Lymphoid neoplasms in swine.

Seventeen cases of lymphoid neoplasms in swine were investigated and divided into eight histological types. Cases 1-3 were precursor B lymphoblastic leukemias, which occurred in three piglets from the same dam. Cases 4 and 5 were diagnosed, respectively, as a precursor B lymphoblastic lymphoma and a thymic B cell lymphoma, because there were cytological differences between the lymphomas. These five cases of immature B cell malignancies expressed CD79a and terminal deoxynucleotidyl transferase (TdT). Mature B cell lymphomas were divisible into follicular (case 6), diffuse centroblastic (case 7) and intestinal large B cell (cases 8-11) lymphomas. Unlike in case 7, the neoplastic cells in cases 8-11 showed cytological features intermediate between centroblasts and immunoblasts. The mature lymphomas were characterized by positive immunolabeling for CD79a and cytoplasmic immunoglobulins. A case of thymic γδ T cell lymphoma (case 12) were positive for CD3, CD5, WC1 and TdT. Instead of TdT, perforin was expressed in γδ T cell lymphomas (cases 13-17), whose histological characteristics were epitheliotropism, homing into T cell zones of lymphatic tissues, and cytological atypia and pleomorphism. In the present study, lymphoid neoplasms could be classified into discrete histological types, some of which were considered to be specific for swine.

Relationship between bacterial translocation and isolation of enteric bacteria from extraintestinal organs in slaughtered pigs.

Enteric bacteria, especially Escherichia coli, have been isolated from porcine livers affected with ascariasis. We hypothesized that reason for this bacterial isolation was due to bacterial translocation (BT). In order to clarify the association between ascariasis and isolation of Enterobacteriaceae in the livers,12 pigs with ascariasis (ascariasis group), 12 pigs without ascariasis (non-ascariasis A group) were used. Jejunum, ileum, cecum, colon, livers, mesenteric lymph nodes (MLN), and portal blood were obtained from these pigs. Furthermore, in order to confirm the presence of BT in pigs, the samples mentioned above as well as spleens were obtained from 11 pigs without ascariasis (non-ascariasis B group) and 6 specific pathogen free (SPF) pigs without ascariasis (non-ascariasis SPF group). In the first experiment, the gram-negative bacteria were isolated from livers (66.7%), MLN (91.7%), and portal blood (55.6%) regardless the presence of ascariasis. In the second experiment, isolation rates of gram-negative and -positive bacteria were 52.9 and 66.7% for livers, 52.9 and 80% for MLN, 11.8 and 26.7% for spleens, and 40 and 20% for portal blood of the pigs examined, respectively. E. coli and Staphylococcus were the predominant isolates from these pigs. A large number of antigens immunodetected by E. coli polyclonal antibody were found in the damaged cecal mucosa. These findings present evidence that BT is generally observed in slaughtered pigs regardless the presence of ascariasis. This has challenged our notion that extraintestinal organs of pigs are usually maintained as sterile.

Aborted lesions of a pig associated with Arcanobacterium abortisuis and the immunohistochemical features.

A microorganism isolated from an aborted sow's placenta has been proposed as a novel species, Arcanobacterium abortisuis. The lesions in the placenta were suppurative and necrotic placentitis, whereas lesions of three fetuses were suppurative bronchopneumonia. Gram and Grocott-positive organisms in these lesions were immunolabeled with anti- Arcanobacterium abortisuis antibody. This is the first case report, which showed the association of Arcanobacterium abortisuis with the aborted lesions of a pig.

Granulomatous lymphadenitis associated with Actinobacillus pleuropneumoniae serotype 2 in slaughter barrows.

This study evaluated the occurrence of granulomatous lymphadenitis and its association with Actinobacillus spp. in 151 653 slaughtered pigs. Markedly enlarged pulmonary hilar, mediastinal, mandibular or hepatic lymph nodes were detected in 6 castrated males. The cut surfaces showed multifocal yellow-white lesions. Histologically, gram-negative bacilli were visible in the centers of the lesions with asteroid bodies, epithelioid cells, and multinucleated giant cells. Dense fibrous connective tissue surrounded these granulomatous lesions. Immunohistochemically, the organisms reacted with polyclonal antibodies against Actinobacillus pleuropneumoniae serotype 2 in all 6 barrows. The organism was isolated from the lymph nodes of all 6 animals. The results indicate that the granulomatous lymphadenitis was associated with A. pleuropneumoniae serotype 2 and the disorder had a tendency to occur in slaughter barrows.

Prevalence of granulomatous pleuropneumonia associated with Actinobacillus pleuropneumoniae serotype 2 in slaughter pigs.

A total of 14,818 slaughtered pigs were examined macroscopically. Of these, 25 pigs with porcine pleuropneumonia were collected and the relations among Actinobacillus spp. and granulomatous lesions in organs (lungs and tonsils) were evaluated. In the lungs, only Actinobacillus pleuropneumoniae serotype 2 was isolated from 20 of the pigs. Histologically, granulomatous pneumonia with A. pleuropneumoniae antigen was detected in 8 of the pigs. The antigen was visible in the centers of the lesions along with asteroid bodies, epithelioid cells and multinucleated giant cells. In the tonsils, granulomatous lesions were not detected, although A. pleuropneumoniae serotype 2 (5 pigs), serotype 7 (1 pig), Actinobacillus porcitonsillarum (1 pig) and Actinobacillus minor (1 pig) were isolated. The present survey suggests that multifocal granulomatous pneumonia in slaughter pigs could be highly associated with A. pleuropneumoniae serotype 2 infection.

Hemorrhagic necrotizing splenitis in a slaughter pig infected with Arcanobacterium species.

A 6-month-old barrow presented with lethargy, inappetence and dysstasia. At necropsy, multiple coalescing hemorrhagic foci were detected in the margins of the spleen. Gram-positive bacilli were isolated from the spleen, kidney, muscle and liver. Comparative 16S rDNA gene sequencing analysis of the isolates (TO16177) revealed that they would be the same species of unpublished Arcanobacterium species strain HJ57-14E (accession no. gi 18873551) (99.7% similarity based on a comparison of 675 bp). Histologic examination of the splenic tissue sections revealed extensive necrosis and inflammation, and gram-positive bacilli were discernible. Multifocal necrosis was also detected in the liver. Immunohistochemically, the isolates were cross-reacted with polyclonal antibodies against Arcanobacterium pyogenes and Actinomyces naeslundii, and the reaction was strong for the latter. Similar reactions were found in the suppurative lesions of the tonsil, and occasionally in the spleen and lymph nodes. The present results indicate that the unpublished Arcanobacterium species induced multiple organ failure accompanied by acute hemorrhagic necrotizing splenitis in this growing-finishing pig.