Safety profile and effects on the peripheral immune response of fecal microbiota transplantation in clinically healthy dogs

BACKGROUND

Fecal microbiota transplantation (FMT) is increasingly used for gastrointestinal and extra-gastrointestinal diseases in veterinary medicine. However, its effects on immune responses and possible adverse events have not been systematically investigated.

HYPOTHESIS/OBJECTIVES

Determine the short-term safety profile and changes in the peripheral immune system after a single FMT administration in healthy dogs.

ANIMALS

Ten client-owned, clinically healthy dogs as FMT recipients, and 2 client-owned clinically healthy dogs as FMT donors.

METHODS

Prospective non-randomized clinical trial. A single rectal enema of 5 g/kg was given to clinically healthy canine recipients. During the 28 days after FMT administration, owners self-reported adverse events and fecal scores. On Days 0 (baseline), 1, 4, 10, and 28 after FMT, fecal and blood samples were collected. The canine fecal dysbiosis index (DI) was calculated using qPCR.

RESULTS

No significant changes were found in the following variables: CBC, serum biochemistry, C-reactive protein, serum cytokines (interleukins [IL]-2, -6, -8, tumor necrosis factor [TNF]-α), peripheral leukocytes (B cells, T cells, cluster of differentiation [CD]4+ T cells, CD8+ T cells, T regulatory cells), and the canine DI. Mild vomiting (n = 3), diarrhea (n = 4), decreased activity (n = 2), and inappetence (n = 1) were reported, and resolved without intervention.

CONCLUSIONS AND CLINICAL IMPORTANCE

Fecal microbiota transplantation did not significantly alter the evaluated variables and recipients experienced minimal adverse events associated with FMT administration. Fecal microbiota transplantation was not associated with serious adverse events, changes in peripheral immunologic variables, or the canine DI in the short-term.

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.

Temporal Variability of the Dominant Fecal Microbiota in Healthy Adult Cats

While shifts in gut microbiota have been studied in diseased states, the temporal variability of the microbiome in cats has not been widely studied. This study investigated the temporal variability of the feline dysbiosis index (DI) and the abundance of core bacterial groups in healthy adult cats. The secondary aim was to evaluate the relationship between the fecal abundance of Clostridium hiranonis and the fecal concentrations of unconjugated bile acids. A total of 142 fecal samples collected from 17 healthy cats were prospectively included: nine cats with weekly collection over 3 weeks (at least four time points), five cats with monthly collection over 2 months (three time points), and three cats with additional collections for up to 10 months. The DI remained stable within the reference intervals over two months for all cats (Friedman test, p > 0.2), and 100% of the DI values (n = 142) collected throughout the study period remained within the RI. While some temporal individual variation was observed for individual taxa, the magnitude was minimal compared to cats with chronic enteropathy and antibiotic exposure. Additionally, the abundance of Clostridium hiranonis was significantly correlated with the percentage of fecal primary bile acids, supporting its role as a bile acid converter in cats.

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.

Polyautoimmunity manifest as inflammatory myopathy, uveitis, and progressive cutaneous depigmentation in a mixed breed dog: a case report

BACKGROUND

Polyautoimmunity is the expression of more than one autoimmune disease in a single patient. This report documents polyautoimmunity in a mixed breed dog with concurrent uveitis, cutaneous depigmentation, and inflammatory myopathy.

CASE PRESENTATION

A 1-year-old male neutered mixed breed dog was presented for progressive generalized leukotrichia and leukoderma, bilateral panuveitis, and masticatory muscle atrophy. The latter progressed to myositis of lingual, pharyngeal, and masticatory muscles confirmed by biopsy. Temporalis muscle was completely replaced by adipose and fibrous tissue, and necrotic myofibers with extensive infiltration of mononuclear cells indicated active myositis of lingual muscle. Skin biopsies showed severe melanin clumping in epidermis, hair follicles, and hair shafts, and perifollicular pigmentary incontinence. Uveitis, depigmentation, and myositis affecting the masticatory, pharyngeal, and tongue muscles were diagnosed based on clinical, histological, and laboratory findings.

CONCLUSIONS

To the authors' knowledge, this is the first report of concurrent uveitis, progressive cutaneous depigmentation, and inflammatory myopathy in a dog.

