Dogs as carriers of virulent and resistant genotypes of Clostridioides difficile

While previous research on zoonotic transmission of community-acquired Clostridioides difficile infection (CA-CDI) focused on food-producing animals, the present study aimed to investigate whether dogs are carriers of resistant and/or virulent C. difficile strains. Rectal swabs were collected from 323 dogs and 38 C. difficile isolates (11.8%) were obtained. Isolates were characterized by antimicrobial susceptibility testing, whole-genome sequencing (WGS) and a DNA hybridization assay. Multilocus sequence typing (MLST), core genome MLST (cgMLST) and screening for virulence and antimicrobial resistance genes were performed based on WGS. Minimum inhibitory concentrations for erythromycin, clindamycin, tetracycline, vancomycin and metronidazole were determined by E-test. Out of 38 C. difficile isolates, 28 (73.7%) carried genes for toxins. The majority of isolates belonged to MLST sequence types (STs) of clade I and one to clade V. Several isolates belonged to STs previously associated with human CA-CDI. However, cgMLST showed low genetic relatedness between the isolates of this study and C. difficile strains isolated from humans in Austria for which genome sequences were publicly available. Four isolates (10.5%) displayed resistance to three of the tested antimicrobial agents. Isolates exhibited resistance to erythromycin, clindamycin, tetracycline and metronidazole. These phenotypic resistances were supported by the presence of the resistance genes erm(B), cfr(C) and tet(M). All isolates were susceptible to vancomycin. Our results indicate that dogs may carry virulent and antimicrobial-resistant C. difficile strains.

Proposal for rational antibacterial use in the diagnosis and treatment of dogs with chronic diarrhoea

Chronic diarrhoea is a frequent complaint in canine practice and the diagnostic path is often characterised by numerous diagnostic tests and stepwise empirical treatments, often applied before gastrointestinal endoscopy/mucosal biopsies. These include dietary interventions (novel protein, hydrolysed protein diet), parasiticides and still, in many cases, antibacterials. Indiscriminate use of antibacterial drugs risks detrimental consequences for both the individual patient (antimicrobial resistance, long‐term disruption of intestinal bacterial populations, potential worsening of gastrointestinal signs) and the general public. For that reason, in this Perspective essay we advocate use of antibacterials only after histopathologic evaluation of gastrointestinal biopsies or, for those cases in which endoscopy is not possible, after other therapeutic trials, such as diet/pre‐probiotics or anti‐inflammatory drugs have proven unsuccessful. They should be reserved, after appropriate dietary trials, for those canine chronic diarrhoeic patients with signs of true primary infection (i.e. signs of systemic inflammatory response syndrome or evidence of adherent‐invasive bacteria) that justify antibacterial use.

Sensitivity and Specificity of Plasma ALT, ALP, and Bile Acids for Hepatitis in Labrador Retrievers

Background

Biochemical indicators for diagnosing liver disease are plasma alanine aminotransferase activity (ALT), alkaline phosphatase activity (ALP), and bile acid concentration (BA).

Objectives

To determine the sensitivity and specificity of ALT, ALP, and BA for detecting primary hepatitis (PH) in clinically healthy Labrador retrievers and investigate whether ALT and ALP can discriminate between dogs with PH and nonspecific reactive hepatitis (RH).

Animals

191 clinically healthy and 51 clinically ill Labrador retrievers with hepatic histopathology.

Methods

Retrospective study. Medical records were reviewed for ALT, ALP, preprandial BA, liver histopathology, and hepatic copper concentrations.

Results

In 64% (122/191) of the clinically healthy Labrador retrievers, hepatic histology revealed inflammatory infiltrates. This frequency might be biased because part of them was included as first‐line relatives of dogs with copper‐associated hepatitis. Sensitivity of ALT, ALP, and BA in this population for detecting acute hepatitis was 45, 15, and 15%, respectively. For chronic hepatitis, sensitivity was 71, 35, and 13%, respectively. Specificity of ALT, ALP, and BA was >90% for AH, CH, and RH. When increased liver enzymes were present, median ALT was significantly higher in PH cases (312 U/L, range 38–1,369) compared to RH cases (91 U/L, range 39–139) (P < .001). There was no difference in ALP between dogs with a PH and a RH (P = .361).

