Differential effects of selective and non-selective cyclooxygenase inhibitors on fecal microbiota in adult horses

Clinical effects of a combination of phenylbutazone and omeprazole on chronic lameness in Mongolian horses

BACKGROUND

Phenylbutazone (PBZ) is the most commonly used drug to treat symptoms of lameness in horses; however, it is associated with adverse effects such as gastric ulcer syndrome (EGUS). Interestingly, many practitioners prescribe omeprazole (OME) concurrently with PBZ to prevent the development of EGUS. However, the efficacy and safety of this practice in Mongolian horses with chronic lameness remain unknown.

OBJECTIVES

To evaluate the clinical effects of a combination of PBZ and OME on chronic lameness in Mongolian horses.

STUDY DESIGN

Randomised block experimental design.

METHODS

Eighteen Mongolian horses with lameness score was ≥3 points, were divided into three treatment groups, with six horses in each group: placebo (CON), PBZ (4.4 mg/kg PO q. 24 h), or PBZ plus OME (4 mg/kg PO q. 24 h; PBZ + OME) in a randomised block design based on the initial lameness score. The horses were treated for 15 days. During this period, weekly gastroscopy, and physiological and biochemical tests were performed.

RESULTS

Both PBZ (median 1.0, interquartile range [IQR]: 0.8-1.3; p = 0.01) and PBZ + OME (median 1.0, IQR: 1.0-1.0; p = 0.01) significantly decreased the lameness score compared with before administration. In addition, PBZ significantly increased the equine glandular gastric disease (EGGD) score (3.0 ± 0.6, p < 0.001), GT-17 content (293.4 ± 21.8 pg/mL, p < 0.001), and pepsinogen-1 (PG1) content (295.3 ± 38.3 ng/mL, p < 0.001) compared with CON or PBZ + OME. However, it significantly reduced the total protein (53.6 ± 1.5 g/L, p < 0.05) and albumin (25.5 ± 1.8 g/L, p < 0.05) contents. Nevertheless, compared with PBZ, PBZ + OME significantly decreased the EGGD score (0.3 ± 0.5, p < 0.001) and significantly increased the gastric fluid pH (7.3 ± 0.5, p < 0.001), total protein content (62.5 ± 4.6 g/L, p = 0.009), and albumin content (29.4 ± 1.1 g/L, p = 0.004). Meanwhile, they significantly diminished the gastrin 17 (GT-17) (162.0 ± 21.0 pg/mL, p < 0.001) and PG1 (182.4 ± 22.5 ng/mL, p < 0.001) contents.

MAIN LIMITATIONS

Individual differences in horses were larger, but the sample size was small. There was larger interval between observations for each index.

CONCLUSIONS

Compared with PBZ alone, PBZ + OME had no therapeutic effect on chronic lameness; however, it reduced the occurrence of EGGD in Mongolian horses. Horses may be protected against chronic lameness and PBZ-induced EGGD by increasing the pH value, decreasing serum PG1 and GT-17 content, and preventing the reduction of myeloperoxidase content.

Integrated analysis of gut metabolome, microbiome, and exfoliome data in an equine model of intestinal injury

BACKGROUND

The equine gastrointestinal (GI) microbiome has been described in the context of various diseases. The observed changes, however, have not been linked to host function and therefore it remains unclear how specific changes in the microbiome alter cellular and molecular pathways within the GI tract. Further, non-invasive techniques to examine the host gene expression profile of the GI mucosa have been described in horses but not evaluated in response to interventions. Therefore, the objectives of our study were to (1) profile gene expression and metabolomic changes in an equine model of non-steroidal anti-inflammatory drug (NSAID)-induced intestinal inflammation and (2) apply computational data integration methods to examine host-microbiota interactions.

