ACVIM consensus statement guidelines on diagnosing and distinguishing low-grade neoplastic from inflammatory lymphocytic chronic enteropathies in cats

Intestinal Ultrasonographic Measurements in Cats Diagnosed with Lymphoplasmacytic Enteritis and Low-Grade T-Cell Lymphoma Based on Either Histology/Immunohistochemistry or Clonality Testing-And Assessment of the Effects of Therapy on Wall Layering After 3 and 6 Months of Treatment

It is unknown whether intestinal ultrasonographic measurements differ between lymphoplasmacytic enteritis (LPE) and low-grade intestinal T-cell lymphoma (LGITL) in cats if the diagnosis is based either on histology/immunohistochemistry (IHC) or on clonality assay results. The effects of treatment on intestinal ultrasonographic measurements are also unknown. Therefore, we prospectively compared small intestinal wall layering between cats with LPE and LGITL and investigated whether there were differences between the groups when the diagnostic gold standard was either histology/IHC or clonality testing. We evaluated the effects of standardized treatment in a subset of cats. The thicknesses of the total wall, mucosa, muscularis, and submucosa were measured in the duodenum, jejunum, and ileum, and ratios (muscularis to submucosa, muscularis to total wall thickness) were calculated. The thickness of the largest mesenteric lymph nodes was also determined. Ultrasonographic measurements from duodenal and jejunal segments were grouped together, and ileal segments were assessed separately. Sixteen cats with standardized full-thickness biopsies from the stomach, duodenum, jejunum, and ileum were included. Samples for clonality testing were fresh-frozen and analyzed later, and the standardized treatment was based on histologic/IHC diagnoses. Ultrasonographic measurements were compared between LPE and LGITL when diagnoses were either based on histology/IHC or clonality testing using a linear mixed model. Repeated ultrasonographic measurements of segments were available for seven cats after 12 weeks (five LPE, two LGITL) and five cats after 24 weeks (three LPE, two LGITL) of standardized treatment. We found that none of the ultrasonographic measurements differed between LPE and LGITL regardless of the diagnostic gold standard used. During treatment, only the ratio of lamina muscularis thickness to total wall thickness decreased significantly in LPE cats after 12 and 24 weeks compared to baseline. In conclusion, the herein evaluated ultrasonographic variables did not differ between LPE and LGITL and the diagnostic gold standard used had no influence on the results. The detected change over time during treatment in LPE cats requires further study.

Effect of Iron Deficiency on Short-Term Response to Treatment in Cats With Chronic Enteropathies

BACKGROUND

Iron deficiency in humans with chronic inflammatory enteropathies (CIE) is associated with active disease and anemia-related morbidity.

OBJECTIVES

To compare iron deficiency prevalence in cats with CIE versus low-grade alimentary lymphoma (LGAL) and secondarily, determine the effect of iron deficiency on short-term clinical response in CIE cats.

ANIMALS

Twenty-eight client-owned cats with primary gastrointestinal disease, including 14 CIE cats and 14 LGAL cats.

METHODS

Prospective study. Cats were enrolled when they presented for gastrointestinal endoscopy. Iron panel (serum iron, ferritin, total iron binding capacity), CBC, cobalamin, serum amyloid A, methylmalonic acid, and clinical disease severity were evaluated. Cats were categorized as "normal" or "iron deficient" using calculated transferrin saturation. CIE cats were reevaluated 14, 30, and 90 days after initiation of non-standardized gastrointestinal disease treatment. Clinical response was compared based on iron and anemia status.

RESULTS

Iron deficiency was diagnosed in 7/28 cats (2/14 CIE, 5/14 LGAL cats) at enrollment and developed in four additional CIE cats during follow-up. While 9/28 cats were anemic at enrollment, neither anemia (relative risk [RR], 0.90; 95% confidence interval [CI], 0.13-5.50) nor iron status (RR, 0.4; 95% CI, 0.10-1.5) was associated with treatment response. Transferrin saturation was lower in LGAL cats (22%; 95% CI, 20%-27%) than in CIE cats (30%; 95% CI, 26%-39%).

CONCLUSIONS AND CLINICAL IMPORTANCE

There was high prevalence of iron deficiency over the first 90 days of treatment in CIE cats. Iron deficiency did not affect short-term response to individualized treatment of gastrointestinal disease.

Adverse events after fecal microbiota transplantation in nine cats: a case series

This case series describes nine cases of fecal microbiota transplantation in cats and associated adverse events (AEs) from two tertiary referral hospitals. AEs were graded according to criteria established by the Veterinary Cooperative Oncology Group's Common Terminology Criteria for Adverse Events (VCOG-CTCAE v2) for clinical trials. Cats received 5-6 g/kg donor feces 2-6 times for chronic enteropathy (n = 4) or therapy-resistant diarrhea (n = 5). AEs included lethargy (n = 7), vomiting (n = 5), diarrhea (n = 5), weight loss (n = 5), inappetence (n = 5), dehydration (n = 5), abdominal pain (n = 2), gastroenterocolitis based on ultrasound (n = 2) and anorexia (n = 1). Temperatures of up to 103.4°F were noted but did not meet the criteria for AEs (>103.5°F). Cats responded to antimicrobials (metronidazole, marbofloxacin), anthelmintics (fenbendazole), supportive care with fluids, ondansetron and mirtazapine (n = 5), gabapentin (n = 2), pradofloxacin (n = 1) or self-resolved (n = 1). Positive response to fecal microbiota transplantation for the presenting complaint was seen in eight cats (seven complete, one partial and transient).Relevance and novel informationFecal microbiota transplantation is increasing in usage among companion animals. Fecal microbiota transplantations in cats have been rarely described in the literature as have AEs after administration. This case series represents the first description of AEs after fecal microbiota transplantation in cats.

