ULTRASONOGRAPHIC FEATURES OF INTESTINAL ENTRAPMENT IN DOGS

The clinical and ultrasonographic features of postoperative intestinal entrapment were assessed in five dogs. Four had vomiting and lethargy, and one had peracute collapse and hematochezia. Ultrasonographic findings in four of five dogs were similar, being characterized by focally hyperechoic mesentery and abdominal effusion, surrounding a single loop of amotile and dilated intestine. In some dogs, the affected intestinal loop had a thickened or corrugated wall, or alteration of wall layering. In one dog, the site of entrapment could be directly visualized. In the most severely affected dog, a large volume of echogenic peritoneal effusion was present, as well as fluid dilation of multiple intestinal loops. The ultrasonographic appearance of intestinal entrapment is similar to that of intestinal perforation or infarction by other causes.     

Paucibacillary paratuberculosis in a goat

A 5-year-old Saanen doe was presented with emaciation, good appetite, normal feces, and a dry flaky hair coat. Johne's disease was tentatively diagnosed. Gross postmortem findings were a thickened, corrugated ileum and enlarged edematous mesenteric lymph nodes. Histologically, there was extensive lymphocytic infiltration of the ileal lamina propria. Mycobacterium paratuberculosis could not be identified or cultured.     

Spontaneous lymphoma in a Japanese White rabbit

Lymphoma was observed in a 4-month-old female Japanese White rabbit. Grossly, the markedly enlarged mesenteric lymph nodes, prominent Peyer's patches of jejunum, splenomegaly, and enlargement of tracheobronchial lymph nodes, adrenal glands and ovaries were observed. Histologically, neoplastic lymphoid cells proliferated diffusely showing frequent mitotic figures and a characteristic 'starry sky' appearance. Their basophilic cytoplasm contained a few lipid droplets. The mesenteric lymph nodes, Peyer's patches of jejunum, and tracheobronchial lymph nodes were largely replaced by the tumor tissues. The stomach, small intestines, especially the jejunum, liver, spleen, ovaries, and adrenal glands were heavily infiltrated with neoplastic cells. These results suggest that the present lymphoma may have originated from the gastrointestinal lymphoid tissue.     

Identification of Equine Herpesvirus 5 in Horses with Lymphoma

Equine multinodular pulmonary fibrosis, equine herpesvirus 5 (EHV-5), and multicentric lymphoma were discovered in one patient. Review of gamma herpesvirus activity in humans revealed a propensity for lymphoproliferative disorders associated with infection. The objective was to determine the frequency of EHV-5 in lymphoma tissues and compare with the frequency found in the lymph nodes of clinically normal horses. Case control investigation of lymphoma-positive tissues and analysis via polymerase chain reaction (PCR) for EHV-5 was performed on 12 horses. Prospective collection and PCR analysis of lymph nodes (mesenteric or submandibular) for EHV-5 was performed on 21 control horses. Thirteen samples of lymphoma-positive tissues and fluid were submitted for PCR analysis for EHV-5. Of these, 67% was positive. In the control horse population, 14% was positive for EHV-5 (P = .004). Neoplastic samples positive for EHV-5 were classified as T-cell rich B-cell lymphoma (three), T-cell lymphoma (one), one was nondifferentiated, and two were not stained. Gamma herpesviruses in humans have been associated with lymphoproliferative diseases such as Kaposi sarcoma and Burkitt lymphoma. This study reveals an increased frequency of EHV-5 (gamma herpesvirus) in horses diagnosed with lymphoma compared with healthy control horses. Although the exact role this virus plays in the initiation or perpetuation of lymphoproliferative neoplasia is unknown, EHV-5 may be an etiologic agent associated with the development of some types of equine lymphoma.     

Precursor B-1 B cell lymphoma in a newborn calf.

