrome and pagetoid reticulosis. In this series of dogs (n = 56), there were 39 cases of MF, 16 cases of pagetoid reticulosis and a single case of Sezary syndrome. Epitheliotropic T cells in CTCL lesions expressed CD8 in 44 of 55 dogs (80%) assessed; neither CD4 nor CD8 was expressed in the remainder. This contrasts with human MF in which alphabeta T-cell receptors (TCR) and CD4 are dominantly expressed. Molecular clonality assessment of canine epitheliotropic CTCL utilizing PCR primers specific for canine TCR gamma (TCRG) was performed. Of the 45 canine cases assessed, TCRG monoclonality was detected in 36 cases (80%). TCR typing of canine epitheliotropic CTCL revealed that TCRgammadelta was expressed in 60% of cases, including all cases of canine pagetoid reticulosis assessed. Either muco-cutaneous junctions or tissues of the oral cavity were the sites of lesions in 32 dogs (57%) with epitheliotropic CTCL. Analysis of the topography of lesions revealed an association with TCR type. If epitheliotropic CTCL lesions occurred in both locations, T cells were more likely to express TCRgammadelta (gammadelta : alphabeta = 2.0). These data establish that canine skin trafficking T cells have a far wider range than previously thought; this includes tongue, gingival, buccal and palatine mucosae.

Cutaneous lymphoproliferative diseases encompass a spectrum of lesions, ranging from self-limiting, reactive infiltrates to high-grade lymphomas. In humans, cutaneous lymphocytosis (CL) refers to self-limiting or slowly progressive monomorphic lymphocytic infiltrates of mostly unknown cause. It morphologically mimics cutaneous lymphoma. CL in cats also is a slowly progressive disease. Immunophenotyping and clonality testing of feline CL support an indolent lymphoma for the majority of cases studied. This study reports CL in dogs. Erythematous, scaly and alopecic macules, patches or plaques were present in eight dogs. Breed predilection was not observed; six of eight dogs were females; and ages ranged from 5 to 14 years. Diffuse monomorphic non-epitheliotropic infiltrates of CD3(+) (eight of eight), CD45(-) (four of eight) or CD45(+/-) (four of eight) and CD45RA(-) (seven of eight) T lymphocytes were present in the superficial and mid-dermis. Further immunophenotyping of five cases revealed TCR-gammadelta(+) T cells (one of five) or TCR-alphabeta(+) (four of five) T cells. TCR-alphabeta(+) populations were either CD8(+) (two of four) or CD4(-)CD8(-) (2/4). Clonality testing found clonal (seven of eight) or pseudoclonal (one of eight) rearrangement of the TCR-gamma locus of the lesional T cells. Prednisone, prednisolone and methylprednisolone acetate were the most commonly administered drugs. The lesions remained stable for long periods up to 6 years. Five dogs were euthanized due to progression of the skin lesions (three of five), peripheral lymphadenopathy of unknown origin (one of five) or high-grade lymphoma (one of five). One dog was lost for follow-up and two dogs are still alive (17 and 9 months after diagnosis). Canine CL is best considered an initially indolent lymphoma, with slow progression and a potential for progression to high-grade lymphoma.

Sporotrichosis is an uncommon to rare cutaneous and subcutaneous mycosis of animals and humans caused by the dimorphic fungus Sporothrix schenckii. Twenty-three mammalian cases of sporotrichosis examined between 1987 and 2007 at the University of California, Davis - Veterinary Medical Teaching Hospital, were retrospectively evaluated with regard to the historical, clinical, diagnostic and treatment findings. Cats were the most common species affected (n = 14). In addition, sporotrichosis was diagnosed in four dogs, four horses and a donkey. Six of 23 cases were diagnosed with the localized cutaneous form of sporotrichosis (four cats, one dog, one horse), 10 with the cutaneous-lymphatic form (four cats, two dogs, three horses and a donkey), and seven with the disseminated form (six cats, one dog). Two of 23 cases did not have skin lesions at the time of diagnosis (one cat, one dog). The most common mode of diagnosis was demonstration of S. schenckii on histopathological evaluation of tissue. In contrast with most previously described sporotrichosis infections in cats, few to no fungal organisms were seen in histopathological samples (haematoxylin and eosin and special stains) in five of the 14 cats. Treatments received included itraconazole (12 cats, one dog), ketoconazole (three dogs), fluconazole (one cat, one donkey), sodium iodide (four horses, one cat) and potassium iodide (one cat, one horse, one donkey). The prognosis for successful treatment was good in all species. Fluconazole was successful in inducing resolution of the cutaneous lesions and controlling the infection in one cat with disseminated sporotrichosis.

