Veterinary Pathology

  • In Memoriam: Asa Harris Mosher, VMD, PhD, Diplomate ACVP, 1936-2014 5 novembre 2015
    Keenan, C. M.
  • Vitamin C Depletion in Prenatal Guinea Pigs as a Model of Lissencephaly Type II 5 novembre 2015
    Capo, I., Hinic, N., Lalosevic, D., Vuckovic, N., Stilinovic, N., Markovic, J., Sekulic, S.
    Humans and guinea pigs are unable to produce vitamin C, with deficiency resulting in a well-known disorder of collagen synthesis. Pial basement membrane structure preservation is essential in the proper migration of neurons. In our study, intrauterine deprivation of vitamin C in guinea pig fetuses led to a collagen synthesis disorder, weakness, and finally a breach of pial basement membrane. We found excessive migration of the external germinal layer cells into the subarachnoid space of the cerebellum through defects in the pial basement membrane. The changes ranged from focal rupture of pial basement membranes to their complete disintegration. The loss of proper folia formation resulted in macroscopically visible flattening of the cerebellar surface. Different grades of dysplastic changes in the folia of the cerebellar cortex were observed in 2 experimental groups assigned different limits to mark the time of commencement and duration of vitamin C deprivation. The most severe form of dysplastic changes was characterized by marked irregularity of the cerebellar cortex similar to that in lissencephaly type II. Thus, prenatal vitamin C deficiency represents a novel animal model to study the effects of collagen synthesis on development of breaches in the pial basement membrane, disordered migration of neurons, dysplasia of cerebellar cortex, and the pathogenesis of lissencephaly.
  • Reviewers Summary 5 novembre 2015
  • Orchitis and Epididymitis in Koalas (Phascolarctos cinereus) Infected With Chlamydia pecorum 5 novembre 2015
    Johnston, S. D., Deif, H. H., McKinnon, A., Theilemann, P., Griffith, J. E., Higgins, D. P.
    Although Chlamydia causes disease of the urethra and prostate of male koalas, its impact on the testis and epididymis has not been examined. This study describes chronic-active and granulomatous orchitis and epididymitis with interstitial fibrosis associated with infection by Chlamydia pecorum in 2 of 18 adult male koalas being euthanized at a koala hospital, 8 of which also had chlamydial prostatitis. By immunohistochemistry and transmission electron microscopy, chlamydial inclusions were demonstrated within Sertoli cells directly associated with mild inflammation surrounding intact seminiferous and epididymal tubules, marked pyogranulomatous inflammation around disrupted tubules, replacement of tubules by interstitial fibrosis, and aspermia. The presence of C. pecorum but not Chlamydia pneumoniae was detected by quantitative polymerase chain reaction of formalin-fixed tissues of the left and right testes and right epididymis in 1 animal. This is the first report of orchitis and epididymitis in a koala infected with C. pecorum.
  • Aleutian Disease: An Emerging Disease in Free-Ranging Striped Skunks (Mephitis mephitis) From California 5 novembre 2015
    LaDouceur, E. E. B., Anderson, M., Ritchie, B. W., Ciembor, P., Rimoldi, G., Piazza, M., Pesti, D., Clifford, D. L., Giannitti, F.
    Aleutian disease virus (ADV, Amdovirus, Parvoviridae) primarily infects farmed mustelids (mink and ferrets) but also other fur-bearing animals and humans. Three Aleutian disease (AD) cases have been described in captive striped skunks; however, little is known about the relevance of AD in free-ranging carnivores. This work describes the pathological findings and temporospatial distribution in 7 cases of AD in free-ranging striped skunks. All cases showed neurologic disease and were found in a 46-month period (2010–2013) within a localized geographical region in California. Lesions included multisystemic plasmacytic and lymphocytic inflammation (ie, interstitial nephritis, myocarditis, hepatitis, meningoencephalitis, pneumonia, and splenitis), glomerulonephritis, arteritis with or without fibrinoid necrosis in several organs (ie, kidney, heart, brain, and spleen), splenomegaly, ascites/hydrothorax, and/or encephalomalacia with cerebral microangiopathy. ADV infection was confirmed in all cases by specific polymerase chain reaction and/or in situ hybridization. The results suggest that AD is an emerging disease in free-ranging striped skunks in California.
