Inflammatory bowel disease versus chronic enteropathy in dogs: are they one and the same?

Treatment response and long term follow up in nineteen dogs diagnosed with chronic enteropathy in Australia

Chronic enteropathy (CE) in dogs is common worldwide, but little data is available from Australia. The aim of this study was to describe treatment response and long-term outcome in a cohort of dogs with CE. Dogs were prospectively enrolled at Murdoch University and the University of Melbourne. After diagnostic investigation to rule out diseases other than CE, dogs underwent sequential therapeutic trials until achieving a clinical response (diet then antibiotics, and finally immunosuppressants). Success was defined as 75% reduction of clinical severity for a minimum of five weeks. A total of 21 dogs were enrolled, and 19 completed the study. One dog was euthanised for lack of response to treatment and one excluded for lack of owner compliance. Most dogs responded to diet (n = 10), followed by antibiotics (n = 7) and immunosuppressants (n = 2). Long-term remission (median 21.1 months, [3.0-44.7]) was achieved in eight out of ten dietary responders without additional treatment. In contrast, only two dogs with antibiotic response remained in long-term remission, of which one needed on-going antibiotic treatment. Longer term remission was achieved in the two dogs treated with immunosuppressants with on-going low dose therapy. This study concludes that most dogs referred for CE in Australia respond to dietary treatment (even after previous dietary interventions), and remission is long-term compared to dogs treated with an antibiotic. Furthermore, the need for long-term antibiotics in some dogs to maintain response may lead to antibiotic resistance. This study supports adequate dietary trials for CE in dogs, and a need for alternative second-line treatments.

Lymphatic endothelial cell immunohistochemical markers for evaluation of the intestinal lymphatic vasculature in dogs with chronic inflammatory enteropathy

Background

Lymphatic endothelial cell (LEC) immunohistochemical markers have identified intestinal lymphatic vasculature abnormalities in humans with inflammatory bowel disease, but have not been used to evaluate intestinal lymphatic vasculature in a group of dogs with chronic inflammatory enteropathy (CIE).

Objectives

To utilize LEC markers to identify and measure intestinal lymphatic vasculature in endoscopic biopsy samples of CIE dogs. To evaluate whether measured lymphatic vasculature variables correlate with serum albumin concentrations.

Animals

Twenty‐four dogs with CIE; n = 13, serum albumin concentration <2.5 g/dL (CIE‐protein‐losing enteropathy [PLE]), n = 11, serum albumin concentration ≥2.5 g/dL (CIE‐N).

Methods

Prospective study. Lymphatic endothelial cell immunolabeling with Prox‐1 and LYVE‐1 performed on endoscopic biopsy samples from 24 dogs with CIE. Duodenal and ileal villous lacteal width (VLW) and proprial mucosal lacteal width (MLW) were determined for each case and analyzed for correlation with serum albumin concentration. Lacteal dilatation scores using routine H&E histopathology were assessed for correlation with immunohistochemistry (IHC)‐calculated VLW and MLW.

Results

Lower serum albumin concentrations were correlated with increased VLW (rho = −.4644; P = .02) and MLW (rho = −.6514; P < .001) in the ileum. Lymphatic endothelial cell IHC identified presumptive proprial mucosal lymphangiectasia in some dogs that was not recognized with routine H&E staining. Lacteal dilatation scores were correlated with VLW in duodenum (rho = .4634; P = .02) and ileum (rho = .5292; P = .008), but did not correlate with MLW.

Conclusions and Clinical Importance

Lymphatic endothelial cell immunolabeling identified presumptive proprial mucosal lymphangiectasia in CIE dogs, particularly in the ileum of hypoalbuminemic dogs. Routine evaluation of villous lacteals likely underestimates abnormalities of the lymphatic vasculature in dogs with CIE.

