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.

Evaluation of Intestinal Barrier Dysfunction with Serum Iohexol Concentration in Dogs with Acute Hemorrhagic Diarrhea Syndrome.

Histopathologic examination of intestinal biopsies from dogs with acute hemorrhagic diarrhea syndrome (AHDS) reveals necrotizing enteritis and epithelial integrity loss. Serum iohexol measurement has been utilized to assess intestinal permeability. Our hypothesis is that dogs with AHDS have increased intestinal permeability, which is associated with the severity of clinical signs. In this prospective case-control study, 53 client-owned dogs (28 AHDS, 25 healthy controls) were evaluated. Clinical severity was assessed using the AHDS index and systemic inflammatory response syndrome (SIRS) criteria. Simultaneously, dogs received oral iohexol, and serum iohexol concentrations (SICs) were measured two hours later. Results indicated significantly higher (p = 0.002) SIC in AHDS dogs (median: 51 µg/mL; min-max: 9-246) than in healthy controls (30 µg/mL; 11-57). There was a significant positive correlation between AHDS index and SIC (rS = 0.4; p = 0.03) and a significant negative between SIC and serum albumin concentrations (Pearson r = -0.55; p = 0.01). Dogs with severe AHDS (mean 106 µg/mL; range: 17-246) demonstrated significantly higher (p = 0.002) SIC than those with mild to moderate disease (29 µg/mL; 9-54). These findings underscore the association between intestinal permeability and clinical severity in dogs with AHDS assessed by iohexol.

Reply to Piewbang et al. Domestic Cat Hepadnavirus Antigens in Lymphoma Tissues. Comment on "Beatty et al. Domestic Cat Hepadnavirus and Lymphoma. Viruses 2023, 15, 2294".

We are grateful to the authors for providing additional data to demonstrate the presence of domestic cat hepadnavirus in lymphoma tissues [...].

Domestic Cat Hepadnavirus and Lymphoma.

We write to comment on Piewbang C et al [...].

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.

Serum and Fecal 3-Bromotyrosine Concentrations in Dogs with Chronic Inflammatory Enteropathy: Clinical Parameters and Histopathological Changes.

Chronic inflammatory enteropathies (CIEs) in dogs involve the infiltration of gastrointestinal tissue with inflammatory cells. This study aimed to assess the sensitivity of serum and fecal 3-bromotyrosine (3-BrY) concentrations in dogs with CIE. The difference in 3-BrY concentrations in dogs with different gastrointestinal (GI) pathological changes was also assessed. In total, 68 dogs with CIE were enrolled in the study. The median serum 3-BrY concentration was 3.3 µmol/L, while the median 3-day mean and maximum fecal 3-BrY concentrations were 38.9 and 63.2 mmol/g of feces, respectively. The median serum C-reactive protein concentration was 45.0 mg/L. The median 3-day mean and maximum fecal α1-proteinase inhibitor concentrations were 6.1 and 9 µg/g of feces, respectively. Increased 3-BrY concentrations were observed in 90.9% of CIE dogs based on serum concentrations, 75.8% based on mean fecal concentrations, and 69.4% based on maximum fecal concentrations. A weak correlation (ρ = 0.31, p < 0.0118) was found between serum CRP and serum 3-BrY concentrations. There was no correlation between the canine chronic enteropathy clinical activity index and serum or fecal 3-BrY concentrations (p > 0.05). Additionally, no significant difference in serum or fecal 3-BrY concentrations was found among CIE dogs with different GI pathological changes (p > 0.05). In conclusion, dogs with CIE have increased 3-BrY concentrations in serum and fecal samples. However, 3-BrY concentrations may not accurately indicate the severity of gastrointestinal inflammation.

Correlation between Targeted qPCR Assays and Untargeted DNA Shotgun Metagenomic Sequencing for Assessing the Fecal Microbiota in Dogs.