Fecal Concentrations of Long-Chain Fatty Acids, Sterols, and Unconjugated Bile Acids in Cats with Chronic Enteropathy

Chronic enteropathy (CE) in cats encompasses food-responsive enteropathy, chronic inflammatory enteropathy (or inflammatory bowel disease), and low-grade intestinal T-cell lymphoma. While alterations in the gut metabolome have been extensively studied in humans and dogs with gastrointestinal disorders, little is known about the specific metabolic profile of cats with CE. As lipids take part in energy storage, inflammation, and cellular structure, investigating the lipid profile in cats with CE is crucial. This study aimed to measure fecal concentrations of various fatty acids, sterols, and bile acids. Fecal samples from 56 cats with CE and 77 healthy control cats were analyzed using gas chromatography-mass spectrometry, targeting 12 fatty acids, 10 sterols, and 5 unconjugated bile acids. Fecal concentrations of nine targeted fatty acids and animal-derived sterols were significantly increased in cats with CE. However, fecal concentrations of plant-derived sterols were significantly decreased in cats with CE. Additionally, an increased percentage of primary bile acids was observed in a subset of cats with CE. These findings suggest the presence of lipid maldigestion, malabsorption, and inflammation in the gastrointestinal tract of cats with CE. Understanding the lipid alterations in cats with CE can provide insights into the disease mechanisms and potential future therapeutic strategies.

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

BACKGROUND

Lymphoplasmacytic enteritis (LPE) and low-grade intestinal T cell lymphoma (LGITL) are common diseases in older cats, but their diagnosis and differentiation remain challenging.

OBJECTIVES

To summarize the current literature on etiopathogenesis and diagnosis of LPE and LGITL in cats and provide guidance on the differentiation between LPE and LGITL in cats. To provide statements established using evidence-based approaches or where such evidence is lacking, statements based on consensus of experts in the field.

ANIMALS

None.

METHODS

A panel of 6 experts in the field (2 internists, 1 radiologist, 1 anatomic pathologist, 1 clonality expert, 1 oncologist) with the support of a human medical immunologist, was formed to assess and summarize evidence in the peer-reviewed literature and complement it with consensus recommendations.

RESULTS

Despite increasing interest on the topic for clinicians and pathologists, few prospective studies were available, and interpretation of the pertinent literature often was challenging because of the heterogeneity of the cases. Most recommendations by the panel were supported by a moderate or low level of evidence. Several understudied areas were identified, including cellular markers using immunohistochemistry, genomics, and transcriptomic studies.

CONCLUSIONS AND CLINICAL IMPORTANCE

To date, no single diagnostic criterion or known biomarker reliably differentiates inflammatory lesions from neoplastic lymphoproliferations in the intestinal tract of cats and a diagnosis currently is established by integrating all available clinical and diagnostic data. Histopathology remains the mainstay to better differentiate LPE from LGITL in cats with chronic enteropathy.

Clinical utility of an immunoglobulin A-based serological panel for the diagnosis of chronic enteropathy in dogs

BACKGROUND

A panel of IgA-based serologic assays might aid in the diagnosis of chronic enteropathy (CE) in dogs, a syndrome encompassing conditions such as food-responsive enteropathy, immunosuppressant-responsive enteropathy, and inflammatory bowel disease (also referred to as chronic inflammatory enteropathy). However, it is unclear whether these biomarkers discriminate between CE and other types of primary intestinal disorders.

OBJECTIVES

To evaluate a diagnostic panel that measures serum concentrations of IgA directed against OmpC (ACA), canine calprotectin (ACNA), and gliadin-derived peptides (AGA) in dogs with well-characterized intestinal diseases.

ANIMALS

Fifty-five dogs with primary intestinal disease.

METHODS

Serum ACA, ACNA, and AGA concentrations were measured in 30 dogs with CE and 25 dogs with other intestinal diseases (non-CE population), including histoplasmosis, parasitism, E. coli-associated granulomatous colitis, and lymphoma. Serum IgA concentrations were compared among populations, and sensitivities and specificities were calculated using laboratory-provided cut-points.

RESULTS

Twenty-six of 30 (87%) CE dogs and 21 of 25 (84%) non-CE dogs had abnormal concentrations (intermediate or high) of at least 2 markers; these proportions were not significantly different (P = .99). A serum ACA concentration ≥15 EU/mL was 86.7% (95% confidence interval [CI], 69.3%-96.2%) sensitive and 24.0% (95% CI, 9.4%-45.1%) specific for CE diagnosis. High AGA concentrations were observed in 16 of 25 (64%) non-CE dogs.