Conclusions and Clinical Importance

Histopathologic abnormalities in the liver were present in the majority of apparent clinically healthy Labrador retrievers. The sensitivity of ALT, ALP, and BA for detecting acute and chronic hepatitis in this population was low. More sensitive biomarkers are needed for early detection of liver disease in apparent clinically healthy dogs.

Use of Serum MicroRNAs as Biomarker for Hepatobiliary Diseases in Dogs

Background

Current biochemical indicators cannot discriminate between parenchymal, biliary, vascular, and neoplastic hepatobiliary diseases. MicroRNAs are promising new biomarkers for hepatobiliary disease in humans and dogs.

Objective

To measure serum concentrations of an established group of microRNAs in dogs and to investigate their concentrations in various types of hepatobiliary diseases.

Animals

Forty‐six client‐owned dogs with an established diagnosis of hepatobiliary disease and stored serum samples and eleven client‐owned healthy control Labrador Retrievers.

Methods

Retrospective study. Medical records of dogs with parenchymal, biliary, vascular, or neoplastic hepatobiliary diseases and control dogs were reviewed. Concentrations of miR‐21, miR‐122, miR‐126, miR‐148a, miR‐200c, and miR‐222 were quantified in serum by real‐time polymerase chain reaction.

Results

No different microRNA concentrations were found in the adenoma and congenital portosystemic shunt groups. In all other diseases, miR‐122 concentrations were elevated with the highest concentration in the mucocele group (267‐fold, CI: 40–1,768, P < .001). In dogs with biliary diseases, miR‐21 and miR‐222 were only increased in dogs with mucoceles (26‐fold, CI: 5–141, P = .005 and 13‐fold, CI: 2–70, P = .025, respectively). Uniquely increased microRNAs were found in the hepatocellular carcinoma group (miR‐200c, 35‐fold increase, CI: 3–382, P = .035) and the chronic hepatitis group (miR‐126, 22‐fold increase, CI: 5–91, P = .002).

Conclusions and Clinical Importance

A microRNA panel consisting of miR‐21, miR‐122, miR‐126, miR‐200c, and miR‐222 can distinguish between parenchymal, biliary, and neoplastic hepatobiliary diseases. Serum microRNA profiling is a promising new tool that might be a valuable addition to conventional diagnostics to help diagnose various hepatobiliary diseases in dogs.

Erythrocyte copper chaperone for superoxide dismutase and superoxide dismutase as biomarkers for hepatic copper concentrations in Labrador retrievers

Hereditary hepatic copper accumulation in Labrador retrievers leads to hepatitis with fibrosis and eventually cirrhosis. The development of a non-invasive blood-based biomarker for copper status in dogs could be helpful in identifying dogs at risk and to monitor copper concentrations during treatment. In this study, two cellular copper metabolism proteins, Cu/Zn superoxide dismutase (SOD1) and its chaperone (copper chaperone for SOD1, CCS) were measured in erythrocytes and tested for association with hepatic copper concentrations in 15 Labrador retrievers with normal or increased hepatic copper concentrations. Antibodies against CCS and SOD1 were applicable for use in canine specimens. This was demonstrated by the loss of immune-reactive bands for CCS and SOD1 in siRNA treated canine bile duct epithelial cells. Erythrocyte CCS and CCS/SOD1 ratios were decreased 2.37 (P <0.001) and 3.29 (P <0.001) fold in the high copper group compared to the normal copper group. Erythrocyte CCS and CCS/SOD1 ratio are potential new biomarkers for hepatic copper concentrations in Labrador retrievers and could facilitate early diagnosis and treatment monitoring for copper-associated hepatitis in dogs.

Gastric carcinoma in canines and humans, a review

Gastric carcinoma (GC) is the most common neoplasm in the stomach of dogs. Although incidence in the general population is reported to be low, breed-specific GC has a high incidence. Median age at presentation ranges from 8 to approximately 10 years. The disease is mostly located in the lesser curvature and antropyloric region of the stomach. Unfortunately, diagnosis is usually made when the disease is at an advanced stage and, therefore, prognosis is poor. Due to similarities in clinical presentation, diagnosis, histology and prognosis, canine GC may serve as a valuable model for human GC. Extensive pedigrees of canine gastric carcinoma cases could reveal insights for human gastric carcinoma. Putative species differences include the role of Helicobacter in pathogenesis, the wide array of genetic data and screening available for humans, and treatment protocols that are available for human GC.