Mucosal expression of S100A12 (calgranulin C) and S100A8/A9 (calprotectin) and correlation with serum and fecal concentrations in dogs with chronic inflammatory enteropathy

S100A12 and S100A8/A9 (calprotectin) are released from activated mononuclear cells and belong to the group of damage associated molecular patterns. Fecal S100A12 and S100A8/A9 concentrations have been suggested as biomarkers of intestinal inflammation in dogs with chronic inflammatory enteropathies (CIE). However, the mucosal cellular infiltrate in dogs with CIE is primarily lymphocytic-plasmacytic. Whether fecal S100A12 and S100A8/A9 levels reflect the number and/or activity of intestinal mucosal mononuclear cells, or whether these proteins are also produced by other cells has not been investigated. Thus, the aim of this study was to evaluate intestinal mucosal S100A12 and S100A8/A9 positivity and a potential relationship with the respective protein concentrations in serum and fecal samples in dogs with CIE. Serum (single sample), fecal samples (from 3 consecutive days), and gastrointestinal tissue biopsies (i.e., stomach, duodenum, ileum, and colon) were evaluated from 21 dogs with CIE. Serum and fecal S100A12 and S100A8/A9 concentrations were measured by analytically validated in-house ELISAs. Tissue biopsies underwent routine histopathology and immunohistochemical evaluation for S100A12 and S100A8/A9 positivity (S100A12⁺ and S100A8/A9⁺, each recorded as positive cells/mm²). S100A12⁺ and S100A8/A9⁺ cells were identified in all segments of the gastrointestinal tract, but were predominantly localized in the lamina propria (LP). Duodenal LP S100A12 positivity correlated statistically significantly with that in the stomach and ileum (ρ = 0.66 and 0.69, both p < 0.01), but was inversely correlated with the severity of macrophage infiltration in the duodenum (ρ=-0.47, p = 0.042). Ileal LP S100A8/A9 positivity correlated positively with the extent of ileal neutrophil and macrophage infiltration (ρ=0.61, p = 0.047). Fecal S100A12 concentrations strongly correlated with the number of S100A12⁺ cells along the entire gastrointestinal tract (ρ = 0.76, p = 0.028), whereas serum S100A12 concentrations were inversely correlated to colonic S100A12⁺ cell counts (ρ=-0.50, p = 0.043). Mucosal S100A8/A9⁺ cell counts were not associated with the corresponding fecal or serum S100A8/A9 concentrations. These results suggest that the intestinal mucosa in dogs with CIE contains an increased number of activated (pro-inflammatory) phagocytes expressing and secreting the S100A12 protein, but the macrophage population seen on routine histopathology is predominantly mature (anti-inflammatory) with a reduced or absent expression of S100A12 and a normal or increased expression of S100A8/A9. However, the distribution of intestinal S100A8/A9 expression requires further study.

Comparison of the systemic phospholipid profile in dogs diagnosed with idiopathic inflammatory bowel disease or food-responsive diarrhea before and after treatment

BACKGROUND

Inflammatory bowel disease (IBD) and food-responsive diarrhea (FRD) are common chronic enteropathies in dogs, of which the exact pathogenesis has not been fully understood. In people dyslipidemia has been reported in patients with IBD, and potential therapeutic benefits of polyunsaturated fatty acids (PUFA) in the treatment of IBD have been investigated. Studies on the phospholipid profile in dogs with IBD and FRD are still lacking.

AIM

To investigate the systemic phospholipid profile of dogs with IBD or FRD and to evaluate possible differences in phospholipids before and after treatment.

METHODS

The phospholipids in whole blood and EDTA plasma of 32 dogs diagnosed with either IBD (n = 16) or FRD (n = 16) were analyzed by hydrophilic interaction liquid chromatography (HILIC) prior to and after initiation of treatment, which included an elimination diet enriched with PUFAs.

RESULTS

A clear separation of the phospholipids between whole blood and plasma was demonstrated on principal component analysis plots. In addition to the type of specimen, treatment and disease severity were the most significant factors determining the variance of the phospholipid profile. An increase in lysolipids was observed after treatment. The phosphatidylcholine (PC) species changed from PC 38:4 before treatment to mainly lysophosphatidylcholine 18:0 after treatment. Furthermore, several differences in the abundance of individual phospholipids were identified between dogs with IBD and dogs with FRD and between treatment statuses using random forest analysis.

CONCLUSION

Significant variances were identified in the phospholipid profiles of dogs with IBD and FRD. These were particularly determined by type of specimen used, disease severity and treatment status. After treatment, a shift of phospholipid species towards lysophosphatidylcholine 18:0 was observed. Future studies should further investigate the role of lipids in the pathophysiology of IBD and FRD as well as their potential therapeutic benefits.