Concurrent mucosal and transmural feline intestinal T-cell lymphomas show differing T-cell clonality

The clonality of 14 feline intestinal small and large T-cell lymphomas were examined, which consisted of concurrent mucosal and transmural lymphomas, respectively. Histologically, the small cell lymphomas were localized to the mucosal region and were observed adjacent to large T-cell lymphoma lesions. The large T-cell lymphomas were spread throughout the submucosal region, forming transmural lesions. Both cell types were immunohistochemically stained using anti-cluster of differentiation 3 antibody. For clonality analysis, genomic DNA was extracted from formalin-fixed, paraffin-embedded sections of the mucosal and transmural lesions, separately. Clonality analysis was performed using primer sets targeting T cell receptor beta, T cell receptor delta, and T cell receptor gamma loci. In 12/14 cats, the results of the clonality analysis for T-cells differed between the mucosal and transmural lesions. Despite the fact that the cellular morphologies differed between lesion types, the T-cell clonality was consistent in 1/14 cats, suggesting a common clonal origin. In the remaining case, the clonal relationship between the 2 lesions could not be determined. These results indicate that concurrent lymphomas with small and large T-cells in their mucosal and transmural lesions, respectively, develop via separate pathogenic mechanisms.

Artificial intelligence-based quantification of lymphocytes in feline small intestinal biopsies

Feline chronic enteropathy is a poorly defined condition of older cats that encompasses chronic enteritis to low-grade intestinal lymphoma. The histological evaluation of lymphocyte numbers and distribution in small intestinal biopsies is crucial for classification and grading. However, conventional histological methods for lymphocyte quantification have low interobserver agreement, resulting in low diagnostic reliability. This study aimed to develop and validate an artificial intelligence (AI) model to detect intraepithelial and lamina propria lymphocytes in hematoxylin and eosin-stained small intestinal biopsies from cats. The median sensitivity, positive predictive value, and F1 score of the AI model compared with the majority opinion of 11 veterinary anatomic pathologists, were 100% (interquartile range [IQR] 67%-100%), 57% (IQR 38%-83%), and 67% (IQR 43%-80%) for intraepithelial lymphocytes, and 89% (IQR 71%-100%), 67% (IQR 50%-82%), and 70% (IQR 43%-80%) for lamina propria lymphocytes, respectively. Errors included false negatives in whole-slide images with faded stain and false positives in misidentifying enterocyte nuclei. Semiquantitative grading at the whole-slide level showed low interobserver agreement among pathologists, underscoring the need for a reproducible quantitative approach. While semiquantitative grade and AI-derived lymphocyte counts correlated positively, the AI-derived lymphocyte counts overlapped between different grades. Our AI model, when supervised by a pathologist, offers a reproducible, objective, and quantitative assessment of feline intestinal lymphocytes at the whole-slide level, and has the potential to enhance diagnostic accuracy and consistency for feline chronic enteropathy.

Evaluation of serum and fecal parameters in cats with low-grade intestinal T-cell lymphoma (LGITCL)

Lymphoma is the most common neoplasia in the intestine of cats. According to ACVIM consensus statement, low-grade intestinal T-cell lymphoma (LGITCL) represents a monomorphic infiltration of the lamina propria or epithelium or both of cats with small, mature, neoplastic (clonal) T lymphocytes. Despite the importance as contributing factors of inheritance and environment in the pathogenesis of LGITCL, the chronic inflammatory status plays a fundamental role. The aim of the present study was to investigate possible diagnostic and prognostic parameters in LGITCL. Selected fecal bacteria and serum biomarkers (serum amyloid A [SAA]; citrulline; total protein; amylase; lipase; DGGR lipase; cholesterol; lipopolysaccharides [LPS], and zonulin) were evaluated in 12 cats (lymphoma group - LG) with histologically diagnosed low-grade intestinal T- cell lymphoma (LGITCL) and then compared with a control group consisting of 12 clinically healthy cats (CG). The evaluation of fecal bacterial population showed the significant decrease of Faecalibacterium spp. (P = 0,045) and Clostridium hiranonis (P = 0,0433) and a significant increase in E. coli (P = 0,045), Streptococcus spp. (P = 0,0003) and Turicibacter spp. (P = 0,0056) in the lymphoma group. Serology showed a significant decrease of total proteins (P = 0,092), amylase (P = 0,092) and cholesterol (P = 0,0112) in LG group compared to controls. The present results allowed the authors to state that in cats LGITCL is possibly associated to a change in the gastrointestinal environment and to a condition of protein losing enteropathy. Further studies with a larger cohort of patients are needed to confirm the present results and to point out other possible changes.

Fecal and Serum Calprotectin Concentrations in Cats With Chronic Enteropathies Before and During Treatment

Background

Chronic enteropathies (CE) are common in cats. Reliable biomarkers that can distinguish different causes and predict or monitor responses to treatment are currently lacking.

Hypothesis/Objectives

Evaluate calprotectin concentrations in serum and feces as potential biomarkers in cats with CE.

Animals

Forty‐three cats with either chronic inflammatory enteropathy (CIE; n = 25) or small cell gastrointestinal lymphoma (SCGL; n = 18) and 36 healthy cats were prospectively enrolled.

Methods

Fecal and serum calprotectin concentrations were determined before and during treatment. Cats with CIE were treated with diet, prednisolone, or diet and prednisolone, and cats with SCGL were treated with prednisolone plus chlorambucil with or without diet.

Results

Compared to controls, fecal calprotectin concentration was significantly higher in cats with CE (median, ≤ 161 ng/g; range, ≤ 161–2827 vs. median, ≤ 161 ng/g; range, ≤ 161–790; p = 0.01). No significant differences were found in fecal (median ≤ 161 ng/g; range, ≤ 161–1920 vs. median, 189 ng/g; range, ≤ 161–2827; p = 0.3) or serum calprotectin (median, ≤ 1291 mg/L; range, ≤ 1291–15 358 vs. median, ≤ 1291 mg/L; range, ≤ 1291–6422; p = 0.99) between cats with CIE and cats with SCGL. Fecal calprotectin was significantly decreased after treatment in cats with CE (median, ≤ 161 ng/g; range, ≤ 161–1897 vs. median, ≤ 161 ng/g; range, ≤ 161–656; p = 0.02).

Conclusions

Fecal calprotectin concentration might be a good biomarker for diagnosis and treatment monitoring for a subset of cats with CE. Serum calprotectin concentrations do not seem to be useful for diagnosis or treatment monitoring in cats with CE. Neither fecal nor serum calprotectin concentrations could differentiate cats with CIE from cats with SCGL.