CONCLUSIONS AND CLINICAL IMPORTANCE

The evaluated serologic markers were poorly specific for CE diagnosis, which raises concerns that their use in clinical practice might lead to misdiagnoses and delayed or even detrimental treatments in dogs with non-CE intestinal diseases.

Utility of fluorescence imitating brightfield imaging microscopy for the diagnosis of feline chronic enteropathy

Fluorescence imitating brightfield imaging (FIBI) is a novel microscopy method that allows for real-time, nondestructive, slide-free tissue imaging of fresh, formalin-fixed, or paraffin-embedded tissue. The nondestructive nature of the technology permits tissue preservation for downstream analyses. The objective of this observational study was to assess the utility of FIBI compared with conventional hematoxylin and eosin (H&E)-stained histology slides in feline gastrointestinal histopathology. Formalin-fixed paraffin-embedded full-thickness small intestinal tissue specimens from 50 cases of feline chronic enteropathy were evaluated. The ability of FIBI to evaluate predetermined morphological features (epithelium, villi, crypts, lacteals, fibrosis, submucosa, and muscularis propria) and inflammatory cells was assessed on a 3-point scale (0 = FIBI cannot identify the feature; 1 = FIBI can identify the feature; 2 = FIBI can identify the feature with more certainty than H&E). H&E and FIBI images were also scored according to World Small Animal Veterinary Association (WSAVA) Gastrointestinal Standardization Group guidelines. FIBI identified morphological features with similar or, in some cases, higher confidence compared with H&E images. The identification of inflammatory cells was less consistent. FIBI and H&E images showed an overall poor agreement with regard to the assigned WSAVA scores. While FIBI showed an equal or better ability to identify morphological features in intestinal biopsies, its ability to identify inflammatory cells is currently inferior compared with H&E-based imaging. Future studies on the utility of FIBI as a diagnostic tool for noninflammatory histopathologic lesions are warranted.

Dysbiosis index to evaluate the fecal microbiota in healthy cats and cats with chronic enteropathies

OBJECTIVES

Previous studies have identified various bacterial taxa that are altered in cats with chronic enteropathies (CE) vs healthy cats. Therefore, the aim of this study was to develop a targeted quantitative molecular method to evaluate the fecal microbiota of cats.

METHODS

Fecal samples from 80 client-owned healthy cats and 68 cats with CE were retrospectively evaluated. A panel of quantitative PCR (qPCR) assays was used to measure the fecal abundance of total bacteria and seven bacterial taxa: Bacteroides, Bifidobacterium, Clostridium hiranonis, Escherichia coli, Faecalibacterium, Streptococcus and Turicibacter. The nearest centroid classifier algorithm was used to calculate a dysbiosis index (DI) based on these qPCR abundances.

RESULTS

The abundances of total bacteria, Bacteroides, Bifidobacterium, C hiranonis, Faecalibacterium and Turicibacter were significantly decreased, while those of E coli and Streptococcus were significantly increased in cats with CE (P <0.027 for all). The DI in cats with CE was significantly higher compared with healthy cats (P <0.001). When the cut-off value of the DI was set at 0, it provided 77% (95% confidence interval [CI] 66-85) sensitivity and 96% (95% CI 89-99) specificity to differentiate the microbiota of cats with CE from those of healthy cats. Fifty-two of 68 cats with CE had a DI >0.

CONCLUSIONS AND RELEVANCE

A qPCR-based DI for assessing the fecal microbiota of cats was established. The results showed that a large proportion of cats with CE had an altered fecal microbiota as evidenced by an increased DI. Prospective studies are warranted to evaluate the utility of this assay for clinical assessment of feline CE.