Platelet indices as biomarkers for characterization and determination of severity in canine chronic enteropathy

Human studies have shown an association between certain platelet indices and active inflammatory bowel disease when compared to healthy controls. The objectives of this retrospective study were to determine if any platelet indices differ between dogs with chronic enteropathies and healthy age- and sex-matched control dogs and are predictive of the severity of chronic enteropathy based on canine chronic enteropathy clinical activity index (CCECAI) scores. Medical records for 22 chronic enteropathy-positive dogs and 22 healthy control dogs were reviewed for historical and physical examination findings, platelet indices, and histologic diagnoses of chronic enteropathy. Platelet indices were compared between the groups, and an association between platelet indices and CCECAI scores in dogs with chronic enteropathy was investigated. Chronic diarrhea and weight loss were common clinical signs associated with chronic enteropathy. Lymphoplasmacytic enteritis was the most common histologic diagnosis. Only one platelet index, platelet component distribution width (P =  0.045), was found to be significantly different between the groups. For predicting severity of disease, determined by CCECAI score, statistically significant differences in indices associated with higher scores were platelet count (P = 0.024) and platelet dry mass distribution width (P =  0.036). Only platelet component distribution width showed potential in characterizing dogs with chronic enteropathy compared to normal dogs. Elevated platelet count and decreased platelet dry mass distribution width had a significant effect on total CCECAI scores. These findings suggest further investigation into the utility of platelet indices as predictors of disease presence and severity in dogs with chronic enteropathy is warranted.

Correlation between toll-like receptor 4 and nucleotide-binding oligomerization domain 2 (NOD2) and pathological severity in dogs with chronic gastrointestinal diseases

Toll-like receptor 4 (TLR4), nucleotide-binding oligomerization domain 2 (NOD2), and TNF-α play important roles in human inflammatory bowel diseases. The aim of this study was to elucidate the relationship between Toll-like receptor 4, NOD2, and TNF-α and the severity of chronic gastrointestinal diseases in dogs. We examined the expression levels of TLR4, NOD2, and TNF-α in the stomach, duodenum, ileum, colon, and rectum obtained from 21 dogs with chronic gastrointestinal disease, including inflammatory bowel disease, high-grade lymphoma, food responsive enteropathy, chronic pancreatitis, low-grade lymphoma, inflammatory colorectal polyp, and chronic colitis. Next, we demonstrated whether there is good correlation between the expression levels of TLR4, NOD2, and TNF-α and the histopathological analysis of each sample. We found that the level of TLR4 expression in the ileum of dogs with chronic gastrointestinal disease was positively associated with the histopathological severity. We also found that the level of NOD2 expression in the duodenum, stomach, and rectum was positively associated with the histopathological severity. However, there was no correlation between TNF-α expression in the 5 regions tested in this study and the histopathological severity. These findings indicate that TLR4 and NOD2 are remarkably associated with the severity of chronic gastrointestinal disease in dogs.

Narrative review of therapies for chronic enteropathies in dogs and cats

BACKGROUND

The optimal medical treatment for chronic enteropathy (CE) in dogs and cats is controversial. Sequential treatment using diet, antimicrobials, and immunosuppressive drugs is the most common strategy used by clinicians.

OBJECTIVES

To review the evidence for the effectiveness of dietary, drug, and alternative health interventions for inducing clinical remission in dogs and cats with CE.

ANIMALS

Retrospective study of dogs and cats with a diagnosis of chronic enteropathy.

METHODS

MEDLINE and Centre for Agriculture and Bioscience International (CABI) databases (1950 to March 2017) were searched for randomized controlled trials (RCTs), observational studies, and case series. The primary outcome was induction of clinical remission. All studies were evaluated using the quality of evidence grading guidelines (I-IV), which assign a score defining the strength and quality of the evidence.

RESULTS

Twenty-two studies (11 RCTs in dogs and 2 in cats and 9 cohort studies or case series) met the inclusion criteria for inducing remission of gastrointestinal (GI) signs. Of the 13 RCTs achieving grade I scores, 10 studies (totaling 218 dogs and 65 cats) compared single treatment: diet (n = 3), immunosuppressives (n = 3), antimicrobials (n = 2), anti-inflammatory drugs (n = 1), and probiotics (n = 1). Three case series (grade III) reported clinical remission using an elimination diet fed to 55 cats and use of enrofloxacin to induce remission in dogs with granulomatous colitis (2 studies totaling 16 dogs).