Classification performance and reproducibility of GPT-4 omni for information extraction from veterinary electronic health records

Large language models (LLMs) can extract information from veterinary electronic health records (EHRs), but performance differences between models, the effect of hyperparameter settings, and the influence of text ambiguity have not been previously evaluated. This study addresses these gaps by comparing the performance of GPT-4 omni (GPT-4o) and GPT-3.5 Turbo under different conditions and by investigating the relationship between human interobserver agreement and LLM errors. The LLMs and five humans were tasked with identifying six clinical signs associated with feline chronic enteropathy in 250 EHRs from a veterinary referral hospital. When compared to the majority opinion of human respondents, GPT-4o demonstrated 96.9% sensitivity [interquartile range (IQR) 92.9-99.3%], 97.6% specificity (IQR 96.5-98.5%), 80.7% positive predictive value (IQR 70.8-84.6%), 99.5% negative predictive value (IQR 99.0-99.9%), 84.4% F1 score (IQR 77.3-90.4%), and 96.3% balanced accuracy (IQR 95.0-97.9%). The performance of GPT-4o was significantly better than that of its predecessor, GPT-3.5 Turbo, particularly with respect to sensitivity where GPT-3.5 Turbo only achieved 81.7% (IQR 78.9-84.8%). GPT-4o demonstrated greater reproducibility than human pairs, with an average Cohen's kappa of 0.98 (IQR 0.98-0.99) compared to 0.80 (IQR 0.78-0.81) with humans. Most GPT-4o errors occurred in instances where humans disagreed [35/43 errors (81.4%)], suggesting that these errors were more likely caused by ambiguity of the EHR than explicit model faults. Using GPT-4o to automate information extraction from veterinary EHRs is a viable alternative to manual extraction, but requires validation for the intended setting to ensure accuracy and reliability.

Plasma glucagon-like peptide-2 in cats with chronic enteropathies

OBJECTIVES

The objective of this study was to compare plasma glucagon-like peptide-2 (GLP-2) concentrations in cats with chronic enteropathies (CE) with those of healthy cats.

METHODS

Nineteen client-owned cats with a histopathologic diagnosis of either idiopathic chronic enteropathy (CIE) or low-grade lymphoma and six healthy client-owned cats were enrolled in a prospective study between 2 December 2021 and 9 June 2023. Fasted and postprandial plasma GLP-2 concentrations were measured via ELISA in CE cats at the time gastrointestinal biopsies were obtained and before CE treatment. In cats with a histopathologic diagnosis of CIE, plasma GLP-2 concentrations were re-evaluated after 1 month of CE treatment.

RESULTS

There was no significant difference in plasma GLP-2 concentrations between healthy cats (0.53 ng/ml) and cats with CE (0.52 ng/ml). GLP-2 concentrations in cats with CIE were not significantly different following 1 month of treatment (0.43 ng/ml) from those at initial presentation (0.44 ng/ml).

CONCLUSIONS AND RELEVANCE

GLP-2 can be successfully detected in the plasma of cats with CE. Based on the lack of differences observed between this population of CE cats and healthy cats, GLP-2 cannot be recommended as a biomarker of feline CE using this ELISA method. Further investigation of larger CE cat populations and analytic methods would be needed to determine the overall utility of GLP-2 evaluation in feline CE.

Lymphoma & Myeloproliferative Disease

Lymphoma and myeloproliferative diseases in horses are relatively uncommon. The clinical signs, prognosis, and treatment options depend upon the anatomic location and subtype. Significant gaps in knowledge remain regarding prevalence, pathogenesis of different subtypes, antemortem diagnostic tests, response to treatment, and standardized treatment protocols. However, treatment options are available, accessible on the farm, and could improve quality of life and prolong survival.

Serum electrolyte abnormalities in cats with chronic inflammatory enteropathy

BACKGROUND

Limited information is available on electrolyte abnormalities in cats with chronic inflammatory enteropathy (CIE).

HYPOTHESIS/OBJECTIVES

Report the prevalence of electrolyte abnormalities in cats with CIE compared to other gastrointestinal disorders, and determine their association with disease and outcome variables in cats with CIE.

ANIMALS

Three hundred twenty-eight client-owned cats from 2 referral hospitals: CIE (132), alimentary small cell lymphoma (29), acute gastroenteritis (48), and healthy controls (119).

METHODS

Retrospective study comparing serum electrolyte concentrations at time of diagnosis among the 4 groups of cats, and associations with clinical signs, intestinal mucosal fibrosis scores, treatment subclassification and outcome in CIE.

RESULTS

Cats with CIE had lower sodium and higher potassium concentrations and lower sodium: potassium ratios compared with healthy cats (P < .001, P = .01, and P < .001, respectively). Cats with CIE and a duodenal mucosal fibrosis score of 2 had lower sodium and lower total calcium concentrations compared with cats that had a score of 0 (P = .02 and P = .01). Cats with CIE and a colonic mucosal fibrosis score of 1 had higher potassium concentrations and lower sodium: potassium ratios compared with cats that had a score of 0 (P = .03 and P = .01). Cats with CIE that died as a result of their disease had higher potassium concentrations and lower sodium: potassium ratios compared to cats that were alive (P = .02 and P = .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

Electrolyte abnormalities occur with CIE and, in particular, in cats with higher fibrosis scores and worse outcomes. Further research should aim to determine the pathogenesis of these findings and identify novel therapeutic targets for cats with CIE.