Untargeted metabolomic analysis in cats with naturally occurring inflammatory bowel disease and alimentary small cell lymphoma

Feline chronic enteropathy (CE) is a common gastrointestinal disorder in cats and mainly comprises inflammatory bowel disease (IBD) and small cell lymphoma (SCL). Differentiation between IBD and SCL can be diagnostically challenging. We characterized the fecal metabolome of 14 healthy cats and 22 cats with naturally occurring CE (11 cats with IBD and 11 cats with SCL). Principal component analysis and heat map analysis showed distinct clustering between cats with CE and healthy controls. Random forest classification revealed good group prediction for healthy cats and cats with CE, with an overall out-of-bag error rate of 16.7%. Univariate analysis indicated that levels of 84 compounds in cats with CE differed from those in healthy cats. Polyunsaturated fatty acids held discriminatory power in differentiating IBD from SCL. Metabolomic profiles of cats with CE resembled those in people with CE with significant alterations of metabolites related to tryptophan, arachidonic acid, and glutathione pathways.

Differentiating Inflammatory Bowel Disease from Alimentary Lymphoma in Cats: Does It Matter?

Differentiation of feline inflammatory bowel disease and intestinal small cell lymphoma can be challenging, and some clinicians argue that it is unnecessary because prognosis and treatment are similar. Differentiation of feline inflammatory bowel disease and intestinal small cell lymphoma can be challenging and some clinicians argue that it is unnecessary since prognosis and treatment are similar. Altough the body of research on this topic has increased over time, we still know little about etiopathogenesis, progression, alternative treatment modalities and prognosis of the different forms of FCE. While differentiating IBD from SCL might not alter a single patients' disease course, further research efforts are required to alter the disease course for our feline patient population as a whole.

Feline chronic enteropathy

Feline chronic enteropathy is a common disorder, especially in the senior cat population, with rising incidence over the past decade. Feline chronic enteropathy is considered an umbrella term comprising different diseases including food-responsive enteropathy, idiopathic inflammatory bowel disease and alimentary small cell lymphoma. However, differentiation between those diseases is often difficult in practice. This review will discuss the clinical approach to cats with chronic enteropathy, state-of-the-art diagnostic tests and pitfalls thereof as well as current therapeutic approaches. Although, much of the etiopathogenesis is still unknown, increased research efforts in this field have brought new insights into diagnostic and therapeutic options for these cats.

Characterization of the intestinal mucosal proteome in cats with inflammatory bowel disease and alimentary small cell lymphoma

BACKGROUND

Current tests for diagnosis and differentiation of lymphoplasmacytic enteritis (LPE) and small cell lymphoma (SCL) in cats are expensive, invasive, and lack specificity. The identification of less invasive, more reliable biomarkers would facilitate diagnosis.

OBJECTIVES

To characterize the mucosal proteome in endoscopically obtained, small intestinal tissue biopsy specimens. We hypothesized that differentially expressed proteins could be identified and serve as biomarker candidates for the differentiation of LPE and SCL in cats.

ANIMALS

Six healthy control cats, 6 cats with LPE, and 8 cats with SCL.

METHODS

The mucosal proteome was analyzed using 2-dimensional fluorescence difference gel electrophoresis (2D DIGE) and nanoflow liquid chromatography tandem mass spectrometry. For 5 proteins, results were verified by Western blot analysis.

RESULTS

A total of 2349 spots were identified, of which 9 were differentially expressed with a ≥2-fold change between healthy cats and cats with LPE and SCL (.01 < P < .001). Eight of these 9 spots were also differentially expressed between cats with LPE and cats with SCL (P .001 < P < .04). However, Western blot analysis for malate dehydrogenase-1, malate dehydrogenase-2, apolipoprotein, annexin IV, and annexin V did not confirm significant differential protein expression for any of the 5 proteins assessed.

CONCLUSIONS AND CLINICAL IMPORTANCE

Two-D DIGE did not identify potential biomarker candidates in the intestinal mucosa of cats with LPE and SCL. Future studies should focus on different techniques to identify biomarker candidates for cats with chronic enteropathies (CE).

Comprehensive comparison of upper and lower endoscopic small intestinal biopsy in cats with chronic enteropathy

Background

Integrating immunohistochemistry (IHC) and clonality testing with histopathology may improve the ability to differentiate inflammatory bowel disease (IBD) and alimentary small cell lymphoma (LSA) in cats.

Hypothesis/Objectives

To evaluate the utility of histopathology, IHC, and clonality testing to differentiate between IBD and LSA and agreement of diagnostic results for endoscopic biopsy (EB) samples from the upper (USI) and lower small intestine (LSI).

Animals

Fifty‐seven cats with IBD or LSA.

