Differentiation between resident mature lymphocyte populations and small cell lymphoma cannot be made by cytological review alone and remains challenging in histopathological review. These cases warrant application of complementary tools like PCR-based immunoglobulin (IG) and T-cell receptor (TCR) clonality testing for confirmation. In this prospective study, diagnostic sensitivity and specificity of different primer sets for routine diagnosis of feline TCR gamma (TCRG) and complete IG heavy chain (IGH) gene rearrangements were assessed. Fine needle aspirates from 20 feline lymphoma cases and lymph node material from 10 cats without hematopoietic neoplasia were subjected to clonality testing. Feline lymphoma cell lines and previously confirmed patient material served as positive control. Detection limits for clonal populations within a polyclonal background was 90% for B-cells and 50% for T-cells. Diagnostic sensitivity and specificity of the clonality assay were 70% and 90%. Overall diagnostic accuracy was 77%, positive predictive value 93% and negative predictive value 60%.

BackgroundMany dogs suffering from inflammatory bowel disease (IBD) are presented to veterinary clinics. These patients are diagnosed based on a history of chronic gastrointestinal signs and biopsy‐confirmed histopathologic intestinal inflammation. Intestinal intraepithelial lymphocytes (IEL) are part of the first line of defense in the gastrointestinal immune system. Alterations in IEL subsets may play a role in the pathogenesis of IBD.HypothesisThe aim of this study was to characterize the phenotypes of IEL in dogs with IBD compared with healthy control dogs.AnimalsIntestinal intraepithelial lymphocytes subpopulations of control dogs (n = 5) obtained from endoscopic biopsies (EB) were compared to those obtained from full thickness biopsies (FTB) on the same day. In addition, the phenotypes of IEL from FTB of control dogs (n = 10) were compared with EB of IBD dogs (n = 10). Each participant was scored clinically using the canine inflammatory bowel disease activity index (CIBDAI), and all samples were graded histopathologically. Three‐color flow cytometry of isolated IEL was performed using monoclonal antibodies against T‐ and B‐lymphocyte subpopulations.ResultsNo significant differences in the composition of IEL subpopulations were found in control dogs based on method of biopsy. The IBD dogs had significantly higher CIBDAI and histopathologic scores compared with control dogs and their IEL contained a significantly higher frequency TCRγδ T‐cells.Conclusions and Clinical ImportanceEndoscopic biopsies provide suitable samples for 3‐color flow cytometry when studying canine intestinal IEL and IBD patients show significant changes of major T‐cell subsets compared to healthy control dogs.

BackgroundInflammatory bowel disease (IBD) is common in dogs. Despite the known importance of intestinal lymphocytes in its pathogenesis, little is known about the role of peripheral blood lymphocytes (PBLs) in IBD.ObjectivesThe aims of this study were (1) comparison of PBLs analyzed by flow cytometry (FCM) in IBD dogs and healthy controls and (2) comparison of PBLs in IBD dogs at the time of diagnosis and in dogs in clinical remission.AnimalsWhole blood samples of 19 IBD dogs at the time of diagnosis and blood samples of 6 dogs in clinical remission were collected. Ten healthy dogs served as controls.MethodsIn this prospective observational study, PBLs were analyzed with multicolor FCM by staining with a panel of anticanine and cross‐reactive monoclonal antibodies against T‐ and B‐cell differentiation antigens, including CD45, CD3, CD4, CD8α, CD8β, TCRαβ, TCRγδ, CD79αcy, and CD21.ResultsThe IBD patients’ PBLs had significantly decreased percentages of TCRγδ+ T lymphocytes (median: healthy dogs, 3.32; IBD dogs, 0.97; P = 0.03) and CD21+ B cells (median: healthy dogs, 27.61; IBD dogs, 17.26; P = 0.04). There were no significant differences in PBLs between pretreatment and follow‐up samples.Conclusions and Clinical ImportanceThe differences between PBLs in healthy and IBD dogs analyzed by FCM indicate an imbalance of lymphocytes with different immunologic functions and emphasize the potential value of this technique in a larger cohort of dogs. The PBLs did not differ between IBD dogs before treatment and clinically well‐controlled dogs after treatment.