Hepatocyte-derived microRNAs as sensitive serum biomarkers of hepatocellular injury in Labrador retrievers

Common parenchymal liver diseases in dogs include reactive hepatopathies and primary hepatitis (acute or chronic). In chronic hepatitis, there is usually a long subclinical phase. Specific clinical signs become overt only when liver damage is severe and in this phase, treatment is usually less effective. Limited data are available regarding the sensitivity of liver enzyme activity or biomarkers for early detection of subclinical hepatitis. Hepatocyte-derived microRNAs (HDmiRs) were recently identified as promising biomarkers for hepatocellular injury in multiple species. Here, the potential of the HDmiRs miR-122 and miR-148a as sensitive diagnostic biomarkers for hepatocellular injury in Labrador retrievers was investigated. Samples from 66 Labrador retrievers with histologically normal livers, high hepatic copper, and with various forms of liver injury were evaluated for serum alanine aminotransferase (ALT) activity and microRNA values. Median values of HDmiR-122 were 34.6 times higher in dogs with liver injury and high ALT than in normal dogs (95% confidence intervals [CI], 13-95; P <0.001). HDmiR-122 values were significantly increased in dogs with liver injury and normal ALT (4.2 times; 95% CI, 2-12; P <0.01) and in dogs with high hepatic copper concentrations and unremarkable histopathology (2.9 times; 95% CI, 1.1-8.0; P <0.05). Logistic regression analyses demonstrated that miR-122 and miR-148a were both predictors of hepatocellular injury. The sensitivity of miR-122 was 84% (95% CI, 73-93%), making it superior to ALT (55%; 95% CI, 41-68%) for the detection of hepatocellular injury in Labrador retrievers (P <0.001). This study demonstrated that serum HDmiR, particularly miR-122, is a highly sensitive marker for the detection of hepatocellular injury in Labrador retrievers and is a promising new biomarker that may be used for early detection of subclinical hepatitis in dogs.

Cyclooxygenase-2 and 5-lipoxygenase in dogs with chronic enteropathies

Background

Cyclooxygenase‐2 (COX‐2) is a key enzyme in the synthesis of pro‐inflammatory prostaglandins and 5‐lipoxygenase (5‐LO) is the major source of leukotrienes. Their role in IBD has been demonstrated in humans and animal models, but not in dogs with chronic enteropathies (CCE).

Hypothesis

COX‐2 and 5‐LO are upregulated in dogs with CCE.

Animals

Fifteen healthy control dogs (HCD), 10 dogs with inflammatory bowel disease (IBD), and 15 dogs with food‐responsive diarrhea (FRD).

Methods

Prospective study. mRNA expression of COX‐2, 5‐LO, IL‐1b, IL‐4, IL‐6, TNF, IL‐10 and TFG‐β was evaluated by quantitative real‐time RT‐PCR in duodenal and colonic biopsies before and after treatment.

Results

COX‐2 expression in the colon was significantly higher in IBD and FRD before and after treatment (all P < .01). IL‐1b was higher in FRD in the duodenum after treatment (P = .021). TGF‐β expression was significantly higher in the duodenum of HCD compared to FRD/IBD before treatment (both P < .001) and IBD after treatment (P = .012). There were no significant differences among groups and within groups before and after treatment for IL‐4, IL‐6, TNF, and IL‐10. There was a significant correlation between COX‐2 and IL‐1b in duodenum and colon before treatment in FRD and IBD, whereas 5‐LO correlated better with IL‐6 and TNF. IL‐10 and TGF‐β usually were correlated.

Conclusions and Clinical Importance

COX‐2 is upregulated in IBD and FRD, whereas IL‐1b and TGF‐β seem to be important pro‐ and anti‐inflammatory cytokines, respectively. The use of dual COX/5‐LO inhibitors could be an interesting alternative in the treatment of CCE.

[Doramectin intoxication in 3 kittens]

This case report describes 3 kittens with suspected doramectin toxicity. In a litter of 7 kittens treated with doramectin, 3 developed neurological symptoms. One kitten showed mild apathy and tremors, while a second one additionally presented behavioral changes and seizures that had to be treated with diazepam. Both kittens recovered completely. A third kitten was presented to us in coma 3 days following treatment with doramectin. Subsequently, this kitten developed behavioral changes such as aggression, hyperesthesia, tremors, and seizures and died 36 hours after presentation. Histopathologic examination of the brain showed cytotoxic edema and polioencephalomalacia. The doramectin dosage of the deceased kitten was 380 μg/kg.