Evidence-based veterinary medicine-potential, practice, and pitfalls

Understanding and incorporating evidence-based veterinary medicine (EBVM) into clinical practice and research continues to pose a challenge for our profession despite over 2 decades of increasing awareness of this concept. Reasons for this include a lack of understanding of its importance to the practice of medicine, veterinary literature that often fails to adhere to evidence-based standards, inadequate attention to teaching EBVM at the university level, and the inherent reluctance of clinicians to alter historical practice styles. For many practitioners, EBVM continues to be an abstract concept they believe requires advanced training in statistics and epidemiology resulting in them relying on less robust sources for clinical guidance. This unfortunately results in suboptimal care for our patients and delayed medical advancements for our profession. As part of the 20th anniversary of the founding of the Evidence-Based Veterinary Medicine Association (EBVMA), we are refocusing our efforts to highlight the need for dedicated teaching of EBVM at the university level, for rigorous adherence to established research reporting guidelines, for expansion of EBVM infrastructure, and for the provision of easily accessible tools that permit clinicians to incorporate EBVM into their daily practice. As the quality of veterinary literature improves, so too will development of more effective clinical practice guidelines that ultimately can be widely adopted if they are flexible enough to support the triadic relationship between veterinarians, our clients and our patients. Ultimately, EBVM is not an end unto itself, but rather a means to improve the quality of care we provide our patients.

Hypoalbuminaemia and its association with disease and clinical outcomes in cats

OBJECTIVES

To report the incidence of feline hypoalbuminaemia and characterise the distribution of presenting disease categories and pathoaetiologies of hypoalbuminaemia in cats. The secondary aim was to evaluate the relationship between hypoalbuminaemia and clinical outcomes.

MATERIALS AND METHODS

Medical records of cats with hypoalbuminaemia (<28.0 g/L, reference interval: 28.0 to 39.0 g/L) presenting to a veterinary teaching hospital over 5 years were retrospectively reviewed. The severity of hypoalbuminaemia was further stratified into mild (24.0 to 27.9 g/L), moderate (20.0 to 23.9 g/L) and severe (≤19.9 g/L) groups. The median albumin and severity groups were compared between the determined disease categories, pathoaetiologies and clinical outcomes.

RESULTS

The incidence of hypoalbuminaemia was 32.7% (533/1632). Gastrointestinal disease was the most common disease category associated with hypoalbuminaemia [154/533 (28.9%)], of which, 49.4% (76/154) of cats had gastrointestinal neoplasia. Neoplastic [159/533 (29.8%)] and inflammatory conditions [158/533 (29.6%)] were common pathoaetiologies noted. Statistically significant differences in the serum albumin between individual disease and pathoaetiological categories were found. Cats with moderate to severe hypoalbuminaemia had a statistically significantly longer hospitalisation period, cost of treatment and increased odds of death (odds ratio 2.4, 95% confidence interval: 1.3 to 4.6 and odds ratio 3.2, 95% confidence interval: 1.5 to 6.6, respectively).

CLINICAL SIGNIFICANCE

The incidence of feline hypoalbuminaemia in our study surpasses previous canine reports. Our findings support albumin as a negative acute phase protein in cats, with hypoalbuminaemia frequently associated with inflammatory disease. Hypoalbuminaemia also features prominently in cats with gastrointestinal neoplasia, indicating careful appraisal of the presence of protein-losing enteropathy is required in these cases. Finally, albumin is found to be a prognostic indicator in this study.

Proof-of-concept evaluation of next-generation sequencing-based liquid biopsy for non-invasive cancer detection in cats

This proof-of-concept evaluation demonstrates that next-generation sequencing-based liquid biopsy can detect genomic alterations in the blood of cats with cancer and the absence of such alterations in the blood of presumably cancer-free cats. Two cats with cytologically confirmed lymphoma and nine presumably cancer-free cats were included in this analysis. Whole blood was collected from each subject and samples were subjected to DNA extraction, library preparation, and next-generation sequencing. Both cancer-diagnosed subjects had somatic copy number variants (a "cancer signal") identified in cell-free DNA, suggesting the current presence of cancer in these subjects. All nine presumably cancer-free subjects had unremarkable genomic profiles, suggesting the absence of cancer in these subjects. Liquid biopsy using next-generation sequencing of cell-free DNA allows for blood-based detection of cancer-associated genomic alterations in cats. Such technology has the potential to offer considerable utility in veterinary medicine, particularly for the non-invasive prioritization of small cell intestinal lymphoma versus inflammatory bowel disease in cats with gastrointestinal signs. This study lays the foundation for future studies to fully validate this type of testing for use in clinical practice.

Evaluation of the fatty acid-based erythrocyte membrane lipidome in cats with food responsive enteropathy, inflammatory bowel disease and low-grade intestinal T-cell lymphoma

Feline chronic enteropathies (FCE), include food-responsive-enteropathy (FRE), inflammatory bowel disease (IBD), and low-grade intestinal T-cell lymphoma (LGITL), and are common causes of chronic gastrointestinal signs in cats. Distinguishing between different subgroups of FCE can be challenging due to the frequent overlap of anamnestic, clinical, and laboratory data. While dysregulation in lipid metabolism has been reported in humans and dogs with chronic IBD, similar changes in cats are not yet completely understood. Assessing the fatty acid (FA) profile of red blood cell (RBC) membranes offers a valuable method for evaluating the quantity and quality of structural and functional molecular components in the membranes. Therefore, this study aimed to examine the FA composition of RBC membranes in FCE in comparison to healthy cats (HC). Gas-chromatography was used to quantitatively analyze a cluster of 11 FA, and based on these results, parameters of lipid homeostasis and enzyme activity indexes were calculated. A total of 41 FCE cats (17 FRE, 15 IBD, 9 LGITL) and 43 HC were enrolled. In FCE cats, the values of docosapentaenoic acid (p = 0.0002) and docosahexaenoic acid (p = 0.0246), were significantly higher, resulting in an overall increase in ω-3 polyunsaturated fatty acids (PUFA) (p = 0.006), and that of linoleic acid (p = 0.0026) was significantly lower. Additionally, FCE cats exhibited an increased PUFA balance (p = 0.0019) and Δ6-desaturase index (p = 0.0151), along with a decreased ω-6/ω-3 ratio (p = 0.0019). No differences were observed among cats affected by FRE, IBD and LGITL. Like humans and dogs, the results of this study indicate that FCE cats also display changes in their FA lipid profile at the level of the RBC membrane. The non-invasive analysis of RBC membrane shows promise as a potential tool for gaining a better understanding of lipid imbalances in this disease.

The diagnostic relevance of mesenteric lymph node biopsy in small intestinal lymphoma in cats

BACKGROUND

Regional lymph nodes are frequently sampled in cats with suspected intestinal lymphoma; however, their diagnostic value has not been explored.