  • Specific Cleavage of the Nucleoprotein of Fish Rhabdovirus 5 novembre 2015
    Zhou, G.- Z., Yi, Y.- J., Chen, Z.- Y., Zhang, Q.- Y.
    Siniperca chuatsi rhabdovirus (SCRV) is one of myriad rhabdoviruses recorded in fish. Preliminary data show that inhibition of the SCRV nucleoprotein (N) could significantly reduce the progeny virus titers in infected Epithelioma papulosum cyprinid (EPC) cells. Here, the authors propose that cleavage of the viral 47-kDa N protein is caspase-mediated based on caspase inhibition experiments, transient expression in EPC transfection, and analysis of cleavage sites. Cleavage of the SCRV N protein in culture was prevented by a pan-caspase inhibitor, z-VAD-FMK (z-Val-Ala-DL-Asp-fluoromethyl ketone). Subsequently, N was transiently expressed in EPC cells, the results of which indicated that the specific cleavage of N also occurred in the cells transfected with N-GFP plasmid. Several truncated fragments of the N gene were constructed and transiently transfected into EPC cells. Immunoblotting results indicated that D324 and D374 are the cleavage sites of N by caspases. The authors also found that z-VAD-FMK could inhibit the cytopathic effect in SCRV-infected EPC cells but not affect the production of infectious progeny, suggesting that the caspase-mediated cleavage of N protein is not required for in vitro SCRV replication. To the authors’ knowledge, this is the first report on the cleavage of rhabdovirus proteins.
  • Pododermatitis in Captive and Free-Ranging Greater Flamingos (Phoenicopterus roseus) 5 novembre 2015
    Wyss, F., Schumacher, V., Wenker, C., Hoby, S., Gobeli, S., Arnaud, A., Engels, M., Friess, M., Lange, C. E., Stoffel, M. H., Robert, N.
    Pododermatitis is frequent in captive flamingos worldwide, but little is known about the associated histopathologic lesions. Involvement of a papillomavirus or herpesvirus has been suspected. Histopathologic evaluation and viral assessment of biopsies from 19 live and 10 dead captive greater flamingos were performed. Selected samples were further examined by transmission electron microscopy and immunohistochemistry. Feet from 10 dead free-ranging greater flamingos were also evaluated. The histologic appearance of lesions of flamingos of increasing age was interpreted as the progression of pododermatitis. Mild histologic lesions were seen in a 3-week-old flamingo chick with no macroscopic lesions, and these were characterized by Micrococcus-like bacteria in the stratum corneum associated with exocytosis of heterophils. The inflammation associated with these bacteria may lead to further histologic changes: irregular columnar proliferations, papillary squirting, and dyskeratosis. In more chronic lesions, hydropic degeneration of keratinocytes, epidermal hyperplasia, and dyskeratosis were seen at the epidermis, as well as proliferation of new blood vessels and increased intercellular matrix in the dermis. Papillomavirus DNA was not identified in any of the samples, while herpesvirus DNA was seen only in a few cases; therefore, these viruses were not thought to be the cause of the lesions. Poor skin health through suboptimal husbandry may weaken the epidermal barrier and predispose the skin to invasion of Micrococcus-like bacteria. Histologic lesions were identified in very young flamingos with no macroscopic lesions; this is likely to be an early stage lesion that may progress to macroscopic lesions.
  • Characterization of Spontaneous Mammary Tumors in Domestic Djungarian Hamsters (Phodopus sungorus) 5 novembre 2015
    Yoshimura, H., Kimura-Tsukada, N., Ono, Y., Michishita, M., Ohkusu-Tsukada, K., Matsuda, Y., Ishiwata, T., Takahashi, K.