Follow-up of 100 dogs with acute diarrhoea in a primary care practice

This study aimed to examine the aetiology of acute diarrhoea and the relapse rate in 100 client-owned dogs presented to a first-opinion clinic. History, physical examination, faecal testing and owner questionnaire data were collected at initial presentation (T0) and at either the time of relapse or at a recheck performed within 3 months. All dogs received treatment according to their clinical signs. Of 96 dogs that completed the study, 37 (38.5%) relapsed during the study period, 21 (21.9%) relapsed within 3 months, and 16 others (16.6%) at 3 months to 1 year after initial examination. Dogs that had undergone a change in housing location within 1 month prior to presentation and dogs <1 year old were significantly more likely to have positive parasitological analyses (P=0.02 and P=0.001, respectively). Pica was a risk factor for relapse (P=0.0002).

Polyunsaturated fatty acid-enriched diets used for the treatment of canine chronic enteropathies decrease the abundance of selected genes of cholesterol homeostasis

Lipids are important for cell function and survival, but abnormal concentrations may lead to various diseases. Cholesterol homeostasis is greatly dependent on the active transport by membrane proteins, whose activities coordinate lipid status with cellular function. Intestinal Niemann-Pick C1-Like 1 protein (NPC1L1) and scavenger receptor B1 (SR-B1) participate in the uptake of extracellular cholesterol, whereas ATP binding cassette A1 (ABCA1) mediates the efflux of excessive intracellular cholesterol. Caveolin-1 binds cholesterol and fatty acids (FA) and participates in cholesterol trafficking. Sterol response element binding protein-2 (SREBP-2) is a sensor that regulates intracellular cholesterol synthesis. Given that cholesterol is a constituent of chylomicrons, whose synthesis is enhanced with an increased FA supply, we tested the hypothesis that feeding polyunsaturated FA (PUFA)-enriched diets in treatment of canine chronic enteropathies alters the mRNA expression of genes involved in cholesterol homeostasis. Using quantitative reverse transcriptase polymerase chain reaction (RT-PCR), we compared the mRNA abundance of NPC1L1, SR-B1, ABCA1, caveolin-1, and SREBP-2 in duodenal mucosal biopsies of dogs with food-responsive diarrhea (FRD; n=14) and inflammatory bowel disease (IBD; n=7) before and after treatment with cholesterol-free PUFA-enriched diets and in healthy controls (n=14). The abundance of caveolin-1, ABCA1, and SREBP-2 were altered by PUFA-enriched diets (P<0.05), whereas that of NPC1L1 and SR-B1 mRNA remained unchanged. The gene expression of caveolin-1, ABCA1, and SREBP-2 was down-regulated (P<0.05) by PUFA-enriched diets in IBD dogs only. Our results suggest that feeding PUFA-enriched diets may alter cholesterol homeostasis in duodenal mucosal cells of dogs suffering from IBD.

Expression of Toll-like receptor 2 in duodenal biopsies from dogs with inflammatory bowel disease is associated with severity of disease

There is growing evidence that aberrant innate immune responses towards the bacterial flora of the gut play a role in the pathogenesis of canine inflammatory bowel disease (IBD). Toll-like receptors (TLR) play an important role as primary sensors of invading pathogens and have gained significant attention in human IBD as differential expression and polymorphisms of certain TLR have been shown to occur in ulcerative colitis (UC) and Crohn's disease (CD). The aim of the current study was to evaluate the expression of two TLR important for recognition of commensals in the gut. TLR2 and TLR4 mRNA expression in duodenal biopsies from dogs with IBD was measured and correlated with clinical and histological disease severity. Endoscopic duodenal biopsies from 20 clinical cases and 7 healthy control dogs were used to extract mRNA. TLR2 and TLR4 mRNA expression was assessed using quantitative real-time PCR. TLR2 mRNA expression was significantly increased in the IBD dogs compared to controls, whereas TLR4 mRNA expression was similar in IBD and control cases. In addition, TLR2 mRNA expression was mildly correlated with clinical severity of disease, however, there was no correlation between TLR2 expression and histological severity of disease.