Methods

All cases were categorized as definitive IBD (DefIBD), possible LSA (PossLSA), probable LSA (ProbLSA), or definitive LSA (DefLSA) based on histopathology alone. Results from IHC and clonality testing were integrated.

Results

Based on histopathology alone, 24/57 (42.1%), 15/57 (26.3%), and 18/57 (31.6%) cats were diagnosed with DefIBD, PossLSA or ProbLSA, and DefLSA, respectively. After integrating IHC and clonality testing, 11/24 cases (45.8%) and 15/15 cases (100%) previously categorized as DefIBD and PossLSA or ProbLSA, respectively, were reclassified as LSA. A final diagnosis of IBD and LSA was reported in 13/57 (22.8%) and 44/57 (77.2%) cats, respectively. Agreement between USI and LSI samples was moderate based on histopathology alone (κ = 0.66) and after integrating IHC and clonality testing (κ = 0.70). However, only 1/44 (2.3%) of the LSA cases was diagnosed based on LSI biopsy alone.

Conclusions and Clinical Importance

Integrating IHC and clonality testing increased the number of cases diagnosed with LSA, but the consequence for patient outcome is unclear. There was moderate agreement between USI and LSI samples. Samples from the LSI rarely changed the diagnosis.

Multiple-Choice Questions in Small Animal Medicine: An Analysis of Cognitive Level and Structural Reliability, and the Impact of these Characteristics on Student Performance

Students entering the final year of the veterinary curriculum need to integrate information and problem solve. Assessments used to document competency prior to entry to the clinical environment should ideally provide a reliable measurement of these essential skills. In this study, five internal medicine specialists evaluated the cognitive grade (CG) and structural integrity of 100 multiple-choice questions (MCQs) used to assess learning by third-year students at a United States (US) veterinary school. Questions in CG 1 tested factual recall and simple understanding; those in CG 2 required interpretation and analysis; CG 3 MCQs tested problem solving. The majority (53%) of questions could be answered correctly using only recall or simple understanding (CG 1); 12% of MCQs required problem solving (CG 3). Less than half of the questions (43%) were structurally sound. Overall student performance for the 3 CGs differed significantly (92% for CG 1 vs. 84% for CG 3; p = .03. Structural integrity did not appear to impact overall performance, with a median pass rate of 90% for flawless questions versus 86% for those with poor structural integrity (p = .314). There was a moderate positive correlation between individual student outcomes for flawless CG 1 versus CG 3 questions (r_s = 0.471; p = < .001), although 13% of students failed to achieve an aggregate passing score (65%) on the CG 3 questions. These findings suggest that MCQ-based assessments may not adequately evaluate intended learning outcomes and that instructors may benefit from guidance and training for this issue.

Differentiation of lymphocytic-plasmacytic enteropathy and small cell lymphoma in cats using histology-guided mass spectrometry

BACKGROUND

Differentiation of lymphocytic-plasmacytic enteropathy (LPE) from small cell lymphoma (SCL) in cats can be challenging.

HYPOTHESIS/OBJECTIVE

Histology-guided mass spectrometry (HGMS) is a suitable method for the differentiation of LPE from SCL in cats.

ANIMALS

Forty-one cats with LPE and 52 cats with SCL.

METHODS

This is a retrospective clinicopathologic study. Duodenal tissue samples of 17 cats with LPE and 22 cats with SCL were subjected to HGMS, and the acquired data were used to develop a linear discriminate analysis (LDA) machine learning algorithm. The algorithm was subsequently validated using a separate set of 24 cats with LPE and 30 cats with SCL. Cases were classified as LPE or SCL based on a consensus by an expert panel consisting of 5-7 board-certified veterinary specialists. Histopathology, immunohistochemistry, and clonality testing were available for all cats. The panel consensus classification served as a reference for the calculation of test performance parameters.

RESULTS

Relative sensitivity, specificity, and accuracy of HGMS were 86.7% (95% confidence interval [CI]: 74.5%-98.8%), 91.7% (95% CI: 80.6%-100%), and 88.9% (95% CI: 80.5%-97.3%), respectively. Comparatively, the clonality testing had a sensitivity, specificity, and accuracy of 85.7% (95% CI: 72.8%-98.7%), 33.3% (95% CI: 14.5%-52.2%), and 61.5% (95% CI: 48.3%-74.8%) relative to the panel decision.