METHODS

Twenty horses were randomly assigned to 1 of 2 groups (n = 10): control (placebo paste) or NSAID (phenylbutazone 4.4 mg/kg orally once daily for 9 days). Fecal samples were collected on days 0 and 10 and analyzed with respect to microbiota (16S rDNA gene sequencing), metabolomic (untargeted metabolites), and host exfoliated cell transcriptomic (exfoliome) changes. Data were analyzed and integrated using a variety of computational techniques, and underlying regulatory mechanisms were inferred from features that were commonly identified by all computational approaches.

RESULTS

Phenylbutazone induced alterations in the microbiota, metabolome, and host transcriptome. Data integration identified correlation of specific bacterial genera with expression of several genes and metabolites that were linked to oxidative stress. Concomitant microbiota and metabolite changes resulted in the initiation of endoplasmic reticulum stress and unfolded protein response within the intestinal mucosa.

CONCLUSIONS

Results of integrative analysis identified an important role for oxidative stress, and subsequent cell signaling responses, in a large animal model of GI inflammation. The computational approaches for combining non-invasive platforms for unbiased assessment of host GI responses (e.g., exfoliomics) with metabolomic and microbiota changes have broad application for the field of gastroenterology. Video Abstract.

Current Understanding of Equine Gut Dysbiosis and Microbiota Manipulation Techniques: Comparison with Current Knowledge in Other Species

Understanding the importance of intestinal microbiota in horses and the factors influencing its composition have been the focus of many studies over the past few years. Factors such as age, diet, antibiotic administration, and geographic location can affect the gut microbiota. The intra- and inter-individual variability of fecal microbiota in horses complicates its interpretation and has hindered the establishment of a clear definition for dysbiosis. Although a definitive causal relationship between gut dysbiosis in horses and diseases has not been clearly identified, recent research suggests that dysbiosis may play a role in the pathogenesis of various conditions, such as colitis and asthma. Prebiotics, probiotics, and fecal microbiota transplantation to modulate the horse's gastrointestinal tract may eventually be considered a valuable tool for preventing or treating diseases, such as antibiotic-induced colitis. This article aims to summarize the current knowledge on the importance of intestinal microbiota in horses and factors influencing its composition, and also to review the published literature on methods for detecting dysbiosis while discussing the efficacy of gut microbiota manipulation in horses.

Updates on Diagnosis and Management of Colic in the Field and Criteria for Referral

Gastrointestinal colic is the most common primary care equine emergency and affects nearly one of four horses per year. Colic is a significant welfare concern for equine patients and a financial and emotional burden for owners. The primary care practitioner is instrumental in identifying critical cases quickly and making appropriate management recommendations to improve patient outcomes.

Multidose misoprostol pharmacokinetics and its effect on the fecal microbiome in healthy, adult horses

OBJECTIVE

To compare the pharmacokinetics between repeated doses and to characterize changes in the fecal microbiome after oral and rectal multidose misoprostol administration.

ANIMALS

6 healthy university-owned geldings.

PROCEDURES

In a randomized, crossover study, misoprostol (5 μg/kg) was administered orally or rectally every 8 hours for 10 doses, or not administered (control), with a 21-day washout between treatments. Concentration-versus-time data for dose 1 and dose 10 were subject to noncompartmental analysis. For microbiota analysis using 16S rRNA amplicon sequencing, manure was collected 7 days before study onset, immediately before dose 1, and 6 hours, 7 days, and 14 days after dose 10, with time-matched points in controls.

RESULTS

Repeated dosing-related differences in pharmacokinetic parameters were not detected for either administration route. The area under the concentration-versus-time curve was greater (P < .04) after oral versus rectal administration. The relative bioavailability of rectal administration was 4 to 86% of that of oral administration. Microbial composition, richness, and β-diversity differed among subjects (P < .001 all) while only composition differed between treatments (P ≤ .01). Richness was decreased 6 hours after dose 10 and at the control-matched time point (P = .0109) in all subjects. No other differences for time points, treatments, or their interactions were observed.