A newborn Holstein female calf had neoplastic lesions in the skin and within the thoracic and abdominal cavities but not in the bone marrow, spleen, thymus, or most lymph nodes. Because the tumor cells were positive for CD79a (B cell marker), CD5 (B-1 cell marker) and terminal deoxynucleotidyl transferase (marker for immature lymphoid precursors), a diagnosis of precursor B-1 B cell lymphoma was made. The diagnosis was strongly supported by the fact that B-1 cells can develop in the fetus, unlike B-2 cells, which are produced after birth. The lymphoma was distinct from the typical calf form of lymphoma of B-2 cell origin, which does not express CD5 and is characterized by generalized lymphadenopathy and involvement of the bone marrow, blood and spleen.     

Scanning electron microscopy of the lesions of swine dysentery.

Thirty weanling pigs were examined by scanning electron microscopy at various time intervals after oral inoculation with crude colon contents from pigs affected with dysentery. The earliest recognizable change was a corrugated appearance of the mucosal surface of the large intestine. Large spirochetes, morphologically similar to Treponema hyodysenteriae, were first observed within the crypts of Lieberkühn where they seemed to proliferate onto the luminal surface. Then mucus, fibrin, erythrocytes, and disrupted epithelium appeared. Large spirochetes were always abundant in those lesions, but variable numbers of other mixed bacterial forms were also present. The earliest changes could be correlated with the appearance of large spirochetes in the feces and with early clinical signs, but not with a specific postinoculation time. Once bloody diarrhea was present, no consistent pattern was observed in development, location, or form of the lesions. With time, the lesions merely came to involve an increasingly greater surface area of the large intestine.     

Cytochemical staining characteristics of lymph nodes from normal and lymphoma-affected dogs

Frozen sections and imprint smears were used to evaluate the presence and pattern of cytochemical staining reactions in the B- and T-cell regions of lymph nodes from normal dogs and dogs with lymphoma. Staining procedures evaluated included peroxidase (PER), Sudan black B (SBB), naphthol AS-D chloroacetate esterase (CAE), alpha-naphthyl butyrate esterase (NBE), acid phosphatase (ACP), and leukocyte alkaline phosphatase (LAP). In normal lymph nodes, macrophages and some lymphocytes within the interfollicular (T-cell) region and medulla stained positive with ACP and NBE. Smaller numbers of macrophages also occurred sporadically within the germinal follicles. Cells positive for PER, SBB, and CAE were scattered infrequently throughout all regions of the normal lymph node, consistent with granulocytes and mast cells. The LAP stained cells were predominantly and prominently located within the mantle zone of secondary follicles and to a much lesser extent within the germinal centers, compatible with B-cell lymphocytes derived from follicular center cells. Of the 12 dogs with lymphoma, 7 cases (4 immunoblastic, 2 large noncleaved, 1 small noncleaved) stained diffusely positive with LAP, 4 cases (all lymphoblastic) had numerous focally positive lymphocytes using ACP and NBE, and 1 case (immunoblastic) did not stain positive with any of the cytochemical reactions. Cytochemical staining of canine lymph nodes with NBE, ACP, and LAP proved useful in distinguishing between B- or T-cell regions and detecting different cell types of canine lymphoma.     

Malignant Lymphoma with Severe Infiltrative Growth into Skeletal Muscles in WBN/Kob Rats

Although spontaneously occurring neoplasms have been reported repeatedly in F344, SD and Wistar rats, which are commonly used strains for routine toxicologic and carcinogenicity studies, there are only a few reports of malignant lymphoma or lymphatic leukemia except for large granular lymphocytic leukemia (LGL) in F344 rats. Malignant lymphoma (lymphosarcoma) is thought to be uncommon in F344 rats. The authors encountered malignant lymphomas of the non-LGL leukemia type with characteristic pathologic features in WBN/Kob rats. The mean age at onset of the disease in all 13 affected rats (8 males and 5 females) was about 60 weeks. Common and characteristic clinical signs were abnormal gait with hind limb paralysis. Macroscopically, the enlargement of the lymph nodes, spleen and liver was slight to moderate. Scattered multiple white-to-gray nodules encompassed the aorta and assumed a bead-like appearance near the thoracic and lumbar vertebrae. Histopathologically, neoplastic proliferative changes were predominant in the bone marrow tissue of the entire body, and many tumor cells infiltrated the spleen and several lymph nodes. The most striking histological features were constant and severe infiltration of tumor cells in the adipose tissue and skeletal muscle adjacent the thoracic and lumber vertebrae. Immunohistochemically, all tumor cells were positive for B-cell markers (PAX-5, CD79a and CD45) and negative for CD3. From the results of immunohistochemistry and morphological examination, these tumors were diagnosed as malignant B-cell lymphomas.     