An 8-year-old castrated male Golden Retriever was evaluated for decreased appetite, lethargy, and labored breathing of 1-week duration. Bilateral pulmonary infiltrates, hepatomegaly, and splenomegaly were present. Results of a CBC revealed marked leukocytosis (62,600/microL; reference interval 4000-15,500/microL) and large numbers of atypical cells (30,700/microL) with abundant cytoplasm. There was no concurrent anemia, neutropenia, or thrombocytopenia. Morphology of the atypical cells was most consistent with a histiocytic origin. Similar cells were identified in bone marrow aspirates, and were morphologically suggestive of the macrophage variant of disseminated histiocytic sarcoma. However, flow cytometry of the abnormal circulating cells revealed CD1c, CD11c, and major histocompatibility complex (MHC) Class II expression without expression of CD11d or lymphoid markers, consistent with myeloid dendritic antigen-presenting cells. At necropsy, the splenic architecture was effaced by neoplastic histiocytes that were also infiltrating lung, liver, an abdominal lymph node, myocardium, an bone marrow. Immunohistochemistry of the splenic neoplastic cells confirmed dendritic cell origin (CD1c+, CD11c+, MHC II+, no expression of CD11d and lymphoid markers). To the authors' knowledge, this is the first report of canine dendritic cell leukemia-in this instance accompanied by marked tissue infiltration.

Summary Reasons for performing study: Chronic progressive lymphoedema (CPL) is a recently recognised disease of the lymphatic system characterised by lesions in the skin of the lower legs in several draught horse breeds, including the Belgian Draught hourse. Clinical signs slowly progress and result in severe disfigurement of the limbs. Ideally, supportive treatment should be started early in the disease process. However early diagnosis and monitoring progression of CPL is still a challenge. Hypothesis: Elastin changes, characterised by morphological alterations as well as increased desmosine levels, in the skin of the distal limbs of horses affected with CPL are probably associated with a marked release of elastin degradation products, which elicit production of circulating anti-elastin antibodies (AEAbs) in the serum. An enzyme-linked immunosorbent assay (ELISA) for detection of serum AEAbs may document elastin breakdown. Methods: An ELISA technique was used to evaluate levels of AEAbs in sera of 97 affected Belgian Draught horses that were clinically healthy except for possible skin lesions, associated with CPL in their distal limbs. The horses were divided into 5 groups according to the severity of these skin lesions: normal horses (Group 1, n = 36), horses with mild lesions (Group 2, n = 43), horses with moderate lesions (Group 3, n = 8), horses with severe lesions (Group 4, n = 10) and, as a control, healthy Warmblood horses, unaffected by the disease (Group 5, n = 83). Results: Horses with clinical signs of CPL had significantly higher AEAb levels compared to clinically normal Belgian Draught horses and to healthy Warmblood horses. These levels correlated with severity of lesions. Conclusions: CPL in draught horses is associated with an increase of serum AEAbs. Potential relevance: Evaluation of serum levels of AEAbs by ELISA might be a useful diagnostic aid for CPL. Pathological degradation of elastic fibres, resulting in deficient support of the distal lymphatics, is proposed as a contributing factor for CPL in Belgian Draught horses.

A Quarter horse filly bred from two horses affected with HERDA (hereditary equine regional dermal asthenia) was observed clinically and its skin histologically for the 1.5 years of its life. Severe signs of the disease did not manifest until 1.5 years of age, and were not temporally related to saddling. Histological comparison to an age-, breed- and sex-matched control did not show any consistent diagnostic features. Monitoring of the proband substantiated previous reports of (i) the autosomal recessive nature of the disease, (ii) mares affected with HERDA being able to foal without damage to the skin or reproductive tract, (iii) HERDA foals appearing phenotypically normal throughout the first year of life, and (iv) demonstrated that histological interpretation of skin specimens from grossly normal skin may be insufficient to differentiate HERDA-affected horses from controls.