CONCLUSIONS AND CLINICAL IMPORTANCE

The current evidence for treatment of CE is much greater in dogs than in cats. There is sufficient strong evidence to recommend the use of therapeutic GI diets, glucocorticoids, enrofloxacin, or some combination of these in dogs with CE. Therapeutic GI diets and glucocorticoids are most useful in cats with CE.

Myenteric ganglionitis and intestinal leiomyositis in a Jack Russell terrier

A 9-year, 6-month old spayed female Jack Russell terrier presented with a 3-week history of intermittent vomiting, diarrhoea and weight loss. Serum biochemistry demonstrated severe panhypoproteinaemia, mild hypocalcaemia and mild hypocholesterolaemia, consistent with protein-losing enteropathy. Full-thickness biopsies obtained from the stomach and different sections of small intestine demonstrated histological features of both myenteric ganglionitis and early intestinal leiomyositis. Complete resolution of clinical signs occurred within 1 week of implementing immunosuppressive therapy. At the time of writing, 9 months following diagnosis, the dog remains in remission.

Comparison of intestinal expression of the apical sodium-dependent bile acid transporter between dogs with and without chronic inflammatory enteropathy

BACKGROUND

Intestinal absorption of bile acids is mediated by the apical sodium-dependent bile acid transporter (ASBT). Fecal bile acid dysmetabolism has been reported in dogs with chronic inflammatory enteropathy (CIE).

OBJECTIVE

Characterization of ASBT distribution along the intestinal tract of control dogs and comparison to dogs with CIE.

ANIMALS

Twenty-four dogs with CIE and 11 control dogs.

METHODS

The ASBT mRNA and protein expression were assessed using RNA in situ hybridization and immunohistochemistry, respectively. The concentrations of fecal bile acids were measured by gas chromatography-mass spectrometry. The fecal microbiota dysbiosis index was assessed with a quantitative polymerase chain reaction panel.

RESULTS

In control dogs, ASBT mRNA expression was observed in enterocytes in all analyzed intestinal segments, with highest expression in the ileum. The ASBT protein expression was restricted to enterocytes in the ileum, cecum, and colon. Dogs with CIE had significantly decreased expression of ASBT protein in the ileum (P = .001), which was negatively correlated with histopathological score (ρ = -0.40; Pcorr = .049). Additionally, dogs with CIE had a significantly increased percentage of primary bile acids in feces compared to controls (P = .04). The fecal dysbiosis index was significantly higher in dogs with CIE than in control dogs (P = .01).

CONCLUSIONS AND CLINICAL IMPORTANCE

These findings indicate that ileal protein expression of ASBT is downregulated in dogs with CIE. This change may be linked to the inflammatory process, intestinal dysbiosis, and fecal bile acid dysmetabolism observed in these patients.

Effect of an extruded animal protein-free diet on fecal microbiota of dogs with food-responsive enteropathy

Background

Dietary interventions are thought to modify gut microbial communities in healthy individuals. In dogs with chronic enteropathies, resolution of dysbiosis, along with remission of clinical signs, is expected with treatment.

Hypothesis/Objective

To evaluate changes in the fecal microbiota in dogs with food‐responsive chronic enteropathy (FRE) and in healthy control (HC) dogs before and after an elimination dietary trial with an animal protein‐free diet (APFD).

Animals

Dogs with FRE (n = 10) and HC (n = 14).

Methods

Dogs were fed the APFD for 60 days. Fecal microbiota was analyzed by Illumina 16S rRNA sequencing and quantitative polymerase chain reaction (PCR).

Results

A significantly lower bacterial alpha‐diversity was observed in dogs with FRE compared with HC dogs at baseline, and compared with FRE dogs after the trial. Distinct microbial communities were observed in dogs with FRE at baseline compared with HC dogs at baseline and compared with dogs with FRE after the trial. Microbial communities still were different in FRE dogs after the trial compared with HC dogs at baseline. In HC dogs, the fecal microbiota did not show a significant modification after administration of the APFD.

