Veterinary Pathology最新文献

Seven cutaneous mast cell tumors were identified in 6 geriatric California sea lions (Zalophus californianus). All tumors were within the dermis and grossly appeared as single, or in one case two, less than 1-cm-diameter, well-circumscribed, raised nodules. The majority (6/7) of the neoplasms occurred near mucocutaneous junctions (eyelid, lip, or anus). The mast cell tumors were composed of round cells arranged in sheets with poorly granulated cytoplasm or an absence of cytoplasmic granules in routine hematoxylin and eosin-stained sections. Cytology (n = 1) showed adequate staining of mast cell granules with Diff-Quik and Wright-Giemsa stains. Immunohistochemistry for cKIT revealed cytoplasmic to membranous immunoreactivity in all tumors. Giemsa staining for metachromatic granules was inconsistent. No local recurrence or metastasis has been observed in the 5 living individuals with follow-up periods ranging from 6 to 42 months. Given these findings, similar poorly granulated mast cell tumors in geriatric California sea lions are suspected to have biologically benign behavior.

The vacuole formation (VF) rat is an autosomal recessive myelin mutant characterized by generalized tremor, hypomyelination, and periaxonal VF of the central nervous system. We previously identified a nonsense mutation in the DOP1 leucine zipper-like protein A (Dop1a, also known as Dopey1) gene located on rat chromosome 8. In this study, we investigated the kinetics of oligodendrocyte progenitor cells (OPCs) and oligodendrocytes by assessing the expression patterns of transcription factors that are involved in oligodendrocyte development. The number of small, round oligodendrocytes lacking distinct cellular processes, immunolabeled with anti-adenomatous polyposis coli (APC, clone CC1) antibody, was increased in the spinal cords of the VF rats, suggesting a disrupted maturation of oligodendrocytes. In addition, the terminal differentiation and maturation of OPCs into myelinating mature oligodendrocytes may be impaired and compensatory myelination largely could fail in the VF rat. Our findings also demonstrated that the DOP1A protein is expressed in OPCs as well as mature oligodendrocytes. Finally, the intracellular trafficking of myelin basic protein (Mbp) mRNAs may be disrupted in oligodendrocytes of the VF rats. Our data suggested that DOP1A dysfunction causes impaired differentiation and maturation of oligodendrocyte-lineage cells, resulting in hypomyelination and an impaired compensatory myelination.

Urine irritant contact dermatitis is a clinically well-recognized but poorly documented condition in small animals. This study aims to systematically summarize the clinical and histopathological features of canine and feline urine scalding. Twelve cases, 10 dogs and 2 cats, were identified and included in a retrospective study of medical records and histology samples. All animals had histories of urinary incontinence with urinary problems (ectopic ureters, urolithiasis, urinary tract infection, sphincter mechanism incompetence, etc.) or a genital conformational issue with concurrent urine scalding. Gross lesions varied and included white papules/plaques, discrete nodules, and overt ulcers that localized to perigenital areas and/or involve the abdomen, inguinal areas, and proximal legs. The hallmark histopathological changes were locally extensive epithelial hyperplasia with marked spongiosis (intracellular edema) of the granular and spinous layers, diffuse parakeratosis, and variable degrees of erosion to ulceration with secondary bacterial infection and necrosis. This report summarizes the clinical and histopathological findings in urine scalding and highlights the importance of the clinical history, presentation, and lesion distribution to achieve the correct diagnosis. In the absence of a history or awareness by the pathologist of this unique histopathological pattern, urine scalding could easily be misdiagnosed.

In the summer of 2023 in southern Brazil, there was a fatal outbreak of acute gastrointestinal disease in calves that ingested Titya abstersa caterpillars. The outbreak affected 6 of the 40 calves raised in an extensive system, with a mortality rate of 15%. The clinical signs included anorexia, hypersalivation, ruminal bloat, fever (39.8-40.5°C), polydipsia, and gastric reflux. Death occurred within 24 to 48 hours after the onset of the clinical signs. Macroscopic and microscopic findings revealed necrotic rumenitis, reticulitis, esophagitis, and longitudinal and transverse sections of golden structures with backward-facing barbs, consistent with intralesional caterpillar setae. This study aimed to characterize the clinical, epidemiological, and pathological aspects from the necropsies of 3 affected calves. To date, there have been no similar reports regarding the ingestion of T. abstersa caterpillars.