The effects of a fish-meal-and potato-protein-based diet enriched with omega-3 PUFA on intestinal inflammatory activity and expression of genes active in fatty acid (FA) uptake were tested in the duodenum of dogs with food responsive diarrhea (FRD; n ¼ 14) and inflammatory bowel disease (IBD; n ¼ 7). The clinical outcome was estimated by monitoring the canine IBD activity index (CIBDAI) before and after treatment. Dogs were treated with the diet alone (FRD) or the diet in combination with immunosuppressants (IBD). The duodenal mRNA levels of FA translocase, FA transport protein-1,-3,-4,-6, long chain acyl coenzyme synthetase-1,-4,-5,-6, liver-and intestinal-FA binding proteins, interleukin-1b (IL)-1b and -6, and tumor necrosis factor-a were measured by quantitative PCR. The CIBDAI significantly decreased after treatment in all dogs. The mRNA levels of target genes were associated both with disease phenotype and dietary treatment. Significantly different expression patterns were found for IL-1b, FA translocase, intestinal-FA binding protein, FA transport proteins-1,-3,-6, and long chain acyl coenzyme synthetase-5,-6. In conclusion, the mRNA levels of some of the genes involved in duodenal FA uptake may be altered by a fish-meal-and potato-protein-based diet enriched with omega-3 PUFA. This may be beneficial for the treatment of canine chronic enteropathies, particularly FRD.Practical applications: In this study, feeding dogs on a fish-meal-and potato-protein-based diet enriched with omega-3 PUFA resulted in marked suppression of intestinal inflammatory activity, mainly in the duodenum of dogs with food responsive diarrhea with a concomitant alteration of some of the genes involved in FA uptake. In IBD, however, a combination of diet and immunosuppressive drugs was required. The present study provides preliminary insights into the importance of the herein tested dietary composition for the treatment of canine chronic enteropathies, revealing that an omega-3 PUFA-enriched diet can be beneficial to the animal's health and wellbeing. Furthermore, our results serve as the basis for future investigations using different food ingredients and FA compositions to identify the optimal dietary mixture that could be equally effective for dietary prophylactic or therapeutic treatment of canine chronic enteropathies, or both.Keywords: Canine inflammatory bowel disease index activity / Fatty acid transporters / Intestinal bowel disease / Omega-6 and omega-3 fatty acids

Background: In inflammatory bowel disease (IBD) in humans, phosphorylated signal transducer and activator of transcription 3 (pSTAT3) is upregulated in mucosal epithelial cells and correlates with clinical severity.Hypothesis/Objective: To investigate the expression pattern of pSTAT3 in the mucosa of dogs with chronic inflammatory enteropathy (CIE) and explore correlations between its expression and clinical and histopathological severity scoring.Animals: Twenty-eight canine CIE patients grouped into food-responsive enteropathy (FRE; 9), steroid-responsive enteropathy (SRE; 10), and protein-losing enteropathy (PLE; 9). Ten healthy beagle dogs served as controls (CO).Methods: Retrospective case control study. Immunohistochemistry was used to detect pSTAT3 in canine duodenal mucosa samples.Results: Compared to CO, SRE (P < .001) and PLE (P < .001) dogs had significantly higher pSTAT3 expression in the villus epithelium. The SRE group had a significantly higher expression in the villus lamina propria (VLP) compared to controls (P = .009). In the crypt epithelium (CE), all CIE dogs had significantly higher pSTAT3 expression (FRE, P = .002; SRE, P = .003; PLE, P < .001) compared to CO. In the lamina propria crypt region (CLP), dogs with FRE (P = .04) and SRE (P = .03) had significantly upregulated pSTAT3 compared to controls. A positive correlation was found between canine chronic enteropathy clinical activity index (CCECAI) scoring and pSTAT3 expression for both epithelial (rho = .541; P < .001) and crypt regions (rho = .32; P = .02).Conclusions and Clinical Importance: pSTAT3 is upregulated in CIE in dogs, correlates with clinical severity, and may be helpful as a clinical marker in dogs with CIE.