Chondro-osseous respiratory epithelial adenomatoid hamartomas (COREAHs) are rare tumors in the nasal cavity of people, which have not been described in other species. COREAHs in people are minimally invasive and rarely recur following excision. Histologically, these tumors are composed of disorganized, mature, nasal turbinate tissue that is organized into polypoid growths. These growths are lined by respiratory epithelium, contain glandular elements, and are organized around central cores of chondro-osseous matrix. This report describes 3 cases of dogs with nasal tumors that have histomorphology similar to that of COREAH in people. The tumors were all identified within the nasal cavity and were associated with regional bony lysis of the turbinates and surrounding skull bones, a feature that has not been reported in COREAH in people. There was no evidence of metastasis or extension beyond the nasal cavity in any of the 3 cases.

Background Canine sterile nodular panniculitis (SNP) is an inflammatory disease of the panniculus that is typically managed with immunomodulatory or immunosuppressive treatments. It has been reported to be a cutaneous marker of an underlying systemic disease. Hypothesis/Objectives To assess the presence or absence of concurrent systemic diseases associated with canine SNP and to document breed predispositions. Animals Thirty nine dogs presented to a veterinary teaching hospital from 1990 to 2012 which met inclusion criteria. Methods Inclusion in this retrospective study required a diagnosis of SNP via histopathological analysis and negative special stains for infectious organisms. Breed distributions of affected dogs were compared to all other dogs examined at this hospital during the study period. Correlations between the histological pattern of panniculitis and the histological presence of dermatitis, clinical presentation of lesions, dog breed and therapeutic outcomes were assessed. Results Australian shepherd dogs, Brittany spaniels, Dalmatians, Pomeranians and Chihuahuas were significantly over-represented, but correlations between inflammatory patterns of panniculitis and other histological and clinical factors were not identified. Based on the information available in medical records, 32 dogs (82.1%) had no concurrent systemic diseases identified. Four dogs had concurrent polyarthritis, which may be related to SNP through unknown mechanisms. Conclusions/Clinical Importance This study identified several novel breed predilections for SNP; it failed to find any clear correlations with associated systemic diseases other than polyarthritis. The histological inflammatory pattern of SNP does not predict therapeutic outcome.

To compare detection rates of feline herpesvirus 1 (FHV-1) DNA in skin biopsy specimens from cats with herpetic dermatitis, cats with nonherpetic dermatitis, and cats without dermatitis.Prevalence survey. Animals-5 cats (9 biopsy specimens) with herpetic ulcerative dermatitis, 14 cats (17 biopsy specimens) with nonherpetic ulcerative dermatitis, and 8 cats (21 biopsy specimens) without clinically apparent skin lesions.A single-phase PCR assay was used to detect FHV-1 DNA in biopsy specimens. Assay results were compared with results of histologic examination.FHV-1 DNA was detected in all 9 biopsy specimens from the 5 cats with herpetic dermatitis and in 1 of 17 biopsy specimens from the 14 cats with nonherpetic dermatitis, but was not detected in any of the 21 biopsy specimens from the 8 cats without dermatitis. When results of histologic examination were used as the gold standard, sensitivity and specificity of the PCR assay were 100% and 95%, respectively.Results confirmed that FHV-1 DNA can be detected in the skin of cats with herpetic dermatitis and suggest that the virus may play a causative role in the disease. In addition, the PCR assay may be useful in confirming a diagnosis of herpetic dermatitis.