OBJECTIVES

To investigate whether histologic and immunohistochemical analysis of mesenteric lymph nodes correlates with the diagnosis of intestinal lymphoma in cats.

ANIMALS

One hundred 2 client-owned cats diagnosed with intestinal lymphoma.

METHODS

Retrospective study. The inclusion criteria required a full-thickness biopsy of the small intestine and concurrent excision of mesenteric lymph nodes. Histologic and immunophenotypic analyses were performed on intestinal biopsies and corresponding lymph nodes. Selected nodal samples diagnosed with reactive lymph nodes underwent clonality testing.

RESULTS

Transmural T-cell lymphomas, encompassing small and large cell types, were predominant (64 cases, 62.7%), with large B-cell lymphomas being more frequently transmural (68.8%) than mucosal (31.2%). Among all lymph nodes examined, 44 (43.1%; 95% CI: 33.9%-52.8%) exhibited neoplastic infiltration. Among cases of small cell lymphoma, 51 out of 72 (70.8%; 95% CI: 59.4%-80.1%) showed no nodal involvement. Clonality results correctly identified 19/30 (63.3%; 95% CI: 45.5%-78.2%) reactive lymph nodes. Concerns were raised regarding clonal identification in the remaining cases and potential misdiagnoses based on phenotypic characteristics.

CONCLUSION AND CLINICAL IMPORTANCE

The study underscores the potential drawbacks of relying solely on mesenteric lymph nodes for diagnosing intestinal lymphomas in cats, particularly small cell subtypes. It emphasizes the importance of full-thickness biopsies for assessing transmural infiltration and recommends caution when utilizing mesenteric lymph nodes for histologic, immunohistochemical and clonality evaluations in mucosal lymphomas. Despite limitations, this research highlights the need for comprehensive diagnostic strategies in cats with intestinal lymphoma.

Short colon syndrome in cats

BACKGROUND

Shortening of the colon has been described in cats, but its imaging and clinicopathological features remain poorly understood.

OBJECTIVES

Description of the signalment, clinical presentation, imaging, endoscopic and histological features of short colon syndrome in cats.

ANIMALS

Ninety-three cats diagnosed with short colon.

METHODS

Multi-institutional, descriptive, retrospective case series study. Medical records were searched for a diagnosis of short colon on abdominal ultrasonography, computed tomography, endoscopy, autopsy, or a combination of these modalities.

RESULTS

The median age of included cats was 12 years at the time of diagnosis. Diarrhea was the most common clinical sign (60/92; 65%), followed by vomiting (36/92; 39%), weight loss (36/92; 39%), and inappetence (24/92; 26%). Thirteen percent of cats (12/92) had no signs of gastrointestinal disease at the time of diagnosis. In addition to a shortened colonic length, 79% (66/84) of cats had concomitant colonic thickening on ultrasonographic examination. On colonoscopy, mucosal ulcerations of the colonic wall were seen in 39% (9/23) of cats. Histopathologically, all cats but 1 (diagnosed simultaneously with colonic small cell lymphoma) had lymphoplasmacytic colitis, and when small intestinal biopsies were performed, concurrent lymphoplasmacytic enteritis or small cell lymphoma of the small intestine.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lymphoplasmacytic colitis is seen commonly in cats with short colon, suggesting a potential link between these entities.

Immunophenotype investigation in feline intestinal non-B-cell lymphoma

Lymphoma is the most common tumour of domestic cats, developing most frequently in the small intestine. Feline small intestinal lymphoma predominantly demonstrates a T-cell immunophenotype identified by standard immunopositivity for T cells with CD3 or immunopositivity for B cells with CD20. In contrast, a wide spectrum of immunohistochemical antibodies are applied in humans to diagnose the various specific lymphoma subtypes according to the WHO classification. Our aim was to augment our knowledge of immunophenotypes in feline non-B-cell lymphomas forming macroscopic masses in the intestinal tract. We evaluated the combined immunohistochemistry and flow cytometry findings from 15 cases. Neoplastic lymphoid cells were immunopositive for CD3 in 93% (14/15), granzyme B in 87% (13/15), CD5 in 20% (3/15), CD8 in 13% (2/15), CD4 in 7% (1/15) and CD56 in 7% (1/15) of cases. Cytotoxic granules indicating a cytotoxic origin of the neoplastic cells were identified by histopathology only in 13% (2/15) and by cytology in 47% (7/15) of the cases. Without immunohistochemical labelling of the cytotoxic protein granzyme B, the cytotoxic status would have been missed in 46% (6/13) of the cytological and in 85% (11/13) of the histopathological slides. These findings suggest that more complex immunophenotyping may advance our understanding and help prognosticate small intestinal T-cell lymphoma in cats.

The Importance of Intestinal Microbiota and Dysbiosis in the Context of the Development of Intestinal Lymphoma in Dogs and Cats

Recent advancements have significantly enhanced our understanding of the crucial role animal microbiomes play in veterinary medicine. Their importance in the complex intestinal environment spans immune modulation, metabolic homeostasis, and the pathogenesis of chronic diseases. Dysbiosis, a microbial imbalance, can lead to a range of diseases affecting both individual organs and the entire organism. Microbial disruption triggers inflammatory responses in the intestinal mucosa and disturbs immune homeostasis, increasing susceptibility to toxins and their metabolites. These dynamics contribute to the development of intestinal lymphoma, necessitating rigorous investigation into the role of microbiota in tumorigenesis. The principles explored in this study extend beyond veterinary medicine to encompass broader human health concerns. There are remarkable parallels between the subtypes of lymphoproliferative disorders in animals and humans, particularly Hodgkin's lymphoma and non-Hodgkin's lymphoma. Understanding the etiology of a cancer of the lymphatic system formation is critical for developing both preventive strategies and therapeutic interventions, with the potential to significantly improve patient outcomes. The aim of this study is to discuss the optimal composition of the microbiome in dogs and cats and the potential alterations in the microbiota during the development of intestinal lesions, particularly intestinal lymphoma. Molecular and cellular analyses are also incorporated to detect inflammatory changes and carcinogenesis. A review of the literature on the connections between the gut microbiome and the development of lymphomas in dogs and cats is presented, along with potential diagnostic approaches for these cancers.