CONCLUSIONS AND CLINICAL IMPORTANCE

Histology-guided mass spectrometry was a reliable technique for the differentiation of LPE from SCL in duodenal formalin-fixed paraffin-embedded samples of cats and might have advantages over tests currently considered state of the art.

Characterization of the fecal microbiome in cats with inflammatory bowel disease or alimentary small cell lymphoma

Feline chronic enteropathy (CE) is a common gastrointestinal disorder in cats and mainly comprises inflammatory bowel disease (IBD) and small cell lymphoma (SCL). Both IBD and SCL in cats share features with chronic enteropathies such as IBD and monomorphic epitheliotropic intestinal T-cell lymphoma in humans. The aim of this study was to characterize the fecal microbiome of 38 healthy cats and 27 cats with CE (13 cats with IBD and 14 cats with SCL). Alpha diversity indices were significantly decreased in cats with CE (OTU p = 0.003, Shannon Index p = 0.008, Phylogenetic Diversity p = 0.019). ANOSIM showed a significant difference in bacterial communities, albeit with a small effect size (P = 0.023, R = 0.073). Univariate analysis and LEfSE showed a lower abundance of facultative anaerobic taxa of the phyla Firmicutes (families Ruminococcaceae and Turicibacteraceae), Actinobacteria (genus Bifidobacterium) and Bacteroidetes (i.a. Bacteroides plebeius) in cats with CE. The facultative anaerobic taxa Enterobacteriaceae and Streptococcaceae were increased in cats with CE. No significant difference between the microbiome of cats with IBD and those with SCL was found. Cats with CE showed patterns of dysbiosis similar to those in found people with IBD.

Results of histopathology, immunohistochemistry, and molecular clonality testing of small intestinal biopsy specimens from clinically healthy client-owned cats

Background

Histopathology, immunohistochemistry, and molecular clonality testing are metrics frequently used to diagnose chronic enteropathy (CE) in cats. However, normal values for these metrics have been based mainly on samples from cats that were relatively young, specific pathogen‐free, or both.

Objectives

To describe results of histopathology, immunohistochemistry, and clonality testing of endoscopically‐derived biopsy specimens of the upper small intestinal tract from a cohort of clinically healthy client‐owned cats.

Animals

Twenty clinically healthy client‐owned cats ≥3 years of age.

Methods

Tissue specimens were collected from the stomach and duodenum and evaluated single blinded by a board‐certified pathologist. In addition, samples were evaluated by routine immunohistochemistry and clonality testing. Cats were followed after the procedure for signs of CE.

Results

Integrated results from histopathology, immunohistochemistry, and clonality testing were interpreted as consistent with small cell lymphoma (SCL; n = 12), emerging SCL (n = 1), lymphocytic enteritis (n = 6), and pseudoclonality (n = 1). On follow‐up, 3 cats eventually developed clinical signs of CE, of which 2 were euthanized 295 and 654 days post‐endoscopy. The remaining 17 cats did not show clinical signs of CE after a median of 709 days (range, 219‐869 days).

Conclusions and Clinical Importance

Intestinal biopsy specimens from clinically healthy client‐owned cats commonly had abnormal findings on histopathology, immunohistochemistry, clonality testing, or some combination of these without apparent clinical relevance. Current diagnostic metrics for diagnosing CE in cats may need modification to be applicable to the general population of cats.

Leptin and ghrelin concentration in hyperthyroid cats before and after radioactive iodine therapy compared to euthyroid control cats

OBJECTIVE

Leptin and ghrelin, two peptide hormones with antagonistic effects on satiety and energy balance, could be involved in the pathogenesis of weight loss and polyphagia in cats with hyperthyroidism. Leptin generally decreases appetite and increases energy expenditure, while ghrelin exerts the opposite effects.

MATERIALS AND METHODS

Leptin and ghrelin were measured in 42 client owned hyperthyroid cats with a body condition score (BCS) ≤ 5/9 before (T0) and 4 weeks after radioactive iodine treatment (RAIT) (T1). Dependent on the serum total thyroxine concentration concentration at T1, cats were sub-classified as still hyperthyroid (ht-ht) (n = 4), euthyroid (ht-eu) (n = 10) or hypothyroid (ht-hypo) (n = 28). Results were compared to those of 22 healthy, euthyroid control cats with a comparable BCS (≤ 5/9) and age (≥ 8 years) to hyperthyroid cats.

