Histamine Receptor Expression in the Gastrointestinal Tract of Dogs.

Histamine is an important mediator of many physiological processes including gastrointestinal function that acts via four different histamine receptors (H1R to H4R). Elevated histamine levels and increased HR messenger ribonucleic acid (mRNA) have been shown in humans with gastrointestinal disorders such as irritable bowel syndrome or allergic intestinal diseases. As there is limited knowledge concerning the distribution of histamine receptors (HR) in dogs, one aim of this study was to investigate the expression of histamine 1 receptor (H1R), histamine 2 receptor (H2R) and histamine 4 receptor (H4R) in the canine gastrointestinal tract at protein level using immunohistochemistry. Histamine 1 receptor, H2R and H4R were widely expressed throughout the canine gastrointestinal tract including epithelial, mesenchymal, neuronal and immune cells. In addition, in situ hybridisation was established for detecting canine H4R mRNA. Results showed H4R mRNA to be present in enterocytes, lamina propria immune cells and submucosal plexus in the duodenum and colon of nearly all investigated animals. The results elucidate the importance of HR in the canine gut and represent the basis for investigating their possible impact on canine inflammatory gastrointestinal disorders.

Skeletal muscle hypoplasia represents the only significant lesion in peripheral organs of ruminants infected with Schmallenberg virus during gestation.

Schmallenberg virus (SBV), an arbovirus within the family Bunyaviridae, represents a ruminant pathogen that has caused epidemic abortion and birth of malformed or stillborn animals in many European countries since August 2011. Histological and immunohistochemical analysis of peripheral tissues of SBV-infected animals, including lymphoid tissues, endocrine organs and tissues of the gastrointestinal, urogenital and respiratory system, were analyzed in order to elucidate the occurrence of SBV-associated changes and the presence of viral antigens and RNA. Twenty calves and 12 lambs as well as age-matched controls were included in this study. Significant muscular hypoplasia with fatty replacement was noted in affected calves and lambs. In addition, hepatocellular degeneration with lymphohistiocytic inflammation, interstitial fibrosis and biliary hyperplasia was detected in calves. All animals lacked SBV-positive cells in the peripheral organs. These observations resemble those found in Akabane virus- and Cache Valley virus-infected animals and support the occurrence of few residual lesions in peripheral organs following SBV infection.

Neurolymphomatosis in three horses with multicentric T-cell-rich B-cell lymphoma.

Neurolymphomatosis is a rare manifestation of lymphoma and is characterized by neoplastic infiltration of the peripheral nervous system. The present report describes neoplastic infiltration of peripheral nerves in three horses with multicentric lymphoma. Immunohistochemistry revealed the presence of CD79a(+) lymphoblastic cells and well-differentiated CD3(+) T cells, characteristic of T-cell-rich B-cell lymphoma in all cases. Nerve infiltration by lymphoma is rare, but should be considered as a differential diagnosis for peripheral neuropathy in horses with lymphoma.

Lack of schmallenberg virus in ruminant brain tissues archived from 1961 to 2010 in Germany.

Schmallenberg virus (SBV) is an orthobunyavirus of the family Bunyaviridae that is associated with stillbirth and malformations in ruminants. The infection has been identified in many European countries since August 2011. The present study investigated retrospectively the occurrence of SBV infection in ruminants using immunohistochemistry and in-situ hybridization in brain tissues archived between 1961 and 2010 (112 cattle, 57 sheep, 16 goats and 27 wild ruminants). Eighty-five animals with inflammatory brain lesions and 47 animals with malformations were included. Due to the lack of SBV protein and RNA detection, SBV appears to have been introduced recently into Northern parts of Europe from tropical or subtropical regions.

Vaginal canine transmissible venereal tumour associated with intra-tumoural Leishmania spp. amastigotes in an asymptomatic female dog.

A 2-year-old female boxer dog was presented with a vaginal serosanguineous discharge not associated with oestrus. There was a friable mass occupying the upper caudal part of the vagina. Cytological and histological examination revealed a monomorphic population of neoplastic round cells consistent with canine transmissible venereal tumour (TVT). In addition, Leishmania spp. amastigotes were found within the neoplastic tissue. In order to characterize whether the amastigotes were present inside macrophages and/or neoplastic cells, a co-localization study using cell- and pathogen-specific markers was performed. To detect Leishmania spp. a 5.8S ribosomal RNA (rRNA) parasite-specific sequence was used for in-situ hybridization and Mac387 was used as a macrophage marker for immunohistochemistry. Leishmania spp. rRNA was detected inside Mac387(+) macrophages and within the cytoplasm of some neoplastic cells. DNA isolation and polymerase chain reaction using specific primers and sequencing analysis identified the organism as Leishmania infantum (syn. Leishmania chagasi). This is the first report describing infection of tumour cells by L. infantum in a genital TVT from an asymptomatic bitch. Transplantation of Leishmania-laden neoplastic cells could represent an alternative route of venereal transmission of leishmaniasis among dogs.