Fecal microbiota and concentrations of long-chain fatty acids, sterols, and unconjugated bile acids in cats with chronic enteropathy

Feline chronic enteropathies (FCE) are common causes of chronic gastrointestinal signs in cats and include different diseases such as food-responsive enteropathy (FRE), inflammatory bowel diseases (IBD), and low-grade intestinal T-cell lymphoma (LGITL). Although changes in intestinal microbiota and fecal metabolites have been reported in dogs and humans with chronic enteropathy, research in cats has been limited. Therefore, this study aimed to evaluate the fecal microbiota and lipid-related fecal metabolites in cats with FCE to a clinically healthy comparison group (CG). A total of 34 cats with FCE (13 FRE, 15 IBD, and 6 LGITL) and 27 cats in the CG were enrolled in this study. The fecal microbiota was evaluated by the qPCR-based feline Dysbiosis Index (DI). The feline DI in cats with CE (median: 1.3, range: -2.4 to 3.8) was significantly higher (p < 0.0001) compared to CG (median: - 2.3, Range: -4.3 to 2.3), with no difference found among the FCE subgroups. The fecal abundances of Faecalibacterium (p < 0.0001), Bacteroides (p < 0.0001), Fusobacterium (p = 0.0398), Bifidobacterium (p = 0.0004), and total bacteria (p = 0.0337) significantly decreased in cats with FCE. Twenty-seven targeted metabolites were measured by gas chromatography-mass spectrometry, including long-chain fatty acids (LCFAs), sterols, and bile acids (BAs). Fecal concentrations of 5 of 12 LCFAs were significantly increased in cats with FCE compared to CG. Fecal concentrations of zoosterol (p = 0.0109), such as cholesterol (p < 0.001) were also significantly increased in cats with FCE, but those of phytosterols were significantly decreased in this group. No differences in fecal BAs were found between the groups. Although no differences were found between the four groups, the fecal metabolomic pattern of cats with FRE was more similar to that of the CG than to those with IBD or LGITL. This could be explained by the mild changes associated with FRE compared to IBD and LGITL. The study showed changes in intestinal microbiota and alteration of fecal metabolites in FCE cats compared to the CG. Changes in fecal lipids metabolites suggest a dysmetabolism of lipids, including LCFAs, sterols, and unconjugated BAs in cats with CE.

Description and Characterization of Different Types of Lymphoma in Cats in Hong Kong

This study aimed to characterize and describe the different lymphoma types and anatomical forms in cats in Hong Kong. The clinical and histopathological data of cats diagnosed with lymphoma by cytology and/or histopathology were collected from a large diagnostic laboratory in Hong Kong. In total, 444 cats were diagnosed with lymphoma over four years (2019-2022). Like other countries where there is a low prevalence of FeLV infection, the predominant form of lymphoma was gastrointestinal (abdominal). Nasopharyngeal and peripheral nodal lymphoma were the second and third most common forms of lymphoma. The large cell/high-grade lymphoma type was much more common than the low-grade/small cell lymphoma in the study population. Domestic short hair was the most commonly affected breed in our study (n = 259/444). Among the cats with identified T/B-cell status, B-cell lymphoma (n = 61/81) prevailed as the most common phenotype. This study describes and characterizes the different types of feline lymphoma in cats in Hong Kong, adding valuable information to the body of knowledge.

Flowcytometric data of intermediate-large cell gastrointestinal lymphoma presenting a gross mass in 32 cats - "let them glow in the flow"

Gastrointestinal lymphoma is the most common form of lymphoma in domestic cats. Aggressive phenotypes are much less common but do bear and unfavorable prognosis. Immunophenotyping by flow cytometry (FCM) is not systematically performed in these patients, because of difficulties in the acquisition of suitable sample material from the gastrointestinal tract. A multimodal diagnostic approach is recommended to improve identification of subtypes targeting patient tailored therapeutic strategies. The aim of this prospective study was to present results of multicolor FCM immunophenotyping in surgically removed gastrointestinal mass and relate them with histopathology using the World Health Organization (WHO) classification and clonality PCR testing. Thirty-two patients were included. Eight cats (25%) had gastric, 23 (72%) had intestinal lymphoma and 1 (3%) had gastric/jejunal lymphoma. Intestinal lymphoma sites were represented by 18 small intestinal, 4 ileocaecal, 1 large intestinal. All gastric lymphomas were diffuse large B-cell lymphoma (DLBCL). Small intestinal lymphomas were 10 enteropathy associated T-cell lymphoma type I (EATL I), 2 enteropathy associated T-cell lymphoma type II (EATL II), 2 peripheral T-cell lymphoma (PTCL), 3 DLBCL and one DLBCL+EATL II. The most common small intestinal FCM T-cell phenotype was CD3+CD21- CD4-CD8-CD18+ CD5-CD79- in 7/10 EATL I and one EATL II. The most frequent FCM B-cell phenotype was CD3-CD21+ CD4-CD8-CD18+ CD5-CD79+ in 13/17 DLBCL and the DLBCL+EATL II. Clonality PCR results were positive in 87.5% (28/32) of all cases. No cross-lineage rearrangement was observed. IHC and FCM results agreed in 87.5% (28/32) of all cases. When all 3 methods were combined, consistent results were seen in 75% (24/32). This is the first demonstration of a multicolor FCM approach set in context to the gold standard histopathology and clonality testing results.

Gut microbiota in cats with inflammatory bowel disease and low-grade intestinal T-cell lymphoma

In cats and humans, several physiological and environmental factors have been shown to alter the gut microbiota of healthy individuals. Cats share several diseases with humans such as inflammatory bowel diseases and low-grade intestinal T-cell lymphoma. The physiopathology of these chronic enteropathies is poorly understood but may involve disequilibrium of the gut microbiota composition and disruption of normal microbiome activity profiles. These disorders are increasingly diagnosed in the feline species due to improved medicalization and easier access to endoscopy in veterinary practice. This review addresses the current data on the gut microbiota of cats in health and in chronic enteropathies. Such functional analysis will help the advancement of innovative diagnostic tools and targeted therapeutic strategies.