Histiocytic proliferative diseases include reactive and neoplastic proliferations of dendritic cells (DC) or macrophages. Various forms of DC proliferations have been documented in humans and dogs; their etiology is largely unknown. With the exception of a few case reports, histiocytic proliferations have not been characterized in cats. This study summarizes clinical, morphologic, and immunophenotypic features of a feline progressive histiocytosis (FPH) in 30 cats. There was no breed or age predilection. Females were more often affected than males. Solitary or multiple nonpruritic firm papules, nodules, and plaques had a predilection for feet, legs, and face. Lesions consisted of poorly circumscribed epitheliotropic (13/30) and nonepitheliotropic (17/30) histiocytic infiltrates of the superficial and deep dermis, with variable extension into the subcutis. The histiocytic population was relatively monomorphous early in the clinical course. With disease progression, cellular pleomorphism was more frequently encountered. Histiocytes expressed CD1a, CD1c, CD18, and major histocompatibility complex class II molecules. This immunophenotype suggests a DC origin of these lesions. Coexpression of E-cadherin, a feature of cutaneous Langerhans cells, was only observed in 3 cats. FPH followed a progressive clinical course; the lesions, however, were limited to the skin for an extended period of time. Terminal involvement of internal organs was documented in 7 cases. Treatment with chemotherapeutics or immunosuppressive and immunomodulatory drugs was not successful. The etiology of FPH remains unknown. FPH is best considered an initially indolent cutaneous neoplasm, which is mostly slowly progressive and may spread beyond the skin in the terminal stage.

Nine horses from ages 5 to 21 years were diagnosed with cutaneous equine sarcoidosis (ES) over an 18-year period. In addition to skin, the lungs were frequently involved, with other organ systems affected less commonly. A predisposition for thoroughbreds and geldings was noted. Cutaneous lesions and signs included crusts, scales, alopecia and pruritus. These were found at various sites, particularly the legs/thighs/elbows, thorax, neck, face and ventral abdomen. Three horses were euthanized shortly after hospitalization; others survived as long as 12 years. Histopathologic stains, immunohistochemistry and polymerase chain reaction assays on paraffin-embedded cutaneous specimens from eight horses for Mycobacterium spp., Coccidioides immitis, Cryptococcus neoformans, Corynebacterium pseudotuberculosis, and Borrelia burgdorferi were all negative. The aetiology of ES is unlikely microbial and continues to be a diagnosis of exclusion. ES, when limited to the skin, is associated with a good prognosis, with either partial or complete response to glucocorticoid therapy in all the surviving horses.

Data on fifty horses with hereditary equine regional dermal asthenia (HERDA; "hyperelastosis cutis") were collected on clinical, histopathological, ultrastructural and immunohistological findings. All horses were Quarter horses or of Quarter horse ancestry. Pedigree evaluation strongly supported an autosomal recessive mode of inheritance. The most common lesions were seromas/haematomas, open wounds, sloughing skin, and loose, easily tented skin that did not return to its initial position. Definitive diagnosis could not be made via histopathology, although the presence of tightly grouped thin and shortened collagen fibres arranged in clusters in the deep dermis was suggestive of the disease. Trichrome, acid orcein-Giemsa and immunohistochemical stains for collagens I and III showed no consistent abnormalities compared to control horses; an increase in elastic fibres was not a consistent finding. Electron microscopy showed no abnormalities in the periodicity of the collagen bundles; neither orientation nor variation of cross-section diameter of the collagen fibrils differentiated control from affected horses. The diagnosis of HERDA relies on clinical presentation, but may be supported by suggestive (although not pathognomonic) histopathological lesions.

Clinical, morphological and immunohistochemical features of cutaneous lymphocytosis, an uncommon disease histologically resembling well-differentiated malignant lymphoma, were characterized in 23 cats. Clinical outcome was correlated with histomorphology and immunophenotype in an attempt to predict benign vs. malignant behaviour. The disease mainly affected older cats. Lesions were solitary in 61% of cats and often characterized by alopecia (73.9%), as well as erythema, scaling and ulceration. The lateral thorax was most commonly affected (43.5%). Pruritus was frequent (65.2%). Systemic signs included anorexia and weight loss. Morphologically, lesions were characterized by dermal infiltrations of well-differentiated CD3+ T-cells (100%) and aggregates of CD79+ B-cells (64.3%). Cutaneous lymphocytosis is slowly progressive and relatively benign, although in some cats systemic signs led to euthanasia. Four of 12 euthanized cats and one live cat also had lymphoid infiltrates in internal organs. Unfortunately, we were unable to predict clinical outcome by histological and immunohistochemical evaluations of skin lesions.