CLINICAL RELEVANCE

Differences in systemic exposure were associated with the route of administration but were not detected after repeated administration of misoprostol. Differences in microbiota parameters were primarily associated with interindividual variation and management rather than misoprostol administration.

Characterisation of faecal microbiota in horses medicated with oral doxycycline hyclate

BACKGROUND

Antimicrobial-associated diarrhoea is a common adverse effect of antimicrobial treatment in horses and has been reported following the administration of oral doxycycline. The administration of antimicrobials has also been associated with changes in the equine intestinal microbiota diversity yet has not been explored under doxycycline treatment.

OBJECTIVES

To describe the dynamics of the faecal microbial diversity following a 5-day oral administration of doxycycline in healthy horses with Streptococcus zooepidemicus infected tissue chambers.

STUDY DESIGN

Experimental prospective cohort study in a single horse group.

METHODS

Seven healthy adult horses with S. zooepidemicus infected tissue chambers received oral doxycycline at 10 mg/kg q 12 h for 5-days following the tissue chamber inoculation. Faeces were collected prior to the tissue chamber inoculation and until 28-days post inoculation. Faecal microbiota was characterised by high throughput sequencing of the V4 region of the 16S rRNA gene on the Illumina MiSeq sequencing platform. Bioinformatic analysis was performed with Mothur and statistical analysis were conducted on R Studio.

RESULTS

A significant decrease in alpha diversity, characterised by a decrease of richness and diversity, and a decrease in beta diversity, characterised by changes in relative abundance, occurred after initiation of and during the administration of doxycycline. A decrease in Verrucomicrobia and increase in Firmicutes:Bacteroidetes ratio occurred following the initiation of treatment, with a return to initial Firmicutes:Bacteroidetes ratio during the treatment. It took 23 days after discontinuing the treatment for the faecal microbiota to return close to the initial state.

MAIN LIMITATIONS

Lack of control population within the study.

CONCLUSIONS

Transitory intestinal dysbiosis occurs under oral administration of doxycycline in horses.

Interactions between NSAIDs, opioids and the gut microbiota - Future perspectives in the management of inflammation and pain

The composition of intestinal microbiota is influenced by a number of factors, including medications, which may have a substantial impact on host physiology. Nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics are among those widely used medications that have been shown to alter microbiota composition in both animals and humans. Although much effort has been devoted to identify microbiota signatures associated with these medications, much less is known about the underlying mechanisms. Mucosal inflammation, changes in intestinal motility, luminal pH and bile acid metabolism, or direct drug-induced inhibitory effect on bacterial growth are all potential contributors to NSAID- and opioid-induced dysbiosis, however, only a few studies have addressed directly these issues. In addition, there is a notable overlap between the microbiota signatures of these drugs and certain diseases in which they are used, such as spondyloarthritis (SpA), rheumatoid arthritis (RA) and neuropathic pain associated with type 2 diabetes (T2D). The aims of the present review are threefold. First, we aim to provide a comprehensive up-to-date summary on the bacterial alterations caused by NSAIDs and opioids. Second, we critically review the available data on the possible underlying mechanisms of dysbiosis. Third, we review the current knowledge on gut dysbiosis associated with SpA, RA and neuropathic pain in T2D, and highlight the similarities between them and those caused by NSAIDs and opioids. We posit that drug-induced dysbiosis may contribute to the persistence of these diseases, and may potentially limit the therapeutic effect of these medications by long-term use. In this context, we will review the available literature data on the effect of probiotic supplementation and fecal microbiota transplantation on the therapeutic efficacy of NSAIDs and opioids in these diseases.