DNA shotgun sequencing is an untargeted approach for identifying changes in relative abundances, while qPCR allows reproducible quantification of specific bacteria. The canine dysbiosis index (DI) assesses the canine fecal microbiota by using a mathematical algorithm based on qPCR results. We evaluated the correlation between qPCR and shotgun sequencing using fecal samples from 296 dogs with different clinical phenotypes. While significant correlations were found between qPCR and sequencing, certain taxa were only detectable by qPCR and not by sequencing. Based on sequencing, less than 2% of bacterial species (17/1190) were consistently present in all healthy dogs (n = 76). Dogs with an abnormal DI had lower alpha-diversity compared to dogs with normal DI. Increases in the DI correctly predicted the gradual shifts in microbiota observed by sequencing: minor changes (R = 0.19, DI < 0 with any targeted taxa outside the reference interval, RI), mild-moderate changes (R = 0.24, 0 < DI < 2), and significant dysbiosis (R = 0.54, 0.73, and 0.91 for DI > 2, DI > 5, and DI > 8, respectively), compared to dogs with a normal DI (DI < 0, all targets within the RI), as higher R-values indicated larger dissimilarities. In conclusion, the qPCR-based DI is an effective indicator of overall microbiota shifts observed by shotgun sequencing in dogs.

Prevalence of Clostridioides difficile in Canine Feces and Its Association with Intestinal Dysbiosis.

The role of Clostridioides (C.) difficile as an enteropathogen in dogs is controversial. In humans, intestinal bile acid-dysmetabolism is associated with C. difficile prevalence. The relationship between fecal qPCR-based dysbiosis index (DI) and especially the abundance of bile acid-converting Clostridium hiranonis with the presence of C. difficile in dogs was explored across the following 4 cohorts: 358 fecal samples submitted for routine diagnostic work-up, 33 dogs with chronic enteropathy, 14 dogs with acute diarrhea, and 116 healthy dogs. Dogs that tested positive for C. difficile had significantly higher DI (median, 4.4 (range from 0.4 to 8.6)) and lower C. hiranonis (median, 0.1 (range from 0.0 to 7.5) logDNA/g) than dogs that tested negative for C. difficile (median DI, -1 (range from -7.2 to 8.9); median C. hiranonis abundance, 6.2 (range from 0.1 to 7.5) logDNA/g; p < 0.0001, respectively). In 33 dogs with CE and 14 dogs with acute diarrhea, the treatment response did not differ between C. difficile-positive and -negative dogs. In the group of clinically healthy dogs, 9/116 tested positive for C. difficile, and 6/9 of these had also an abnormal DI. In conclusion, C. difficile is strongly linked to intestinal dysbiosis and lower C. hiranonis levels in dogs, but its presence does not necessitate targeted treatment.

Fecal acute phase proteins in cats with chronic enteropathies.

BACKGROUND: Chronic enteropathies (CE) are common in cats and reliable biomarkers that can distinguish different causes and predict or monitor response to treatment are currently lacking. HYPOTHESIS: To evaluate certain acute phase proteins in feces that could potentially be used as biomarkers in cats with CE. ANIMALS: Twenty-eight cats with either inflammatory bowel disease (IBD; n = 13), food-responsive enteropathy (FRE; n = 3) or small cell gastrointestinal lymphoma (SCGL; n = 12) and 29 healthy control cats were prospectively enrolled. METHODS: Fecal concentrations of haptoglobin, alpha-1-acid-glycoprotein (AGP), pancreatitis-associated protein-1 (PAP-1), ceruloplasmin, and C-reactive protein (CRP) were measured using Spatial Proximity Analyte Reagent Capture Luminescence (SPARCL) immunoassays before and after initiation of treatment. Cats were treated with diet and/or prednisolone (IBD cats), plus chlorambucil (SCGL cats). RESULTS: Compared with controls, median fecal AGP concentrations were significantly lower (25.1 vs 1.8 µg/g; P = .003) and median fecal haptoglobin (0.17 vs 0.5 µg/g), PAP-1 (0.04 vs 0.4 µg/g) and ceruloplasmin (0.15 vs 4.2 µg/g) concentrations were significantly higher (P < .001) in cats with CE. Median fecal AGP concentrations were significantly lower (P = .01) in cats with IBD and FRE (0.6 µg/g) compared with cats with SCGL (10.75 µg/g). A significant reduction was found in CE cats after treatment for median fecal ceruloplasmin concentrations (6.36 vs 1.16 µg/g; P = .04). CONCLUSIONS: Fecal AGP concentration shows promise to differentiate cats with SCGL from cats with IBD and FRE. Fecal ceruloplasmin concentrations may be useful to objectively monitor response to treatment in cats with CE.

Quantitative bioimaging of copper in frozen liver specimens from cats using laser ablation-inductively coupled plasma-mass spectrometry.