Conclusion and Clinical Importance

Our results suggest that, in FRE dogs, treatment with the APFD led to a partial recovery of the fecal microbiota by significantly increasing microbiota richness, which was significantly closer to a healthy microbiota after the treatment. In contrast, no changes were detected in the fecal microbiota of HC dogs fed the same APFD.

Changes in duodenal CD163-positive cells in dogs with chronic enteropathy after successful treatment

Chronic enteropathy (CE) in dogs is characterized retrospectively per treatment response as food-responsive enteropathy (FRE), antibiotic-responsive enteropathy (ARE), and immunosuppressant-responsive enteropathy (IRE) - the latter most resembling inflammatory bowel disease in people. The aim of this study was to characterize duodenal macrophages (Mϕ) in CE using immunohistochemistry; with calprotectin (CAL) as a marker of early differentiated Mϕ and CD163 expression as a marker for resident Mϕ in the duodenum before and after treatment. Prior to treatment, dogs with FRE and IRE had a lower CD163⁺/CAL⁺ ratio than control dogs (CTRL) in crypts; this increased significantly and normalized compared with CTRL after treatment. Conversely, the CD163⁺/CAL⁺ ratio in dogs with ARE was comparable to that in healthy dogs before and after treatment. In summary, these results suggest that Mϕ play a role in the pathogenesis of CE in FRE and IRE, with a decrease in resident Mϕ and an increase in early differentiated Mϕ, but not in ARE dogs. Mϕ normalize after successful treatment.

Clinical utility of currently available biomarkers in inflammatory enteropathies of dogs

Chronic inflammatory enteropathies (CIE) in dogs are a group of disorders that are characterized by chronic persistent or recurrent signs of gastrointestinal disease and histologic evidence of mucosal inflammation. These CIEs are classified as either food-responsive, antibiotic-responsive, or immunosuppressant-responsive enteropathy. Patients not clinically responding to immunomodulatory treatment are grouped as nonresponsive enteropathy and dogs with intestinal protein loss as protein-losing enteropathy. Disease-independent clinical scoring systems were established in dogs for assessment of clinical disease severity and patient monitoring during treatment. Histopathologic and routine clinicopathologic findings are usually not able to distinguish the subgroups of CIE. Treatment trials are often lengthy and further diagnostic tests are usually at least minimally invasive. Biomarkers that can aid in defining the presence of disease, site of origin, severity of the disease process, response to treatment, or a combination of these would be clinically useful in dogs with CIE. This article summarizes the following biomarkers that have been evaluated in dogs with CIE during the last decade, and critically evaluates their potential clinical utility in dogs with CIE: functional biomarkers (cobalamin, methylmalonic acid, folate, α1 -proteinase inhibitor, immunoglobulin A), biochemical biomarkers (C-reactive protein, perinuclear anti-neutrophilic cytoplasmic antibodies, 3-bromotyrosine, N-methylhistamine, calprotectin, S100A12, soluble receptor of advanced glycation end products, cytokines and chemokines, alkaline phosphatase), microbiomic biomarkers (microbiome changes, dysbiosis index), metabolomic biomarkers (serum metabolome), genetic biomarkers (genomic markers, gene expression changes), and cellular biomarkers (regulatory T cells). In addition, important performance criteria of diagnostic tests are briefly reviewed.

Characterization of the fecal virome in dogs with chronic enteropathy

The fecal virome has been investigated in humans and various animal species using next generation sequencing. However, limited information is available about the fecal virome of dogs with chronic enteropathy (CE). We aimed to characterize the canine fecal virome of dogs with CE and compare it with the virome of previously analyzed healthy dogs.A total of 16 adult dogs; 8 healthy dogs (data from a parallel study) and 8 dogs with CE had fecal samples assessed by viral shotgun sequencing. Fecal samples were subjected to enrichment of viral nucleic acids prior to sequencing and metagenomic analyses. Characterization of the complete genome of a canine kobuvirus was performed by Sanger sequencing. An additional 21 healthy dogs and 14 dogs with CE were further analyzed for the prevalence of canine kobuvirus.Three fecal samples from dogs with CE contained in total 3 eukaryotic viral families. In contrast, 4/8 fecal samples previously identified from healthy dogs, contained 5 eukaryotic viral families with 2 families exclusive to this group. Bacteriophages were identified in all fecal samples from CE and healthy dogs. Canine kobuvirus was identified in one dog with CE, by shotgun sequencing, and the complete genome was then characterized. This kobuvirus was classified within canine kobuvirus group, being similar to strains from Korea and China. The larger prevalence study did not detect additional samples positive for canine kobuvirus. The fecal virome of dogs with CE differs in number and type of viral families from healthy dogs. The first Australian canine kobuvirus sequence was identified and characterized from a dog with CE.