Upregulation of toll-like receptors in chronic enteropathies in dogs

BACKGROUND

Inflammatory bowel disease (IBD) is thought to result from a dysregulated interaction between the host immune system and commensal microflora. Toll-like receptors (TLRs) recognize microbe-associated molecular patterns (MAMPs), but their role in enteropathies in dogs is unknown.

HYPOTHESIS

That there is a dysregulation of TLRs recognizing bacterial MAMPs in dogs with IBD.

ANIMALS

Sixteen healthy beagles and 12 dogs with steroid-treated (ST) and 23 dogs with food-responsive (FR) diarrhea.

METHODS

Prospective, observational study. mRNA expression of canine TLR2, 4, and 9 was evaluated by quantitative real-time RT-PCR in duodenal and colonic biopsies obtained before and after standard therapy. Samples from control dogs were taken at necropsy, with additional biopsies of stomach, jejunum, ileum, and mesenteric lymph node in 6 dogs.

RESULTS

There were significant differences (P< or = .017) in expression of TLR2, 4, and 9 between the 6 sampled locations in healthy control dogs (lymph node > small intestine > or = colon). Before therapy, ST expressed more mRNA than control dogs for all 3 receptors (P < .05). There were no significant differences between pretreatment and posttreatment values, even though 32/35 dogs improved clinically. No associations were found when comparing receptor mRNA expression with either histology or clinical activity scores.

CONCLUSIONS AND CLINICAL IMPORTANCE

Bacteria-responsive TLR2, 4, and 9 are upregulated in duodenal and colonic mucosa in IBD. This might lead to increased inflammation through interaction with the commensal flora. The absence of significant changes after therapy despite clinical improvement might point toward the existence of a genetic predisposition to IBD as described in human IBD.

Lymphocyte blastogenic response to ovalbumin in a model for canine allergy

Lymphocyte stimulation tests (LST) were performed in five dogs sensitised with ovalbumin (OVA) and seven healthy dogs. In addition, all five OVA-sensitised and two control dogs were tested after two in vivo provocations with OVA-containing eye drops. The isolated cells were suspended in culture media containing OVA and were cultured for up to 12 days. Proliferation was measured as reduction in 5,6-carboxylfluorescein diacetate succinimidyl ester (CFSE) intensity by flow cytometry on days 0, 3, 6, 9 and 12. A cell proliferation index (CPI) for each day and the area under the curve (AUC) of the CPI was calculated for each dog. All OVA-sensitised dogs demonstrated increased erythema after conjunctival OVA application. The presence of OVA-specific lymphocytes was demonstrated in 2/5 OVA-sensitised dogs before and 4/5 after in vivo provocation. Using the AUC, the difference between OVA-sensitised and control dogs was significant in all three LST before in vivo provocation (P<0.05) and borderline significant (P=0.053) in 2/3 LST after provocation. The most significant difference in CPI was observed after 9 days of culture (P=0.001). This pilot study indicates that the LST allows detection of rare antigen specific memory T-cells in dogs previously sensitised to, but not concurrently undergoing challenge by a specific antigen.

Empty sella syndrome, hyperadrenocorticism and megaoesophagus in a dachshund

A five-year-old, entire, male dachshund was presented with a five day history of hypersalivation and regurgitation as well as polyuria and polydipsia for several months. Chest radiographs demonstrated megaoesophagus and aspiration pneumonia. Furthermore, hyperadrenocorticism was demonstrated by means of elevations in levels of serum alkaline phosphatase and cholesterol, decreased urinary specific gravity, increased response to adrenocorticotropic hormone stimulation, insufficient suppression of the post-dexamethasone plasma cortisol levels, an increased endogenous adrenocorticotropic hormone concentration and bilaterally enlarged adrenal glands on abdominal ultrasound. The dog became severely dyspnoeic and was euthanased after magnetic resonance imaging was performed. The magnetic resonance imaging and necropsy revealed the sellar region mainly filled with fluid, with only small tissue remnants, a condition defined as empty sella syndrome in human medicine. To the author's knowledge, this is the first dog described with empty sella syndrome and only the second dog described with hyperadrenocorticism secondary to ectopic adrenocorticotropic hormone production. However, the association between empty sella syndrome and hyperadrenocorticism may be no more than incidental.