    Mammary tumors that spontaneously occurred in domestic Djungarian hamsters (Phodopus sungorus) were histologically examined. Forty-five mammary tumors included 14 adenomas, 18 adenocarcinomas, 1 lipid-rich carcinoma, 2 adenoacanthomas, 2 malignant adenomyoepitheliomas, 1 benign mixed tumor, and 7 "balloon cell" carcinosarcomas. The latter 4 types were newly recognized neoplasms in Djungarian hamsters. The relatively high incidence of spontaneous mammary carcinosarcomas in domestic Djungarian hamsters is intriguing. Carcinosarcomas exhibited anomalous histological features made up of a mixture of glandular cells, polygonal cells (including "balloon cells"), and sarcomatous spindle cells in varying proportions. Transitional features from glandular cells to polygonal cells and subsequently to sarcomatous spindle cells were observed. Using immunohistochemistry, we observed that glandular cells exhibited an epithelial phenotype (cytokeratin(+)/vimentin(–)), spindle cells exhibited a mesenchymal phenotype (cytokeratin(–)/vimentin(+)), and polygonal cells exhibited an intermediate phenotype (cytokeratin(+)/vimentin(+)). Reduction or loss of β-catenin expression and gain of S100A4 expression were observed in polygonal and spindle cells. The polygonal cell population included a varying number of characteristic cells that were expanded by large intracytoplasmic vacuoles. Electron microscopy revealed that these "balloon cells" had large cytoplasmic lumens lined by microvilli. These observations suggest that epithelial-mesenchymal transition may account for the pathogenesis of mammary carcinosarcomas in Djungarian hamsters.
  • Beyond Parasitism: Hepatic Lesions in Stranded Harbor Porpoises (Phocoena phocoena) Without Trematode (Campula oblonga) Infections 5 novembre 2015
    Hiemstra, S., Harkema, L., Wiersma, L. C. M., Keesler, R. I.
    The liver can be an indicator of the health of an individual or of a group, which can be especially important to identify agents that can cause disease in multiple species. To better characterize hepatic lesions in stranded harbor porpoises (Phocoena phocoena), we analyzed the livers from 39 porpoises that stranded along the Dutch coast between December 2008 and December 2012. The animals were selected because they had either gross or histologic liver lesions with minimal autolysis and no evidence of trematode (Campula oblonga) infection. The most common finding was a chronic hepatitis (22/39, 56.4%) that was often associated with significant disease reported in another organ system (18/22, 81.8%), of which 14 had chronic systemic disease. One case of chronic hepatitis was so severe as to mimic lymphoma, which could only be differentiated with immunohistochemistry. The other common lesions were lipidosis (11/39, 28.2%) and acute hepatitis (6/39, 15.4%), often in combination with mild chronic changes. Overall, although there were no consistent trends in etiology for the hepatic lesions, lipidosis was associated with starvation (8/11, 72.7%) and acute disease, and acute hepatitis was associated with bacterial infections and sepsis (6/6, 100%).
  • Respiratory Pathology and Pathogens in Wild Urban Rats (Rattus norvegicus and Rattus rattus) 5 novembre 2015
    Rothenburger, J. L., Himsworth, C. G., Clifford, C. B., Ellis, J., Treuting, P. M., Leighton, F. A.
    Norway (Rattus norvegicus) and black rats (Rattus rattus) are common peridomestic species, yet little is known about wild rat ecology, including their natural diseases. We describe gross and histological lesions in the respiratory tract of a sample of 711 wild urban rats. A subset was examined for 19 distinct categories of histological lesions in the respiratory tract. Testing for known respiratory pathogens included serology and polymerase chain reaction (PCR) of lung samples. Grossly evident lesions were rare (8/711; 1%). Upper respiratory tract inflammation was present in 93 of 107 (87%) rats and included rhinitis, submucosal and periglandular lymphoplasmacytic tracheitis, and/or tracheal intraluminal necrotic debris and was significantly associated (P < .05) with the presence of cilia-associated respiratory bacillus (CARB), Mycoplasma pulmonis, and increased body mass (odds ratio [OR] = 1.09; 95% confidence interval [CI] = 1.05–1.14 per 10 g). Within the lungs, peribronchiolar and/or perivascular lymphoplasmacytic cuffs were present in 152 of 199 rats (76%) and were also significantly associated (P ≤ .02) with CARB, M. pulmonis, and increased body mass (OR = 1.20; 95% CI = 1.14–1.27 per 10 g). Rats were frequently coinfected with M. pulmonis and CARB, and lesions associated with these pathogens were histologically indistinguishable. Pneumocystis sp was detected in 48 of 102 (47%) rats using PCR but was not significantly associated with lesions. This description of pathology in the respiratory system of wild rats demonstrates that respiratory disease is common. Although the impact of these lesions on individual and population health remains to be investigated, respiratory disease may be an important contributor to wild rat morbidity and mortality.