S100A12 concentrations and myeloperoxidase activities are increased in the intestinal mucosa of dogs with chronic enteropathies

Background

Intestinal mucosal S100A12 and myeloperoxidase (MPO) are inflammatory biomarkers in humans with inflammatory bowel disease (IBD). However, these biomarkers have not been studied in the intestinal mucosa of dogs with chronic enteropathies (CE), even though dogs with CE have increased S100A12 concentrations in feces and serum. This study investigated mucosal S100A12 concentrations and MPO activities in both dogs with CE and healthy Beagles. ELISA (S100A12 concentrations) and spectrophotometric methods (MPO activity) were used. The associations of both biomarkers with canine IBD activity index (CIBDAI), histopathologic findings, clinical outcome, and serum albumin concentrations were also investigated. We studied intestinal mucosal samples originating from different intestinal regions of 40 dogs with CE and 18 healthy Beagle dogs (duodenum, ileum, colon, and cecum).

Results

Compared with healthy Beagles, mucosal S100A12 concentrations in dogs with CE were significantly higher in the duodenum (p < 0.0001) and colon (p = 0.0011), but not in the ileum (p = 0.2725) and cecum (p = 0.2194). Mucosal MPO activity of dogs with CE was significantly higher in the duodenum (p < 0.0001), ileum (p = 0.0083), colon (p < 0.0001), and cecum (p = 0.0474). Mucosal S100A12 concentrations in the duodenum were significantly higher if the inflammatory infiltrate consisted mainly of neutrophils (p = 0.0439) or macrophages (p = 0.037). Mucosal S100A12 concentrations also showed a significant association with the severity of total histopathological injury and epithelial injury in the colon (p < 0.05). Mucosal MPO activity showed a significant association (p < 0.05) with the severity of total histopathological injury, epithelial injury, and eosinophil infiltration in the duodenum. There was no significant association of both biomarkers with CIBDAI or clinical outcome.

Conclusions

This study showed that both mucosal S100A12 concentrations and MPO activities are significantly increased in the duodenum and colon of dogs with CE; mucosal MPO was also increased in the ileum and cecum. Future research should focus on assessing the clinical utility of S100A12 and MPO as diagnostic markers in dogs with CE.

Identification of matrix metalloproteinase-2 and -9 activities within the intestinal mucosa of dogs with chronic enteropathies

BACKGROUND

Matrix metalloproteinases (MMPs) 2 and 9 are zinc- and calcium-dependent endopeptidases involved in the breakdown and reconstitution of extracellular matrix under both physiological and pathological conditions. Mucosal MMP-2 and -9 activities have been reported to be upregulated in the intestine of humans with inflammatory bowel disease (IBD), and in animal models of IBD. However, their involvement in the pathogenesis of canine chronic enteropathies (CE) is unknown. This study investigated mucosal pro- and active MMP-2 and -9 activities in dogs with CE and healthy dogs using gelatin zymography, and also to determine the association of their activities in dogs with CE with the canine IBD activity index (CIBDAI), histopathologic findings, the clinical outcome, and hypoalbuminemia. Intestinal mucosal samples from duodenum, ileum, colon, and cecum were collected from 40 dogs with CE and 18 healthy Beagle dogs.