Oral mucosal melanomas (OMMs) are the most frequent oral malignancy in dogs, often characterized by aggressive local behavior and a high metastatic rate. The mechanisms that drive canine OMM metastasis are still largely unknown, providing for limited therapeutic approaches once the disease has spread to metastatic sites. The objective of this investigation was to evaluate the differences in gene expression between canine primary OMMs and their matched nodal metastases. Transcriptional profiling of formalin-fixed, paraffin-embedded biopsies of 4 canine OMMs and their respective lymph node biopsies was performed using exon microarrays. Confirmation of the differential expression of selected genes was subsequently sought by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) on 13 paired samples (primary tumor-metastatic lymph node). Results highlight the activation of pathways associated with actin cytoskeleton organization, and cellular motility and migration. In particular, transcriptional data indicated increased expression of genes associated with Rac1 signaling-regulated cell migration, including ELMO1, VAV3, and DOCK2, in nodal metastases. Overall, the results of this investigation point to a significant role for Rac1 signaling in the pathogenesis of OMM metastasis to regional lymph nodes. The Rac1 signaling-associated genes highlighted herein are indeed involved in the activation of cellular migration, and one, or more, may represent a future therapeutic target to prevent metastatic dissemination, or treat OMM with distant metastases.

Intracytoplasmic inclusions in atrial cardiomyocytes of guinea pigs were incidentally identified on routine postmortem evaluation. This study was conducted to assess their location, incidence, morphology, staining properties, ultrastructural appearance, epidemiological characteristics, and pathologic significance. Retrospective cases from 2014 to 2022 with right and/or left atria sampled for histologic examination were selected, and hearts of guinea pigs necropsied in 2023 were systematically formalin-fixed and included. Inclusions were identified in 27 of 28 animals (96%). They were significantly more numerous in the right atrium compared with the left atrium (P < .001, Wilcoxon signed-rank test) and preferentially located as clusters in the subendocardial region. None of these inclusions were detected in the ventricular myocardium. These inclusions were intracytoplasmic, ovoid to linear, frequently fragmented, slightly basophilic to amphophilic in hemalum, eosin, and saffron-stained sections and measured from 1 to 130 µm in length. They stained positively with periodic acid-Schiff, Gomori-Grocott's methenamine silver, and Alcian blue pH 2.5; negatively or unstained with Alcian blue pH 1, toluidine blue, von Kossa, Congo red, and Masson's trichrome; and were amylase resistant. Transmission electronic microscopy revealed slightly electron-dense, non-membrane-bound aggregates of filaments interspersed with granular material compatible with polyglucosan bodies. Animals under 1-year-old had significantly fewer inclusions than older animals (P = .002, Mann-Whitney U test). Inclusion density in the right atrium was not associated with sex, body weight, local heart lesions, or cardiac or systemic disease. Those features are similar to a human condition named basophilic degeneration, reported here for the first time in guinea pigs.

Dogs with sudden acquired retinal degeneration syndrome (SARDS) have rapid onset visual dysfunction and subsequent outer retinal atrophy. The pathophysiology of SARDS is poorly understood. This study's objective was to examine the histologic features of choriocapillaris perfusion and Bruch's membrane morphology in eyes from dogs with SARDS. Archived, paraffin-embedded, sagittal eye sections of dogs with SARDS (n = 12), age/breed-matched healthy control dogs (n = 24), and age-matched dogs with progressive retinal atrophy (PRA, n = 12) were evaluated. Choriocapillaris density and patency were estimated using light microscopy and immunofluorescence to quantify patent vessels containing luminal erythrocytes and nonpatent vessels with empty lumens. The outer nuclear layer (ONL) nuclei density was quantified to determine the extent of atrophy. The thickness of Bruch's membrane was measured from transmission electron microscopy images (n = 5 SARDS, 5 PRA, 6 controls). Statistical analyses were performed using 1-way analysis of variance (ANOVA) and the Spearman rank correlation. Both SARDS and PRA samples had lower patent vessel densities compared with controls (P = .006 and .04, respectively). ONL nuclei density and choriocapillaris vessel density were associated in samples from dogs with PRA (r = 0.94-1.00, P < .05), but not SARDS (r = 0.14-0.66, P > .05). Eyes with SARDS had thicker Bruch's membrane than controls and dogs with PRA (P < .0001). Outer retinal disorders in dogs, including SARDS and PRA, are associated with alterations in choriocapillaris characteristics and Bruch's membrane thickness. Whether these findings are causative or correlative with disease is unknown.

Ulcerative dermatitis is common in captive cephalopods and often results from trauma to their delicate epidermis with subsequent infection by opportunistic pathogens. We report 3 cases of fatal ulcerative dermatitis caused by a rare pathogen in a cohort of captive, adult, north Pacific big eye octopuses (Octopus californicus). Abundant, 5 to 8 µm diameter, roughly spherical organisms, often located in pairs or clusters, were infiltrating the ulcers in all 3 cases. Ultrastructurally, the organisms possessed multilamellated to scaley cell walls and were surrounded by empty, irregularly ovoid, 1 μm diameter, membrane-bound structures consistent with an ectoplasmic net. These features are consistent with thraustochytrid, a marine saprophyte. Previous reports of pathogenic thraustochytrid infections in cephalopods are rare, suggesting this is an uncommon albeit serious infection in captive cephalopod populations.