OBJECTIVES: The aim of this study was to assess laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) as a tool for measuring concentrations and determining accumulation of copper in frozen liver specimens from cats. METHODS: Six frozen liver specimens were evaluated by qualitative copper staining and quantitative flame atomic absorption spectroscopy. Tissue specimens were cryo-sectioned and quantitative bioimaging of copper was performed using LA-ICP-MS. Results were compared with those obtained using conventional methods. RESULTS: Of the six specimens, only one showed positive staining for copper with rhodanine. Using flame atomic absorption spectroscopy (FAAS), one specimen showed a deficient copper level (<100 µg/g dry weight), two specimens had copper within the reference interval (RI; 150-180 µg/g) and three specimens had copper concentrations above the RI. Bioimaging from LA-ICP-MS showed inhomogeneous distribution of hepatic copper. The areas with dense copper accumulation were represented as hotspots in the liver specimens. Hepatic copper quantification by LA-ICP-MS correlated well with copper quantified by FAAS (r = 0.96, P = 0.002). CONCLUSIONS AND RELEVANCE: Our findings suggest that quantitative bioimaging by LA-ICP-MS could be used to demonstrate the distribution and concentration of copper in frozen liver specimens from cats. The distribution of copper in these specimens was inhomogeneous with dense accumulation represented as hotspots on tissue sections. A positive correlation of hepatic copper concentrations determined by LA-ICP-MS and FAAS was found. Further studies to establish an RI for hepatic copper using this technique and to further determine its clinical utility are warranted.

Analytical validation of an ELISA for the measurement of feline pancreas-specific lipase and re-evaluation of the reference interval and decision threshold for diagnosing pancreatitis.

BACKGROUND: The diagnosis of feline pancreatitis can be challenging. The clinical presentation often includes mild, nonspecific clinical signs, such as vomiting, anorexia, and weight loss. Measurement of feline pancreatic lipase immunoreactivity (fPLI) concentration in serum has been reported to be sensitive and specific for a diagnosis of pancreatitis in cats. However, analytical validation for a widely available commercial assay for the measurement of fPLI concentration has not been published. OBJECTIVE: We aimed to analytically validate the Spec fPL assay (IDEXX Laboratories, Westbrook, ME), a commercial ELISA for the measurement of fPLI concentration, and re-evaluate its reference interval and decision threshold for diagnosing pancreatitis in cats. METHODS: Dilutional linearity, accuracy, precision, and the effect of interfering substances were assessed. The upper limit of the reference interval was calculated based on the 95th percentile of results from clinically healthy cats (n = 107), and a decision threshold for diagnosing pancreatitis was calculated with an expected specificity of 99%. RESULTS: Analytical validation demonstrated good linearity, accuracy, and precision, as well as the absence of interference from lipemia, hemolysis, or icterus. The upper limit of the reference interval for Spec fPL was determined to be 4.4 µg/L, and the decision threshold (a theoretical cut-off) for diagnosing pancreatitis was determined to be 8.8 µg/L based on a desired specificity of 99%. CONCLUSIONS: The Spec fPL assay is analytically valid, and results suggest that a decision threshold of 8.8 µg/L would have high diagnostic specificity for excluding clinically healthy cats.

Hip sensor location for flash interstitial glucose monitoring system provides adequate clinical accuracy in non-diabetic hypoglycemic dogs.

OBJECTIVE: Flash glucose monitoring systems (FGMS) are frequently used for interstitial glucose monitoring in dogs with diabetes mellitus and are typically placed between the scapulae. We aimed to evaluate the variability between glucose measurements from FGMS placed in 2 locations (between the scapulae and over the hip) in non-diabetic dogs during rapidly induced hypoglycemia. ANIMALS: 24 apparently healthy colony dogs that were subjects in a teaching laboratory. PROCEDURES: Prospective interventional study. FGMS sensors (FreeStyle Libre 14-day system) were placed between the scapulae and over the hip of all dogs. Regular insulin was administered (0.3 u/kg IV) and subsequent hypoglycemia was corrected. Before insulin administration and every 10 minutes over 90 minutes, interstitial glucose was recorded from both locations, and blood glucose was measured with a point-of-care blood glucose monitor (AlphaTRAK 2). RESULTS: There was a constant bias of 5.6 mg/dL (95% limits of agreement: -26.3 to 37.5 mg/dL) between locations, but the proportional bias was not apparent. There was a correlation between FGMS locations (r = 0.731, P = < .001). Sensor site B was clinically accurate with 100% of paired samples within Parkes error grid zones A (83%) and B (17%) but did not meet the criteria for analytical accuracy. CLINICAL RELEVANCE: In this model of induced hypoglycemia in healthy dogs, variation between measurements from FGMS locations was unlikely to have affected the clinical outcome. Placement of FGMS over the hip may be an acceptable alternative to placement between the scapulae, but the utility in hyperglycemic dogs is unknown.