RESULTS

In dogs with CE, the number of samples positive for mucosal pro- and active MMP-2 was significantly higher in the duodenum (P < 0.0001 and P = 0.011, respectively), ileum (P = 0.002 and P = 0.018, respectively), and colon (P < 0.0001 and P = 0.002, respectively), compared with healthy controls. Mucosal pro-MMP-9-positive samples in the duodenum and colon were significantly more frequent in dogs with CE than in healthy dogs (P = 0.0004 and P = 0.001, respectively). Despite the presence of mucosal samples positive for active MMP-9 in the intestinal segments of dogs with CE, the difference compared to healthy controls did not reach statistical significance. None of the intestinal mucosal samples in healthy dogs showed gelatinolytic activity corresponding to the control bands of active MMP-2 and -9. Mucosal active MMP-9 activities displayed a significant positive association with the severity of neutrophil infiltration in the duodenum (P = 00.040), eosinophils in the cecum (P = 00.037), and the CIBDAI score for ileum samples (P = 0.023). There was no significant association of pro- and active MMP-2 and -9 levels with the clinical outcome or hypoalbuminemia.

CONCLUSIONS

This study is the first to demonstrate upregulation of mucosal pro- and active MMP-2 and pro-MMP-9 in the intestine of dogs with CE compared to healthy dogs. The results provide supporting evidence for the possible involvement of MMP-2 and -9 in the pathogenesis of canine CE.

Association of fecal calprotectin concentrations with disease severity, response to treatment, and other biomarkers in dogs with chronic inflammatory enteropathies

BACKGROUND

Calprotectin is a marker of inflammation, but its clinical utility in dogs with chronic inflammatory enteropathies (CIE) is unknown.

OBJECTIVE

Evaluation of fecal calprotectin in dogs with biopsy-confirmed CIE.

ANIMALS

127 dogs.

METHODS

Prospective case-control study. Dogs were assigned a canine chronic enteropathy clinical activity index (CCECAI) score, and histologic lesions severity was assessed. Fecal calprotectin, fecal S100A12, and serum C-reactive protein (CRP) were measured. Food- or antibiotic-responsive cases (FRE/ARE, n = 13) were distinguished from steroid-/immunosuppressant-responsive or -refractory cases (SRE/IRE, n = 20). Clinical response to treatment in SRE/IRE dogs was classified as complete remission (CR), partial response (PR), or no response (NR).

RESULTS

Fecal calprotectin correlated with CCECAI (ρ = 0.27, P = .0065) and fecal S100A12 (ρ = 0.90, P < .0001), some inflammatory criteria, and cumulative inflammation scores, but not serum CRP (ρ = 0.16, P = .12). Dogs with SRE/IRE had higher fecal calprotectin concentrations (median: 2.0 μg/g) than FRE/ARE dogs (median: 1.4 μg/g), and within the SRE/IRE group, dogs with PR/NR had higher fecal calprotectin (median: 37.0 μg/g) than dogs with CR (median: 1.6 μg/g). However, both differences did not reach statistical significance (both P = .10). A fecal calprotectin ≥15.2 μg/g separated both groups with 80% sensitivity (95% confidence interval [95%CI]: 28%-100%) and 75% specificity (95%CI: 43%-95%).

CONCLUSIONS AND CLINICAL IMPORTANCE

Fecal calprotectin could be a useful surrogate marker of disease severity in dogs with CIE, but larger longitudinal studies are needed to evaluate its utility in predicting the response to treatment.

A dysbiosis index to assess microbial changes in fecal samples of dogs with chronic inflammatory enteropathy

Recent studies have identified various bacterial groups that are altered in dogs with chronic inflammatory enteropathies (CE) compared to healthy dogs. The study aim was to use quantitative PCR (qPCR) assays to confirm these findings in a larger number of dogs, and to build a mathematical algorithm to report these microbiota changes as a dysbiosis index (DI). Fecal DNA from 95 healthy dogs and 106 dogs with histologically confirmed CE was analyzed. Samples were grouped into a training set and a validation set. Various mathematical models and combination of qPCR assays were evaluated to find a model with highest discriminatory power. The final qPCR panel consisted of eight bacterial groups: total bacteria, Faecalibacterium, Turicibacter, Escherichia coli, Streptococcus, Blautia, Fusobacterium and Clostridium hiranonis. The qPCR-based DI was built based on the nearest centroid classifier, and reports the degree of dysbiosis in a single numerical value that measures the closeness in the l2 - norm of the test sample to the mean prototype of each class. A negative DI indicates normobiosis, whereas a positive DI indicates dysbiosis. For a threshold of 0, the DI based on the combined dataset achieved 74% sensitivity and 95% specificity to separate healthy and CE dogs.