Treatment success in cats with chronic enteropathy is associated with a decrease in fecal calprotectin concentrations

Feline chronic enteropathies (FCE) are challenging to diagnose and monitor for progression and response to treatment. Fecal calprotectin might be a useful non-invasive marker to evaluate clinical endpoints of therapeutic monitoring in FCE. We evaluated fecal calprotectin concentrations in cats with FCE before and after initiation of treatment comprised of immunomodulation and/or dietary intervention. Included were 17 cats with FCE and 18 healthy controls. Clinical investigation of FCE cases included clinical severity grading (feline chronic enteropathy activity index, FCEAI) in all cats, abdominal ultrasonography in 15 cats, and gastrointestinal biopsies in 6 cats. Fecal calprotectin was measured in samples from 12 cats with FCE before treatment, all 17 FCE cats ≥6 weeks after treatment initiation, and all healthy controls. Fecal calprotectin concentrations in FCE cases before treatment (median: 61 μg/g) were significantly higher than after treatment initiation (median: 15 μg/g; p = 0.0098) and compared to controls (median: 6 μg/g; p = 0.0235) and correlated with the FCEAI scores (ρ = 0.54, p = 0.0316). Fecal calprotectin concentrations after treatment initiation were higher with more severe duodenal/proximal jejunal pathology (ρ = 0.83, p = 0.0427) and shorter intervals between sampling time points (ρ = -0.54, p = 0.0250). Relevant decreases in initially increased fecal calprotectin concentrations are seen in cats with FCE on varying treatment strategies that significantly improve or have remission of clinical signs. This supports the utility of fecal calprotectin as a surrogate biomarker to assess disease severity in FCE cases. Further studies need to evaluate fecal calprotectin concentrations longitudinally in relation to mucosal healing vs. clinical response.

Unbiased serum metabolomic analysis in cats with naturally occurring chronic enteropathies before and after medical intervention

Chronic enteropathies (CE) are common disorders in cats and the differentiation between the two main underlying diseases, inflammatory bowel disease (IBD) and low-grade intestinal T-cell lymphoma (LGITL), can be challenging. Characterization of the serum metabolome could provide further information on alterations of disease-associated metabolic pathways and may identify diagnostic or therapeutic targets. Unbiased metabolomics analysis of serum from 28 cats with CE (14 cats with IBD, 14 cats with LGITL) and 14 healthy controls identified 1,007 named metabolites, of which 129 were significantly different in cats with CE compared to healthy controls at baseline. Random Forest analysis revealed a predictive accuracy of 90% for differentiating controls from cats with chronic enteropathy. Metabolic pathways found to be significantly altered included phospholipids, amino acids, thiamine, and tryptophan metabolism. Several metabolites were found to be significantly different between cats with IBD versus LGITL, including several sphingolipids, phosphatidylcholine 40:7, uridine, pinitol, 3,4-dihydroxybenzoic acid, and glucuronic acid. However, random forest analysis revealed a poor group predictive accuracy of 60% for the differentiation of IBD from LGITL. Of 129 compounds found to be significantly different between healthy cats and cats with CE at baseline, 58 remained different following treatment.

Effects of a veterinary gastrointestinal diet on fecal characteristics, metabolites, and microbiota concentrations of adult cats treated with metronidazole

Antibiotics are used to treat gastrointestinal diseases or infections but are known to negatively affect stool quality and gut microbiota in cats and dogs. Therefore, identifying dietary strategies that may aid in antibiotic recovery is of interest. The objective of this study was to determine how a veterinary gastrointestinal diet affected the fecal characteristics, microbiota, and metabolite and bile acid (BA) concentrations of cats recovering from metronidazole administration. Twenty-four healthy adult cats were used in an 8-wk completely randomized design study. During a 2-wk baseline, all cats consumed a leading grocery brand diet (GBD). Over the next 2 wk, cats consumed GBD and received metronidazole (20 mg/kg body weight twice daily). At week 4, cats were randomly allotted to one of 2 treatments [GBD; BLUE Natural Veterinary Diet GI Gastrointestinal Support (BB)] and fed for 4 wk. Fecal scores were recorded daily and fresh fecal samples were collected at weeks 2, 4, 5, 6, 7, and 8 for measurement of pH, dry matter (DM) %, metabolites, and microbiota. Microbiota was analyzed by 16S rRNA gene sequencing and qPCR, which was used to calculate dysbiosis index. Data were analyzed as repeated measures using the Mixed Models procedure of SAS 9.4, testing for effects of diet, time and diet*time. Metronidazole had dramatic effects on all outcomes, including increased fecal scores (looser stools), reduced fecal pH and DM%, reduced fecal short-chain fatty acid, branched-chain fatty acid, ammonia, phenol, and indole concentrations, and altered fecal BA concentrations (increased primary BA; reduced secondary BA). Metronidazole reduced fecal bacterial alpha diversity, increased dysbiosis index, and altered the relative abundance of 78 bacterial genera. Fecal outcomes partially recovered over the next 4 wk, with some being impacted by diet. Fecal acetate concentrations were higher after metronidazole in cats fed BB. Dysbiosis index and alpha diversity measures slowly recovered over 4 wk, without diet differences. Recovery of 16 bacterial genera was impacted by diet. Fecal BA profiles demonstrated a prolonged impairment of primary to secondary BA conversion, with cholic acid being lower after metronidazole in cats fed BB. In conclusion, our data demonstrate that metronidazole is a powerful antibiotic that has long-lasting effects on the fecal microbiota and metabolites of cats. Outcome variables slowly recovered over time, but a gastrointestinal diet may aid in recovery.