Fecal S100A12 concentrations in cats with chronic enteropathies.

OBJECTIVES: The aim of this study was to compare fecal S100A12 concentrations in cats diagnosed with chronic enteropathy (CE) with healthy control cats. METHODS: This was a prospective, cross-sectional study. Forty-nine cats that had gastrointestinal signs for >3 weeks and a complete diagnostic work-up, including bloodwork, abdominal ultrasound and upper and/or lower gastrointestinal endoscopic biopsies, were enrolled into the CE group. Nineteen cats from the CE group were diagnosed with inflammatory bowel disease (IBD) or chronic inflammatory enteropathy (CIE) and 30 with alimentary lymphoma (LSA), based on histopathology results and additional testing with immunohistochemistry or molecular clonality testing with PCR if indicated. Nineteen apparently healthy control cats were included in the study. One fecal sample was collected from each cat and S100A12 concentrations were quantified by an analytically validated in-house ELISA. RESULTS: Fecal S100A12 concentrations differed between cats with LSA (median 110 ng/g; interquartile range [IQR] 18-548) and control cats (median 4 ng/g; IQR 2-25 [P <0.001]) and between cats with IBD (median 34 ng/g; IQR 15-973) and control cats (P <0.003). S100A12 concentrations in CE cats (median 94 ng/g; IQR 16-548) were statistically significantly higher compared with control cats (P <0.001). The area under the receiver operating characteristic curve (AUROC) to separate healthy cats from CE cats was 0.81 (95% confidence interval [CI] 0.70-0.92) and was statistically significant (P <0.001). The AUROC to separate cats with IBD from cats with LSA was 0.51 (95% CI 0.34-0.68) and was not statistically significant (P = 0.9). CONCLUSIONS AND RELEVANCE: Fecal S100A12 concentrations at the time of diagnostic investigation were higher in cats with CIE and LSA than in healthy controls but did not differ between cats with LSA and those with CIE/IBD. This study is an initial step toward evaluating a novel non-invasive marker of feline CIE. Further studies are needed to determine the diagnostic utility of fecal S100A12 concentrations in cats with CE, including comparing cats with IBD/CIE and LSA, and to compare them with cats with extra-gastrointestinal disease.

Urinary 15-F2t-Isoprostane Concentrations in Dogs with Liver Disease.

Isoprostanes are stable end products of lipid peroxidation that can be used as markers of oxidative stress. It was previously reported that a cohort of dogs with various liver diseases had increased urinary isoprostane concentrations compared to healthy control (HC) dogs. The aim of this study was to measure and report urinary isoprostane concentrations in dogs with different types of liver diseases. Urine was collected from 21 HC dogs and from 40 dogs with liver disease, including 25 with chronic hepatitis (CH), 7 with steroid hepatopathy (SH), and 8 with a congenital portosystemic shunt (CPSS). In this prospective, observational study, urinary 15-F2t-isoprostane (F2-IsoP) concentrations were measured by liquid chromatography/mass spectrometry and normalized to urinary creatinine concentrations. Concentrations were compared between groups using a Kruskal-Wallis test followed by Dunn's multiple comparisons tests. Significance was set at p < 0.05. The median (range) urinary F2-IsoP to creatinine ratios (ng/mg UCr) were 3.6 (2.2-12.4) for HC dogs, 5.7 (2.4-11.3) for dogs with CH, 4.8 (2.4-8.6) for dogs with SH, and 12.5 (2.9-22.9) for dogs with CPSS. CPSS dogs had significantly higher urinary F2-IsoP concentrations than HC dogs (p = 0.004), suggesting increased oxidative stress among this cohort.

Analytical Validation of an Assay for Concurrent Measurement of Amino Acids in Dog Serum and Comparison of Amino Acid Concentrations between Whole Blood, Plasma, and Serum from Dogs.