Malignant B-cell lymphoma of the Harder's gland in a rabbit

A 22-month-old, female rabbit was presented with a 1-day history of acute unilateral exophthalmos. Ultrasonography and computed tomography (CT) of the orbit revealed an orbital mass. Retrobulbar lymphoma was diagnosed following fine-needle aspiration biopsy (FNAB). Thoracic radiographs were normal, and ultrasonography of the abdomen showed focal hypoechoic thickening of the bowel wall and hypoechoic enlarged lymph nodes. The rabbit was euthanized and histopathology identified the retrobulbar mass as B-cell malignant lymphoma of the Harder's gland. Mesenteric lymph nodes, caecum, and both kidneys were also affected. This is the first documented case of malignant lymphoma of the Harder's gland in a rabbit.     

B‐cell lymphoma with plasmacytoid differentiation,atypical cytoplasmic inclusions,and secondary leukemia in a dog

A 7‐year‐old male castrated Jack Russell Terrier was presented to the oncology service at the University of California–Davis Veterinary Medical Teaching Hospital for evaluation of suspected lymphoma. The dog had several enlarged lymph nodes and moderate lymphocytosis. Aspirates of an enlarged inguinal lymph node contained a bimorphic population of large immature lymphocytes and smaller cells with plasmacytoid features. Both cell types often contained a single large cytoplasmic inclusion that varied from clear to pale pink to sky blue. Cytologic changes were interpreted as most consistent with lymphoid neoplasia. Based on the predominantly mature cell morphology and some morphologic heterogeneity, the peripheral lymphocytosis was interpreted as most likely reactive in nature. However, the immunophenotype of the cells (CD20+, CD21+, CD79a+, MUM‐1+, and MHCII+) and clonality assays showed that tissue and blood lymphocytes were neoplastic B cells with clonal identity despite their different morphologic appearances. The cytoplasmic inclusions were positive with periodic acid‐Schiff and were immunoreactive for IgM and IgG. By transmission electron microscopy, inclusions consisted of aberrant rough endoplasmic reticulum; a few small Russell bodies were also noted. A final diagnosis of high‐grade B‐cell lymphoma with plasmacytoid differentiation, atypical cytoplasmic inclusions, and secondary leukemia was made. Chemotherapy was initiated, but the dog was euthanized due to severe and uncontrolled seizures 9 months after the initial diagnosis. This case extends the morphologic repertoire of canine plasmacytoid neoplasms and emphasizes their continuum with multicentric lymphoma. This case also demonstrates the need for advanced diagnostic techniques in establishing blood involvement in lymphoma in some instances.     

Laboratory findings, histopathology, and immunophenotype of lymphoma in domestic ferrets

Lymphoma is a common tumor in ferrets, but anatomic distribution, histomorphology, immunophenotype, laboratory abnormalities, and response to chemotherapy are incompletely defined. In this study, lymphoma was diagnosed by histopathology of tumor tissue in 29 ferrets ranging in age from 0.8 to 8.5 years, including 12 males and 17 females. Tumors involved the viscera of the abdominal cavity (n = 11), thoracic cavity (n = 1), or abdominal and thoracic cavities (n = 7); the skin (n = 2); or the viscera of both body cavities plus other sites (n = 8). Microscopically, all tumors had diffuse architecture. Assessment by histomorphology and immunophenotype classified tumors as peripheral T-cell lymphoma (n = 17), anaplastic large T-cell lymphoma (n = 5), anaplastic large B-cell lymphoma (n = 4), diffuse large B-cell lymphoma (n = 1), and Hodgkin-like lymphoma (n = 2). Cytologic evaluation of tumor tissue was diagnostic in 11 of 13 cases. Twenty-two of 27 ferrets had anemia, 2 had leukemia, and 5 were neutropenic. Common comorbid disorders were adrenal disease (n = 27) and insulinoma (n = 6). Tumors most frequently involved mesenteric lymph nodes, while enlargement of peripheral lymph nodes was uncommon (n = 3). Ferrets with Hodgkin-like lymphoma had massive enlargement of single lymph nodes. Mean survival of ferrets not immediately euthanized was 5.0 months (T-cell lymphoma) and 8.4 months (B-cell lymphoma). Ferrets treated with chemotherapy survived an average of 4.3 months (T-cell lymphoma, n = 9) or 8.8 months (B-cell lymphoma, n = 4). Results indicate that lymphomas in ferrets most commonly affect abdominal viscera, may be amenable to cytologic diagnosis, are frequently associated with anemia and, in some cases, may be chemosensitive, resulting in relatively long survival times.     