RESULTS

At T0, there were no significant differences between hyperthyroid and control cats for leptin (p = 0.06) or ghrelin concentrations (p = 0.27). At T1, leptin significantly decreased in ht-hypo cats compared to T0 (p = 0.0008) despite a significantly increased body weight in this group (p = 0.0001). Serum ghrelin concentrations did not differ between hyperthyroid cats with a history of polyphagia compared to non-polyphagic cats (p = 0.42). After RAIT, ghrelin concentration significantly increased in all hyperthyroid cats (p < 0.0001), as well as in the subgroups ht-eu (p = 0.014) and ht-hypo (p < 0.0001) compared to their respective T0 baseline concentrations.

CONCLUSION

Leptin and ghrelin fluctuations may be indicative of changes in metabolic functions in cats with thyroid dysfunction. Leptin fluctuations occurred independently of body weight in different states of thyroid dysfunction; increasing ghrelin concentrations after RAIT suggest a ghrelin-independent mechanism for polyphagia in hyperthyroid cats.

Immunohistochemical and morphometric analysis of intestinal full-thickness biopsy samples from cats with lymphoplasmacytic inflammatory bowel disease

The distribution and numbers of CD3(+) T lymphocytes, immunoglobulin(+) plasma cells and calprotectin (L1)(+) macrophages was analyzed in full-thickness, formalin-fixed biopsy samples from the small intestine (duodenum, jejunum and ileum) and from the colon from nine cats with clinical signs of inflammatory bowel disease (IBD). All animals had lymphoplasmacytic enteritis or lymphoplasmacytic enterocolitis. Equivalent samples from the same intestinal regions from 12 healthy pet cats served as controls. Labelled cells in the lamina propria were counted by computer-aided morphometry. The different cell types were similarly distributed in both groups, but there were differences in their numbers. There were more CD3(+) T cells in the duodenum and jejunum of cats with IBD; however, the difference was only significant for the duodenum. There were significantly more IgA(+) cells in the duodenal crypt region. There were significantly more IgG(+) cells in the lower jejunal crypt region. Plasma cells expressing IgM were decreased in cats with IBD, but the difference was not significant. L1(+) macrophages were significantly decreased in the lower crypt area of the colon in cats with IBD and there was a trend to decreased L1(+) cells in the upper crypt area of the duodenum and jejunum. Comparison of the results of this study with previous findings on endoscopically-obtained duodenal biopsy samples from cats with IBD revealed some differences. These discrepancies might relate to differences between control cat populations, types of biopsy samples, methodological factors such as different counting techniques and the activity of the disease at the time of sampling.

The effects of a novel histamine-3 receptor inverse agonist on essential tremor in comparison to stable levels of alcohol

Essential tremor (ET) is a common movement disorder. Animal studies show that histaminergic modulation may affect the pathological processes involved in the generation of ET. Histamine-3 receptor inverse agonists (H3RIA) have demonstrated attenuating effects on ET in the harmaline rat model. In this double-blind, three-way cross-over, single-dose, double-dummy study the effects of 25 mg of a novel H3RIA (MK-0249) and a stable alcohol level (0.6 g L(-1)) were compared with placebo, in 18 patients with ET. Tremor was evaluated using laboratory tremorography, portable tremorography and a clinical rating scale. The Leeds Sleep Evaluation Questionnaire (LSEQ) and a choice reaction time (CRT) test were performed to evaluate potential effects on sleep and attention, respectively. A steady state of alcohol significantly diminished tremor as assessed by laboratory tremorography, portable tremorography and clinical ratings compared with placebo. A high single MK-0249 dose was not effective in reducing tremor, but caused significant effects on the LSEQ and the CRT test. These results suggest that treatment with a single dose of MK-0249 does not improve tremor in alcohol-responsive patients with ET, whereas stable levels of alcohol as a positive control reproduced the commonly reported tremor-diminishing effects of alcohol.