The Microbiota Regulates Immunity and Immunologic Diseases in Dogs and Cats

The complex commensal microbiota found on body surfaces controls immune responses and the development of allergic and inflammatory diseases. New genetic technologies permit investigators to determine the composition of the complex microbial populations found on these surfaces. Changes in the microbiota (dysbiosis) as a result of antibiotic use, diet, or other factors thus influence the development of many diseases in the dog and cat. The most important of these include chronic gastrointestinal disease; respiratory allergies, such as asthma; skin diseases, especially atopic dermatitis; and some autoimmune diseases.

Evaluation of Serum 3-Bromotyrosine Concentrations in Dogs with Steroid-Responsive Diarrhea and Food-Responsive Diarrhea

Background

The clinical usefulness of serum 3‐BrY concentrations for subclassifying dogs with food‐responsive diarrhea (FRD) and steroid‐responsive diarrhea (SRD) has not been studied.

Hypothesis/Objectives

To compare serum 3‐BrY concentrations in dogs with FRD, dogs with SRD, and healthy control dogs.

Animals

38 dogs with FRD, 14 dogs with SRD, and 46 healthy dogs.

Methods

Prospective study. Measurement of 3‐BrY concentration in serum samples was performed by gas chromatography/mass spectrometry.

Results

There was no association of peripheral eosinophilia in dogs with FRD, SRD, and healthy control dogs (P = 0.069). There was no significant correlation between peripheral eosinophil counts and serum 3‐BrY concentrations (ρ = −0.15, P = 0.13). Serum 3‐BrY concentrations in dogs with SRD (median [range] = 3.27, 0.9–26.23 μmol/L) were significantly higher than in dogs with FRD (median [range] = 0.99, 0.62–8.82 μmol/L; P = 0.007) or in healthy dogs (median [range] = 0.62, 0.62–1.79 μmol/L; P < 0.001). Also, serum 3‐BrY concentrations in dogs with FRD were significantly higher than in healthy dogs (P = 0.025). There was no significant correlation between the canine chronic enteropathy clinical activity index and serum 3‐BrY concentrations (ρ = 0.17, P = 0.23).

Conclusions and Clinical Importance

Measurement of serum 3‐BrY concentrations, but not the peripheral eosinophil count, is helpful for detecting dogs with SRD and FRD.

Use of a Granulocyte Immunofluorescence Assay Designed for Humans for Detection of Antineutrophil Cytoplasmic Antibodies in Dogs with Chronic Enteropathies

BACKGROUND

Perinuclear antineutrophil cytoplasmic antibodies (pANCA) previously have been shown to be serum markers in dogs with chronic enteropathies, with dogs that have food-responsive disease (FRD) having higher frequencies of seropositivity than dogs with steroid-responsive disease (SRD). The indirect immunofluorescence (IIF) assay used in previous publications is time-consuming to perform, with low interobserver agreement.

HYPOTHESIS/OBJECTIVES

We hypothesized that a commercially available granulocyte IIF assay designed for humans could be used to detect perinuclear antineutrophil cytoplasmic antibodies in dogs.

ANIMALS

Forty-four dogs with FRD, 20 dogs with SRD, 20 control dogs, and 38 soft-coated wheaten terrier (SCWT) or SCWT-cross dogs.

METHODS

A granulocyte assay designed for humans was used to detect pANCA, cANCA, and antinuclear antibodies (ANA), as well as antibodies against proteinase-3 protein (PR-3) and myeloperoxidase protein (MPO) in archived serum samples.

RESULTS

Sensitivity of the granulocyte assay to predict FRD in dogs was 0.61 (95% confidence interval (CI), 0.45, 0.75), and specificity was 1.00 (95% CI, 0.91, 1.00). A significant association was identified between positive pANCA or cANCA result and diagnosis of FRD (P < 0.0001). Agreement between the two assays to detect ANCA in the same serum samples from SCWT with protein-losing enteropathy/protein-losing nephropathy (PLE/PLN) was substantial (kappa, 0.77; 95% CI, 0.53, 1.00). Eight ANCA-positive cases were positive for MPO or PR-3 antibodies.

CONCLUSIONS AND CLINICAL IMPORTANCE

The granulocyte immunofluorescence assay used in our pilot study was easy and quick to perform. Agreement with the previously published method was good.