Endoscopic findings on alimentary lymphoma in 7 dogs

Alimentary lymphoma was evaluated endoscopically in 7 dogs and a histopathological examination was made to detect the origin of neoplastic lymphocytes in 5 dogs. A solitary mass in the rectum (1 case), irregular cobblestone appearance in the duodenum (4 cases) and a moderate irregular appearance resembling lymphocytic-plasmacytic enteritis (2 cases) were endoscopically detected. Endoscopic ultrasonography demonstrated increased thickness of the duodenal wall in 2 cases examined. Neoplastic lymphocytes of alimentary lymphoma proved to originate in T cells in all 5 cases examined by immunohistochemical analysis.     

Ultrasonography of the medial iliac lymph nodes in the dog

Sixty-one medial iliac lymph nodes of 38 different dogs (eight with adenocarcinoma of the apocrine glands of the anal sac, 13 with multicentric lymphoma, six with multicentric lymphoma but in clinical remission, and 11 control dogs) were evaluated to assess the ability of ultrasound to identify and interrogate these lymph nodes across the different groups and to differentiate these groups using different sonographic parameters. Ultrasound proved to be useful to assess canine medial iliac lymph nodes. An increase in size or number of detected lymph nodes or finding rounder or heterogeneous lymph nodes could differentiate lymph nodes of dogs of the control group from lymph nodes of dogs with lymphoma or an adenocarcinoma of the apocrine glands of the anal sac. Subcategories of malignancy could not be differentiated. More studies need to be performed, both with patients with reactive lymph nodes and also focusing on other canine superficial lymph nodes, before generalizing the results of this study to other areas or diseases.     

Development of the polymerase chain reaction assay based on the canine genome database for detection of monoclonality in B cell lymphoma

From the canine genome database and its bioinformatic analysis, we identified conserved sequences within the vast majority of 61 variable segments and 1 joining segment of the immunoglobulin heavy chain (IgH) gene, and designed optimal primers for polymerase chain reaction (PCR) amplification directed at these conserved sequences to evaluate the monoclonality of IgH in canine B cell lymphoma. Using the primers, a PCR-based assay was performed on fine-needle aspiration samples of normal, hyperplasia, and malignant lymph nodes and lymphoma cell lines. All fine-needle aspiration samples of five B cell lymphoma cases and the B cell lymphoma line GL-1 exhibited clonal amplification, whereas no amplification was observed in the samples from normal and hyperplasia lymph nodes, cases of T cell lymphoma, and the T cell lymphoma line CL-1. The primers we designed clearly distinguished malignant B lymphocytes from normal, reactive, and malignant T lymphocytes, indicating a potential utility of the primers for PCR-based routine clinical examination for canine B cell lymphoma.     

Equine Multinodular Pulmonary Fibrosis and Lymphoma in a Horse Associated with Equine Herpesvirus-5

