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Melanoma is the most common malignant oral tumor in dogs. It frequently presents a diagnostic challenge as many melanomas lack or contain scant melanin and may have a variable microscopic phenotype. Previous studies evaluating immunohistochemical markers for diagnosing melanoma have shown limited sensitivity and/or specificity for S-100, PNL2, melan A, TRP-1, TRP-2, and HMB-45. Sry-related HMG-box gene 10 (SOX-10) is a transcription factor associated with melanocytic, peripheral neural crest, and peripheral nervous system development. In humans, SOX-10 expression has been demonstrated in melanoma, breast carcinoma, glioma, and schwannoma, but has only recently been explored in veterinary species. In this study, 198 tumors comprised of 147 melanocytic neoplasms and 51 non-melanocytic neoplasms were evaluated by immunohistochemistry using a tissue microarray for SOX-10, PNL2, melan A, TRP-1, and TRP-2 expressions. The SOX-10 had the highest diagnostic sensitivity (96.7%) in melanomas. In addition, SOX-10 had the highest percentage (91.5%; 130/142) of melanomas label at least 75% of neoplastic cells. Of the 51 selected non-melanocytic tumors examined, SOX-10 labeling was observed in mammary carcinomas (6/6), gliomas (4/4), and oral soft tissue sarcomas (4/18). Of the 41 non-melanocytic oral neoplasms evaluated, SOX-10 had a specificity of 92.7%. Therefore, SOX-10 represents a useful immunohistochemical screening marker for the diagnosis of canine melanoma given its extremely high sensitivity and robust labeling intensity. The SOX-10 may have utility in diagnosing some non-melanocytic neoplasms in the dog, although this requires further investigation. [ABSTRACT FROM AUTHOR]

In general, the prognosis for feline nocardiosis is guarded, although patients with localized infections may respond to appropriate therapy. Pyogranulomatous dermatitis and panniculitis in domestic small animals are associated with a broad array of infectious and noninfectious causes, making diagnosis difficult and necessitating the use of ancillary diagnostic testing.[3] Diagnosis in this case was confounded by the previous biopsy yielding no evidence of infectious etiologies despite special stains. Delays in diagnosis and treatment tend to compromise response to therapy and disease may become chronic, progressive, and refractory, and insufficient duration of therapy may lead to disease recurrence. Differential Diagnoses An infectious pododermatitis and panniculitis was considered as the primary differential diagnosis given the physical examination findings, although no infectious agents were apparent on cytology and no infectious agents were identified on the previous biopsy with Gram and Fite-Faraco acid-fast stains. [Extracted from the article]

Pulmonary capillary hemangiomatosis (PCH) and pulmonary veno-occlusive disease (PVOD) are rare causes of primary pulmonary hypertension in humans, and, in 2016, were reported in dogs. A 1-y-old, neutered male Persian cat was presented for autopsy after sudden death several hours after grooming. Grossly, the lungs were mottled red-to-pink, contained rubbery-to-firm nodular foci, and there was moderate-to-marked left-sided cardiomegaly and left atrial dilation, consistent with hypertrophic cardiomyopathy. Microscopically, there was multifocal to regionally extensive capillary proliferation within pulmonary alveolar septa and around respiratory bronchioles, with nodular aggregates of densely arranged capillaries that replaced pulmonary alveolar spaces. Rare occlusive venous remodeling was identified in Verhoeff-van Gieson-stained sections. The gross and microscopic changes were consistent with PCH with rare features of PVOD. Hypertrophic cardiomyopathy was interpreted as potentially contributing to the cause of death, but unrelated to the pulmonary vascular proliferation. [ABSTRACT FROM AUTHOR]

Genital condyloma-like lesions were observed on male and female cynomolgus macaque monkeys (Macaca fascicularis) originating from the island of Mauritius. Cytobrush and/or biopsy samples were obtained from lesions of 57 affected macaques. Primary histologic features included eosinophilic, neutrophilic, and lymphoplasmacytic penile and vulvar inflammation, epidermal hyperplasia with acanthosis, and increased collagenous stroma. Polymerase chain reaction–based assays to amplify viral DNA revealed the presence of macaque lymphocryptovirus (LCV) DNA but not papillomavirus or poxvirus DNA. Subsequent DNA analyses of 3 genomic regions of LCV identified isolates associated with lesions in 19/25 (76%) biopsies and 19/57 (33%) cytology samples. Variable immunolabeling for proteins related to the human LCV Epstein Barr Virus was observed within intralesional plasma cells, stromal cells, and epithelial cells. Further work is needed to characterize the epidemiologic features of these lesions and their association with LCV infection in Mauritian-origin macaques. [ABSTRACT FROM AUTHOR]

The development of a protocol to reproducibly induce thymic atrophy, as occurs in feline immunodeficiency virus (FIV) infection and other immunosuppressive diseases, and to consistently estimate thymic volume, provides a valuable tool in the search of innovative and novel therapeutic strategies. Magnetic resonance imaging (MRI) using the short tau inversion recovery (STIR) technique, with fat suppression properties, was determined to provide an optimized means of locating, defining, and quantitatively estimating thymus volume in young cats. Thymic atrophy was induced in four, 8–10-week-old kittens with a single, directed 500cGy dose of 6MV X-rays from a clinical linear accelerator, and sequential MR images of the cranial mediastinum were collected at 2, 7, 14, and 21 days post irradiation (PI). Irradiation induced a severe reduction in thymic volume, which was decreased, on average, to 47% that of normal, by 7 days PI. Histopathology confirmed marked, diffuse thymic atrophy, characterized by reduced thymic volume, decreased overall cellularity, increased apoptosis, histiocytosis, and reduced distinction of the corticomedullary junction, comparable to that seen in acute FIV infection. Beginning on day 7 PI, thymic volumes rebounded slightly and continued to increase over the following 14 days, regaining 3–35% of original volume. These findings demonstrate the feasibility and advantages of using this non-invasive, in vivo imaging technique to measure and evaluate changes in thymic volume in physiologic and experimental situations. All experimental protocols in this study were approved by the Institutional Animal Care and Use Committee (IACUC) at Auburn University. [Copyright &y& Elsevier]