A condition characterized by progressive swelling, hyperkeratosis, and fibrosis of the distal limbs has been recognized in Shire, Clydesdale, and Belgian draft horses. This chronic progressive disease starts at an early age, progresses throughout the life of the horse, and often ends in disfigurement and disability of the limbs that inevitably leads to the horse's premature death. This study was undertaken to better characterize this disease.Six affected horses were donated for diagnostic workup. A detailed clinical, radiologic, gross, and histologic description is given in this report. The lesions in the limb consisted of progressive development of thick-walled lymphatics, associated with chronic dermal edema, inflammation, fibrosis, neovascularization, and elastin degeneration. In the end stages, arteriosclerosis and fibrosed veins were also present. The clinical signs and pathologic changes in this disease closely resemble the human condition of elephantiasis nostras verrucosa, a state in which chronic lymphedema plays a pivotal pathogenic role.

Canine histiocytic proliferative disorders include a wide spectrum of diseases characterized by different biologic behaviors. The etiology and pathogenesis of these diseases are largely unknown. The clinicopathologic, morphologic and immunophenotypic characteristics of canine localized and disseminated histiocytic sarcoma were examined in 39 dogs. Rottweilers, Bernese Mountain Dogs, and retrievers were most commonly affected (79%). Localized histiocytic sarcomas (19 dogs) arose from a single site, and metastatic lesions were observed in draining lymph nodes. Predilection sites were subcutis and underlying tissues on extremities, but tumors occurred in other locations, including spleen, lung, brain, nasal cavity, and bone marrow. Disseminated histiocytic sarcomas (20 dogs), a multisystem disease previously described as malignant histiocytosis, primarily affected spleen, lungs, bone marrow, liver, and lymph nodes. Both localized and disseminated canine histiocytic sarcomas were composed of pleomorphic tumor cell populations. CD1+, CD4-, CD11c+, CD11d-, MHC II+, ICAM-1+, Thy-1± tumor cells were identified in all snap-frozen samples (31 dogs). This phenotype is characteristic for myeloid dendritic antigen-presenting cell lineage. Hence, canine localized and disseminated histiocytic sarcomas are likely myeloid dendritic cell sarcomas. Dendritic antigen-presenting cells are a heterogeneous cell population with regards to their ontogeny, phenotype, function, and localization. The exact sublineage of the proliferating dendritic antigen-presenting cells involved in canine histiocytic sarcomas remains to be determined. Phenotypic analysis of formalin-fixed tissues from eight dogs was limited by available markers. Morphologic features and the phenotype CD18+, CD3-, and CD79a- were the most useful criteria to indicate likely histiocytic origin.

Suspected Streptomyces spp infections were identified in 4 cats at UC Davis Veterinary Medical Teaching Hospital between 1982 and 2011. Three had ulcerated, dark red mycetomas involving the dermis, subcutis, and fascia with fistulous tracts and/or regional lymphadenopathy. One cat had pyogranulomatous mesenteric lymphadenitis. Granulomatous inflammation in all cats contained colonies of Gram-positive, non-acid-fast organisms. All 4 cats failed to respond to aggressive medical and surgical treatment and were euthanized. Laser capture microdissection (LCM) was used to selectively harvest DNA from the affected formalin-fixed, paraffin-embedded (FFPE) tissues. Cloned amplicons from LCM-derived tissue confirmed the presence of Streptomyces spp in the dermatitis cases. Amplicons from the remaining cat with peritoneal involvement aligned with the 16S ribosomal RNA gene for Actinomycetales. Usually considered a contaminant, Streptomyces spp can be associated with refractory pyogranulomatous dermatitis and cellulitis in cats with outdoor access. LCM is useful in the diagnosis of bacterial diseases where contamination may be an issue.