A 9-year-old mare presented with a 2-week history of partial anorexia, multiple swellings in the area of the throatlatch, and purulent nasal discharge. On initial presentation, the horse had submandibular and retropharyngeal lymphadenopathy, mild ventral edema, and weight loss. Thoracic radiographs revealed a pulmonary interstitial pattern. Necropsy revealed enlarged lymph nodes throughout the body. The lung parenchyma contained multiple random, well-circumscribed nodules, which, on cut section, were pale, tan colored, and very firm with a distinct line of demarcation from the surrounding normal parenchyma. The subendocardium of the left ventricle, left atrium, and, multifocally, the right ventricle contained white, gritty areas of mineralization. There was marked subintimal mineralization of the aorta and pulmonary artery. Histopathology of the lymph nodes revealed effacement of the parenchyma by a neoplasm composed of large numbers of small mature lymphocytes, fewer large lymphocytes, and scattered moderate numbers of histiocytes. Immunohistochemistry tests for CD3, CD79a, and CD20, confirmed the lymphoma was T-cell-rich B-cell lymphoma. The lungs contained marked interstitial fibrosis with alveolar histiocytosis. Polymerase chain reaction test results of lymph node and lungs were positive for equine herpesvirus-5 (EHV-5), a gammaherpesvirus. Gammaherpesvirus infection has been associated with lymphoma and pulmonary fibrosis in other species. This report describes the association between EHV-5 and both pulmonary fibrosis and lymphoma.     

Clinical characteristics and outcome in dogs with small cell T‐cell intestinal lymphoma

Small cell intestinal lymphoma has not been well characterized in dogs. The objective of this study was to describe clinical characteristics and outcome in dogs with small cell intestinal lymphoma. We hypothesized that affected dogs would have prolonged survival compared with high‐grade gastrointestinal (GI) lymphoma. Pathology records were searched for dogs with histologically confirmed small cell GI lymphoma. Seventeen dogs with confirmed small cell intestinal lymphoma were identified, and clinical and outcome data were retrospectively collected. Histopathology was reviewed by a board‐certified pathologist, and tissue sections were subjected to immunophenotyping and molecular clonality assessment. All dogs had small cell, T‐cell, lymphoma confirmed within various regions of small intestine, with 1 dog also having disease in abdominal lymph nodes. All dogs had clinical signs attributable to GI disease; diarrhoea (n = 13) was most common. Ultrasonographic abnormalities were present in 8 of 13 dogs with abnormal wall layering (n = 7) and hyperechoic mucosal striations (n = 7) representing the most common findings. In total, 14 dogs received some form of treatment. The median survival time (MST) for all dogs was 279 days and the MST for the 14 dogs that received any treatment was 628 days. Dogs with anaemia and weight loss at presentation had significantly shorter survival times and dogs that received a combination of steroids and an alkylating agent had significantly longer survival times. Small cell, T‐cell, intestinal lymphoma is a distinct disease process in dogs, and those undergoing treatment may experience prolonged survival.     

Exclusion of cytoplasmic fragments in flow cytometric analysis of lymph node samples from dogs with lymphoma using membrane-permeable violet laser-excitable DNA-binding fluorescent dye (DyeCycle Violet)

Background: Cytoplasmic fragments derived from fragile neoplastic lymphocytes are common in samples of lymph nodes collected from dogs with lymphoma. These cytoplasmic fragments interfere with accurate gating of target cells and quantification protocols used for flow cytometry because of their variable size and expression of lymphoid cell surface antigens on their membranes. Objective: The aim of this study was to develop a method to efficiently exclude cytoplasmic fragments from flow cytometric analysis of canine lymph nodes in which lymphoma was present. Methods: Single‐cell suspensions of neoplastic cells were prepared from biopsy samples and fine‐needle aspirates of lymph nodes from 23 dogs with lymphoma. Suspensions were stained using a violet laser‐excitable (405 nm) membrane‐permeable DNA‐binding fluorescent dye (DyeCycle Violet [DCV]), incubated with antibodies against CD3, CD5, CD21, CD22, and CD45, and then stained with 7‐amino‐actinomycin D (7‐AAD), an argon‐excitable (488 nm) membrane‐impermeable DNA‐binding fluorescent dye. Multiparameter flow cytometry was used for analysis based on selective uptake and laser‐activated fluorescence of these dyes. Results: Cytoplasmic fragments, which were DCV‐negative and CD45‐positive, and dead cells, which were positive for 7‐AAD, were efficiently separated from neoplastic cells. Conclusion: Staining with DCV is a useful method to improve flow cytometric gating methods and quantitative analyses of lymph node samples from dogs with lymphoma.