Amino acids play an important role in metabolism. Comprehensive analytical validation of an assay for the concurrent measurement of a large number of amino acids in dogs is lacking, which precludes its usefulness in a clinical setting. Amino acids are often measured in plasma or whole blood. However, serum is commonly used for gastrointestinal diagnostic testing in dogs and is therefore convenient to use. This study aimed to analytically validate an assay for the concurrent measurement of amino acids in dog serum and to evaluate differences in amino acid concentrations in whole blood, plasma, and serum in dogs. Analytical validation of the assay (Biochrom 30+ Amino Acid Analyzer) was performed on fresh or banked serum samples from dogs. Whole blood, plasma, and serum from 36 healthy dogs were analyzed, and concentrations of the three sample types were compared. The assay was demonstrated to be precise, reproducible, accurate, linear, and stable for the measurement of the majority of compounds detected in dog serum. Cystine, glutamic acid, and ethanolamine were shown to be unstable at conditions commonly encountered in clinical settings. Significant differences in concentrations were identified between whole blood, plasma, and serum for 33 of 42 compounds. Amino acid profiles in serum and plasma were more similar to each other than to those in whole blood. While some amino acids are present in similar concentrations in whole blood, plasma, and serum, others are highly dependent on the type of biofluid, and measurements warrant strict adherence to sample type-based reference intervals.

Serial Measurement of Serum Pancreatic Lipase Immunoreactivity, Feline Trypsin-like Immunoreactivity, and Cobalamin Concentrations in Kittens.

Serum concentrations of feline pancreatic lipase immunoreactivity (fPLI), feline trypsin-like immunoreactivity (fTLI), and cobalamin are commonly used for the diagnostic investigation of cats with gastrointestinal signs. No information on these parameters in healthy cats less than 1 year of age exists. We aimed to evaluate serum concentrations of fPLI, fTLI, and cobalamin in healthy cats at different time-points during their first 12 months of life. Fourteen healthy 2-month-old kittens were included. Blood was collected at 2, 3, 4, 6, and 12 months of age, and serum concentrations of fPLI, fTLI, and cobalamin were measured. While there was a statistically significant difference in serum fPLI concentrations over time, there was no statistically significant difference between individual time-points. There was no significant difference in serum fTLI concentrations over time. Serum cobalamin concentrations were below the reference interval in 3/13 cats at 2 months of age and were significantly lower by 3 months, when 13/14 had hypocobalaminemia. By 12 months, serum cobalamin had significantly increased, yet 4/12 cats still had hypocobalaminemia. Serum fPLI and fTLI concentrations did not show any statistically or clinically significant differences in young kittens. In contrast, serum cobalamin concentrations were commonly below the reference interval in kittens. Serum fPLI and fTLI concentrations are not practically affected by age in kittens as young as 2 months of age and could be used for the investigation of pancreatic diseases.

Effect of oral or injectable supplementation with cobalamin in dogs with hypocobalaminemia caused by chronic enteropathy or exocrine pancreatic insufficiency.

BACKGROUND: Recent studies have shown similar efficacy of oral supplementation of cobalamin compared to injectable supplementation in dogs, but few prospective, randomized studies have been published. OBJECTIVES: To evaluate efficacy of oral or injectable supplementation with cobalamin in normalizing serum cobalamin and methylmalonic acid (MMA) concentrations in dogs with hypocobalaminemia caused by either chronic enteropathy (CE) or exocrine pancreatic insufficiency (EPI). ANIMALS: Forty-six client owned dogs with hypocobalaminemia. METHODS: Prospective randomized clinical trial. Dogs were divided into 2 groups (CE or EPI), and randomized to receive oral or injectable supplementation of cobalamin. Each dog had 3 visits and serum cobalamin and MMA concentrations were measured at each visit. RESULTS: In dogs with CE, serum cobalamin concentrations increased with oral (P = .02; median 149 [range 149-231] to 733 [166-1467] ng/L, median difference 552 [95% CI: 181-899] ng/L) or injectable (P < .01; 168 [149-233] to 563 [234-965] ng/L, 367 [187-623] ng/L) supplementation. In dogs with EPI, serum cobalamin concentrations increased with oral (P = .01; 162 [149-214] to 919 [643-3863] ng/L, 705 [503-3356] ng/L) or injectable (P = .01; 177 [149-217] to 390 [243-907] ng/L, 192 [89-361] ng/L) supplementation. Serum MMA concentrations decreased with oral or injectable supplementation in dogs with CE, but only with oral supplementation in dogs with EPI. CONCLUSIONS AND CLINICAL IMPORTANCE: Oral supplementation is an alternative for cobalamin supplementation in dogs with hypocobalaminemia caused by CE or EPI.

Gastrointestinal transit time is faster in Beagle dogs compared to cats.