Three horses were presented with a history of having developed raised cutaneous nodules, within 24-48 hours, in areas of previous injections using standard silicone-coated hypodermic needles. Skin biopsies were taken from a selected cutaneous nodule from all horses for histopathologic evaluation. Histologically, the nodules were consistent with a diagnosis of equine eosinophilic granuloma. A hypersensitivity reaction to the silicone, or another component of the coating formulation, was hypothesized to be responsible for these lesions. Two horses were experimentally injected using both coated and noncoated stainless steel hypodermic needles and skin biopsies were obtained 14 days after injection. The sites of the coated needle injections were characterized by severe eosinophilic granulomatous inflammation with and without collagenolysis. The eosinophilic granulomas with and without collagenolysis observed in these horses are proposed to represent a complex immunologic response to the silicone-based coating of most hypodermic needles.

Background Calcinosis cutis is well recognized in dogs with endogenous hyperglucocorticism and iatrogenic hyperglucocorticism, but the pathogenesis is still unclear. Objectives The objectives of the study were to identify possible correlations between histopathological patterns of dermal mineralization in skin biopsies and underlying causes for calcinosis cutis in dogs, as well as to determine breed predilection and age of onset for dogs within a hospital population. In addition, mineral analysis was performed on four biopsy samples. Animals Forty-six dogs with histopathologically confirmed calcinosis cutis were evaluated. Methods Medical records and histological sections of dogs with calcinosis cutis diagnosed by histopathology over a 21 year period were reviewed. Infrared spectrometry was used to identify the mineral in the paraffin blocks. Exact chi-squared test was used to identify breed predispositions, while a Mann–Whitney U-test was used to identify age correlations. Results Labrador retrievers, Rottweilers, boxers and Staffordshire terriers were the breeds most commonly affected in this study. Most dogs had either an exogenous or an endogenous source of corticosteroids, with the exception of five dogs with renal insufficiency. In the majority of cases, mineralization was found throughout the entire dermis. The average age of onset of calcinosis cutis for dogs with endogenous hyperglucocorticism was older than that of dogs with iatrogenic hyperglucocorticism. Using infrared spectrometry, apatite crystals were found to be the source of mineral. Conclusions and clinical importance There was no observable difference in the histopathological pattern of calcinosis cutis from dogs with endogenous hyperglucocorticism versus iatrogenic hyperglucocorticism. While glucocorticoid therapy appears to predispose dogs to developing calcinosis cutis, it remains unclear whether there is a specific dose or combination of factors that initiates the mineral deposition. Furthermore, the mineral deposition in dogs with calcinosis cutis was found to be apatite.

Objective To describe a case of testicular neoplasia and alopecia universalis in a dog, and successful treatment of the latter with ciclosporin. Animal Twelve-year-old intact male wirehaired fox terrier. Methods Castration, skin biopsy for histopathology, lymphocyte immunophenotyping and clonality analysis of the canine T-cell receptor gamma locus (TCRγ) rearrangement. Results The dog presented with symmetrical generalized alopecia. Testicular enlargement was noted which on castration was determined to be caused by bilateral interstitial cell tumours, Sertoli cell tumours and a unilateral seminoma. During the four months after castration the alopecia became more severe and widespread. Histopathology of the skin showed moderate, multifocal, mural folliculitis, peribulbar mucinosis and lymphocytic bulbitis, and targeting of anagen hair follicles. Immunophenotyping of the infiltrate showed a population of well-differentiated, small CD3-positive T lymphocytes, some expressing CD4 and others CD8. Molecular analysis revealed a polyclonal lymphocytic infiltrate, substantiating the diagnosis of alopecia areata rather than lymphoma. Treatment with ciclosporin (4.6 mg/kg) and ketoconazole (4.6 mg/kg) resulted in complete hair regrowth. Conclusion and clinical importance Ciclosporin treatment, in combination with ketoconazole, can be effective for treatment of alopecia universalis in the dog. Alopecia universalis may present with clinically noninflammatory, symmetrical, generalized alopecia, mimicking an endocrine alopecia, and skin biopsies are needed to confirm the diagnosis.