Numbers and distribution of immune cells in the tunica mucosa of the small and large intestine of full-thickness biopsies from healthy pet cats

In this study, CD3(+) T lymphocytes and IgA(+) , IgG(+) and IgM(+) plasma cells were quantified in the tunica mucosa of the intestinal tract of 12 pet cats without gastrointestinal diseases. The study included full-thickness biopsies of the duodenum, jejunum, ileum and colon. The distribution and quantification of CD3(+) T cells, IgA(+) , IgG(+) and IgM(+) plasma cells within the intestinal tunica mucosa was performed by using immunohistochemical methods and computer-aided morphometry. CD3(+) T cells were significantly prominent in the villi and their numbers increased from duodenum to ileum but decreased towards the colon. The predominant type of plasma cells was IgA(+) cells, followed by IgM(+) cells. The number of IgG(+) cells was generally low compared to the other plasma cell types investigated. The results of the vertical distribution showed that IgA(+) and IgM(+) plasma cells were most numerous in the lower crypt areas, whilst IgG(+) plasma cells accumulated in the upper crypt region with a decline towards the villi and the lower crypt areas of control cats. All types of plasma cells showed a general decline from the duodenum towards the caudal sections of the intestinal tract regarding the horizontal distribution of plasma cells. This study provides a comprehensive overview on the vertical and horizontal distribution and the number of CD3(+) T cells and IgA(+) , IgG(+) and IgM(+) plasma cells in the intestinal tunica mucosa of pet cats.

Phenotypical characterization, distribution and quantification of different mast cell subtypes in transmural biopsies from the gastrointestinal tract of cats with inflammatory bowel disease

In this study subtypes, distribution and number of mast cells were investigated within mucosa and submucosa of the gastrointestinal tract of 24 cats with inflammatory bowel disease (IBD) in comparison to 11 control cats. Paraffin sections of formalin-fixed transmural gastrointestinal biopsies from stomach, duodenum, jejunum, ileum and colon were examined. Mast cells were phenotyped and quantified based on their chymase and tryptase content, by applying a combined enzyme-histochemical and immunohistochemical double-labeling technique and on their heparin content by a metachromatic staining method (kresylecht-violet, MC(KEV)). Mast cells containing both chymase and tryptase were not found in any of the samples examined. Furthermore, in the stomach neither chymase (MC(C)) nor tryptase (MC(T)) bearing mast cells were detected. In cats with lymphocytic-plasmacytic enteritis or enterocolitis elevated numbers of MC(T) or MC(C) were identified in comparison to controls mainly located in the inflamed segments. The highest quantity of MC(C) was found in cats with eosinophilic gastroenterocolitis or enterocolitis in comparison to other IBD forms, but only minor numbers of MC(T) were detected in these cases. In cats with fibrosing enteropathy (FE) a decrease of MC(C) and mast cells containing heparin was detected in affected segments, while increased numbers of MC(T) were detected in all locations. The elevation in the number of MC(T) was higher in unaffected areas than in fibrotic regions. Regarding all IBD cases higher counts of MC(C) were found especially in the inflamed locations, whereas in unaffected segments increased numbers of MC(T) were detected. The clear predominance of MC(C) and MC(T) within the mucosa and of MC(KEV) within the submucosa of all cats examined possibly represents differences of the cytokine milieu within the intestinal layers. In FE, mast cells are possibly pivotal for the containment of the inflammatory process because of their antiinflammatory properties. The results of this study indicate that mast cells and their mediators are involved in the pathogenesis of different IBD forms in cats.

Chronic inflammatory and non-inflammatory diseases of the gastrointestinal tract in cats: Diagnostic advantages of full-thickness intestinal and extraintestinal biopsies

An evaluation of histological findings in full-thickness biopsies from the gastrointestinal tract (GIT) and extraintestinal samples of 43 cats with chronic GIT disease signs was performed. In the majority of cases (46.5%) inflammatory bowel disease, ie, lymphocytic-plasmacytic enteritis/colitis (32.6%), eosinophilic gastroenterocolitis (11.6%) and mixed inflammatory infiltration (2.3%), was diagnosed. Furthermore, in four animals non-inflammatory mucosal band-shaped fibrosis (9.3%), and in 10 cats (23.3%) a diffuse lymphoma, was found. Six cats displayed only a gastritis (7.0%) or lymphangiectasia (7.0%), respectively. In two cats a mast cell tumour (4.7%) was diagnosed. In one cat no histopathological lesions were found. The availability of transmural biopsies from all segments of the intestine and the collection of extraintestinal samples, especially mesenteric lymph nodes, is especially helpful for diagnosing intestinal tumours such as lymphomas and tumours of mast cell origin.