OBJECTIVE: To characterize gastrointestinal transit times (GITTs) and pH in dogs, and to compare to data recently described for cats. ANIMALS: 7 healthy, colony-housed Beagles. PROCEDURES: The GITTs and pH were measured using a continuous pH monitoring system. For the first period (prefeeding), food was withheld for 20 hours followed by pH capsule administration. Five hours after capsule administration, dogs were offered 75% of their historical daily caloric intake for 1 hour. For the second period (postfeeding), food was withheld for 24 hours. Dogs were allowed 1 hour to eat, followed by capsule administration. Both periods were repeated 3 times. The GITTs and pH were compared to published feline data. RESULTS: The mean ± SD transit times in dogs for the pre- and postfeeding periods, respectively, were esophageal, 3 ± 5 minutes and 13 ± 37 minutes; gastric, 31 ± 60 minutes and 829 ± 249 minutes; and intestinal, 795 ± 444 minutes and 830 ± 368 minutes. The mean ± SD gastrointestinal pH in dogs for the pre- and postfeeding periods, respectively, were esophageal, 6.6 ± 0.6 and 5.7 ± 1.0; gastric, 3.0 ± 1.4 and 1.8 ± 0.3; intestinal, 7.9 ± 0.3 and 7.7 ± 0.6; first-hour small intestinal, 7.6 ± 0.5 and 7.1 ± 0.4; and last-hour large intestinal, 7.9 ± 0.6 and 7.7 ± 1.0. The first-hour small intestinal pH and total transit times varied between dogs and cats depending on feed period (P = .002 and P = .04, respectively). Post hoc analysis revealed significantly shorter total transit times in dogs prefeeding (P = .005; mean ± SD for cats, 2,441 ± 1,359 minutes; for dogs, 828 ± 439 minutes) and postfeeding (P = .03; mean ± SD for cats, 3,009 ± 1,220 minutes; for dogs, 1,671 ± 513 minutes). Total transit time for dogs was also shorter pre- versus postfeeding (P = .003). CLINICAL RELEVANCE: GITT is faster in Beagles compared to cats, but gastrointestinal pH are similar when fed the same diet.

Detection of invasive Escherichia coli in dogs with granulomatous colitis using immunohistochemistry.

Granulomatous colitis in dogs can be associated with infection of the colonic mucosa by invasive strains of Escherichia coli. To date, fluorescence in situ hybridization (FISH) is the gold-standard method to assess intramucosal and intracellular bacterial invasion. However, FISH requires expensive fluorescence microscopy equipment and is therefore not widely available. We investigated the use of immunohistochemistry (IHC) as an alternative method to detect invasive E. coli in dogs with granulomatous colitis. Archived paraffin-embedded blocks were selected from 26 dogs with colitis, in which FISH had been performed by an outside laboratory. Using a polyclonal antibody, IHC for E. coli was performed on sections cut from the same blocks, and the presence of invasive E. coli was recorded. All 11 specimens in which FISH had detected E. coli were also positive on IHC, with strong immunolabeling in the cytoplasm of macrophages and extracellularly in the lamina propria; all 15 specimens that were negative for invasive bacteria on FISH were also negative on IHC. We found that IHC is a sensitive technique for the detection of invasive E. coli in dogs with granulomatous colitis.

Recovery of Fecal Microbiome and Bile Acids in Healthy Dogs after Tylosin Administration with and without Fecal Microbiota Transplantation.

Antibiotics cause gut dysbiosis and bile acid dysmetabolism in dogs. The effect of fecal microbiota transplantation (FMT) on microbiome and metabolome recovery is unknown. This prospective, randomized, placebo-controlled study included sixteen healthy purpose-bred dogs. All dogs received tylosin 20 mg/kg PO once daily (days 1-7) and were randomly assigned to either receive one FMT via enema (day 8), daily oral FMT capsules (days 8-21), or daily placebo capsules (days 8-21). Fecal samples were frozen at regular intervals until day 42. Quantitative PCR for 8 bacterial taxa was performed to calculate the fecal dysbiosis index (FDI) and fecal concentrations of unconjugated bile acids (UBA) were measured using gas chromatography-mass spectrometry. Tylosin altered the abundance of most evaluated bacteria and induced a significant decrease in secondary bile acid concentrations at day 7 in all dogs. However, most parameters returned to their baseline by day 14 in all dogs. In conclusion, tylosin markedly impacted fecal microbiota and bile acid concentrations, although return to baseline values was quick after the antibiotic was discontinued. Overall, FMT did not accelerate recovery of measured parameters. Further studies are warranted to confirm the value of FMT in accelerating microbiota recovery in antibiotic-associated dysbiosis in dogs.