The skin provides an anatomic barrier and at the same time acts as a principal organ of communication between the animal and its environment. The skin displays remarkable species-dependent anatomic variations in its components, but its general functions are basically preserved throughout the different species. 1–6 The majority of the body surface in dogs and cats is covered by a variably dense haircoat, which exhibits species- and breed-dependent characteristics. It is partially or completely absent in a few feline and canine breeds, such as Devon rex cats, Chinese crested dogs, Mexican hairless dogs, and Abyssinian dogs. 6,7 The hairs provide an additional mechanical and physical barrier and are involved in thermoregulation as well. 6,8 The haircoat itself is often involved in cutaneous disorders and acts as an important mirror for internal diseases. On the other hand, it renders the skin itself less easily accessible for clinical observations. The thickness of the skin varies with species, breed, and body location and ranges from 0.5 to 5 mm in the dog 9 and from 0.4 to 2 mm in the cat. 7 The skin is thickest on the back and dorsal neck, becomes thinner toward the abdomen, and is thinnest in the inguinal and axillary regions. 7,9,10 Its thickness decreases from proximal to distal extremities as well. Histologic features of canine and feline skin in comparison with the human integument are presented according to their anatomic location: (1) epidermis, (2) basement membrane zone, (3) hair follicles, (4) sebaceous glands, (5) sweat glands, and (6) dermis.

— Multiple squamous cell carcinomas in situ were diagnosed in five aged cats. Despite clinical courses ranging from 18 to 30 months, there was no clinical or histologic evidence of breachment of the basement membrane. The condition closely resembles Bowen's disease in humans. Resume— Des epitheliomas spinocellulaires multiples in situ ont ete diagnostiques chez 5 chats. Maigre une anclennete clinique de 18 a 30 mois, il n'y avait pas de signes cliniques ou histologiques d'atteinte de la membrane basale. Cette affection resemble a la maladie de Bowen chez l'homme. Zusammenfassung— Bei funf alten Katzen wurden multiple plattenepithelkarzinome in situ diagnostiziert. Trotz der klinischen Krankheitverlaufe von 18 bis 30 Monaten konnte weder klinisch noch histologisch ein Durchbrechen der Basalmembran nachgewiesen werden. Dieses Bild ahnelt sehr dem Bowens Krankheit des Menschen. Resumen En cinco gatos se diagnosticaron carcinomas multiples de celulas escamosas in situ. A pesar del curso clinico de 18–30 meses no se observo evidencia clinica, o histologica de infiltracion a traves de la membrana basal. La condicion es muy semejante a la enfermedad de Bowen en medicina humana.

Chronic progressive lymphoedema (CPL) in horses, a disease of certain draught breeds, is associated with altered elastin metabolism. The characteristic lesions are seen in the skin of the lower (distal) limbs. This study was based on horses of susceptible breeds, with and without CPL, and on horses of a non-susceptible breed. Skin samples were obtained for examination from the neck (considered a non-affected region) and from the distal limb. The skin lesions were characterized histologically and the dermal elastic fibres were evaluated morphologically and quantitatively. In all horses the mean elastin concentrations were highest in the superficial dermis, gradually decreasing in the mid-dermis and deep dermis. As compared with horses of a non-susceptible breed, affected horses had increased amounts of dermal elastin in both the distal limb and neck, while non-affected horses of a susceptible breed had decreased amounts. The findings support an earlier hypothesis that CPL of horses is a generalized disease. Reduced efficiency of the elastic network in supporting the dermal lymphatics may explain the development of CPL. (C) 2008 Published by Elsevier Ltd.

The response to treatment with four topical preparations was evaluated in an 11-year-old Morgan horse mare with histologically confirmed quadrilateral cannon hyperkeratosis. Each limb was treated for 30 days with 0.1% tacrolimus ointment, 0.1% adapalene gel, 0.2% phytosphingosine spray or a water-based emollient. Response to treatment was evaluated both histologically and visually. A water-based emollient and 0.1% tacrolimus ointment produced encouraging clinical responses. Pre-treatment histopathology identified marked, mostly compact, hyperkeratosis and follicular hyperkeratosis, most prominent in the infundibular area. Following treatment, histopathology identified a mild reduction in follicular keratin production and stratum corneum thickness.