Chronic Inflammatory Enteropathy and Low-Grade Intestinal T-Cell Lymphoma Are Associated with Altered Microbial Tryptophan Catabolism in Cats

Chronic inflammatory enteropathy (CIE) and low-grade intestinal T-cell lymphoma (LGITL) are common chronic enteropathies (CE) in cats. Enteric microbiota dysbiosis is implicated in the pathogenesis of CE; however, the mechanisms of host-microbiome interactions are poorly understood in cats. Microbial indole catabolites of tryptophan (MICT) are gut bacterial catabolites of tryptophan that are hypothesized to regulate intestinal inflammation and mucosal barrier function. MICTs are decreased in the sera of humans with inflammatory bowel disease and previous studies identified altered tryptophan metabolism in cats with CE. We sought to determine whether MICTs were decreased in cats with CE using archived serum samples from cats with CIE (n = 44) or LGITL (n = 31) and healthy controls (n = 26). Quantitative LC-MS/MS was used to measure serum concentrations of tryptophan, its endogenous catabolites (kynurenine, kynurenate, serotonin) and MICTs (indolepyruvate, indolealdehyde, indoleacrylate, indoleacetamide, indoleacetate, indolelactate, indolepropionate, tryptamine). Serum concentrations of tryptophan, indolepropionate, indoleacrylate, indolealdehyde, indolepyruvate, indolelactate were significantly decreased in the CIE and LGITL groups compared to those in healthy controls. Indolelactate concentrations were significantly lower in cats with LGITL compared to CIE (p = 0.006). Significant correlations were detected among serum MICTs and cobalamin, folate, fPLI, and fTLI. Our findings suggest that MICTs are promising biomarkers to investigate the role of gut bacteria in the pathobiology of chronic enteropathies in cats.

Faecal microbiota and fatty acids in feline chronic enteropathy

BACKGROUND

Feline chronic enteropathy is a set of disorders defined as the presence of clinical signs of gastrointestinal disease for at least three weeks. The most common final diagnoses are inflammatory bowel disease and alimentary small cell lymphoma. The etiopathogenesis of these diseases is incompletely understood; however, it is hypothesised that they involve a combination of factors, including altered composition and/or functionality of the intestinal microbiome. An important factor in the interplay of the microbiome and host is the production of short- and branched-chain fatty acids.  The aim of this study was to evaluate the possible differences in faecal microbiota diversity, composition and fatty acid production between cats suffering from chronic enteropathy and healthy cats. Sixteen cats suffering from chronic enteropathy and fourteen healthy control cats were enrolled in the study. The microbiota compositions of faecal samples were analysed by using next-generation amplicon sequencing of the V3V4 fragment of the 16S rRNA gene. Fatty acids were evaluated by high-performance liquid chromatography.

RESULTS

Both the alpha and beta diversities were significantly lower in samples obtained from cats with chronic enteropathy. The relative abundance of the phylum Proteobacteria, orders Lactobacillales and Enterobacterales, family Enteriobacteriaceae and genus Escherichia Shigella were higher in diseased cats, whereas the abundance of the phylum Bacteroidota and order Peptococcales were higher in control cats. The faecal concentrations of short-chain fatty acids were higher in cats with chronic enteropathy, with lower propionate proportions and higher butyrate proportions.

CONCLUSION

The study revealed alterations in microbiota compositions and short-chain fatty acid concentration in cats suffering from chronic enteropathy, which is an important finding both for research on the pathogenesis of the disease and for potential therapeutic interventions in the form of faecal microbiota transplantation and/or probiotic supplementation.

Case report: Lymphocytic-plasmacytic and eosinophilic enterocolitis presented with marked eosinophilia and basophilia in a cat

Inflammatory bowel disease is a common condition in cats, characterized by recurring gastrointestinal signs with histologic evidence of intestinal inflammation. A 9-month-old neutered male Sphynx cat was presented with a 5-week history of vomiting and hematochezia. Conservative patient management with a therapeutic gastrointestinal formula, antibiotics, and antiemetics resulted in a positive response to treatment, with relapse of signs when the medications were discontinued. A new finding of marked eosinophilia and basophilia was identified 3 months after the initial presentation. Colonoscopy revealed cecal erosions and a surgical biopsy with histopathology confirmed a diagnosis of lymphocytic-plasmacytic and eosinophilic enterocolitis. For this diagnosis, the patient was treated with prednisolone, tylosin, and metronidazole. Antibiotics were gradually tapered as the cat showed clinical improvement. The patient showed resolution of the gastrointestinal signs, and the numbers of eosinophils and basophils returned within the reference range 8 weeks after the treatment began. Basophilia and eosinophilia has been reported in conjunction with feline T-cell lymphoma. However, marked basophilia accompanying eosinophilia is extremely rare in cats with inflammatory bowel disease. We herein provide clinical details, including ultrasonography, endoscopy, histopathology, and disease course of feline lymphocytic-plasmacytic and eosinophilic enterocolitis with marked basophilia and eosinophilia. This case highlights the importance of considering enteritis as potential diagnoses when eosinophilia and basophilia are concurrently observed in cats.

Ultrasonography and Sonoelastography Characteristics of Benign vs. Malignant Mesenteric Lymph Nodes in Cats: An Update

(1) Background: Strain elastography (SE) is an ultrasound-based technique able to non-invasively assess tissue elasticity, with malignant tissues being stiffer than normal tissues. The purpose of the study was to evaluate the diagnostic performance of SE to differentiate feline mesenteric benign and malignant lymph nodes (LNs) using a multivariate approach including both SE results and B-mode ultrasound and color Doppler findings. (2) Methods: Feline enlarged mesenteric LNs were evaluated using B-mode ultrasound, color Doppler ultrasonography, and SE. Short-to-long axis ratios, borders, echogenicity, hilum, vascular flow distribution, elastographic patterns, and strain ratios were recorded. Histological and/or cytological diagnosis was available for each LN. (3) Results: A total of 88 LNs were included, 46 (52.3%) benign and 42 (47.7%) malignant; in the benign group, 40 LNs had a diagnosis of reactive hyperplasia (group A) and 6 eosinophilic sclerosing lymphadenitis (group B), while in the malignant group 42 had a diagnosis of lymphoma (group C). The principal component analysis approach showed evidence that by combining B-mode- and color Doppler-based scores with SE scores, the three groups of LNs can be accurately distinguished. (4) Conclusions: Our results demonstrate that a multivariate sonographic approach combining B-mode ultrasound, color Doppler ultrasonography, and SE can accurately distinguish benign from malignant LNs, thus helping in the clinical advice of feline patients.