Gut Microbiome Characteristics in feral and domesticated horses from different geographic locations

Domesticated horses live under different conditions compared with their extinct wild ancestors. While housed, medicated and kept on a restricted source of feed, the microbiota of domesticated horses is hypothesized to be altered. We assessed the fecal microbiome of 57 domestic and feral horses from different locations on three continents, observing geographical differences. A higher abundance of eukaryota (p < 0.05) and viruses (p < 0.05) and lower of archaea (p < 0.05) were found in feral animals when compared with domestic ones. The abundance of genes coding for microbe-produced enzymes involved in the metabolism of carbohydrates was significantly higher (p < 0.05) in feral animals regardless of the geographic origin. Differences in the fecal resistomes between both groups of animals were also noted. The domestic/captive horse microbiomes were enriched in genes conferring resistance to tetracycline, likely reflecting the use of this antibiotic in the management of these animals. Our data showed an impoverishment of the fecal microbiome in domestic horses with diet, antibiotic exposure and hygiene being likely drivers. The results offer a view of the intestinal microbiome of horses and the impact of domestication or captivity, which may uncover novel targets for modulating the microbiome of horses to enhance animal health and well-being.

Li Ang et al. present an investigation of feral and domesticated horse gut microbiomes across three continents. Their results provide new insight into how changes in horse lifestyle are reflected in the resident gut microbiome.

Non-steroidal anti-inflammatory drugs in equine orthopaedics

Orthopaedic disorders are commonly encountered in equine veterinary medicine, and non-steroidal anti-inflammatory drugs (NSAIDs) play an important role in the management of many equine orthopaedic disorders. There are multiple NSAIDs available for use in horses, including both non-selective and selective NSAIDS, and the body of literature evaluating the efficacy of these medications, their effects on normal and inflamed musculoskeletal tissues, and their side effects is broad. This review aims to summarise the current literature on the use of NSAIDs for equine orthopaedic disorders and examines new and future avenues for the management of inflammation in equine orthopaedics.

Use of Antibiotics in Equines and Their Effect on Metabolic Health and Cecal Microflora Activities

In the race against deadly diseases, multiple drugs have been developed as a treatment strategy in livestock. Each treatment is based on a specific mechanism to find a suitable drug. Antibiotics have become a fundamental part of the equine industry to treat bacterial diseases. These antibiotics have specific doses and side effects, and understanding each parameter allows veterinarians to avoid or limit the adverse effects of such drugs. Use of antibiotics causes microbial imbalance, decreased microbial diversity and richness in both cecal and fecal samples. Antibiotics reduced metabolites production such as amino acids, carbohydrates, lipids, and vitamins, increased multi-resistant microbes, and gives opportunity to pathogenic microbes such as Clostridium perfringens and Salmonella spp., to overgrow. Therefore, appropriate use of these antibiotics in equine therapy will reduce the adverse consequence of antibiotics on cecal microbiota activities.

The Fecal Bacterial Microbiota in Horses with Equine Recurrent Uveitis

The objective of this study was to describe and compare the fecal bacterial microbiota of horses with equine recurrent uveitis (ERU) and healthy horses using next-generation sequencing techniques. Fecal samples were collected from 15 client-owned horses previously diagnosed with ERU on complete ophthalmic examination. For each fecal sample obtained from a horse with ERU, a sample was collected from an environmentally matched healthy control with no evidence of ocular disease. The Illumina MiSeq sequencer was used for high-throughput sequencing of the V4 region of the 16S rRNA gene. The relative abundance of predominant taxa, and alpha and beta diversity indices were calculated and compared between groups. The phyla Firmicutes, Bacteroidetes, Verrucomicrobia, and Proteobacteria predominated in both ERU and control horses, accounting for greater than 60% of sequences. Based on linear discriminant analysis effect size (LEfSe), no taxa were found to be enriched in either group. No significant differences were observed in alpha and beta diversity indices between groups (p > 0.05 for all tests). Equine recurrent uveitis is not associated with alteration of the gastrointestinal bacterial microbiota when compared with healthy controls.

Effects of phenylbutazone alone or in combination with a nutritional therapeutic on gastric ulcers, intestinal permeability, and fecal microbiota in horses

Background

Gastrointestinal (GI) injury and dysbiosis are adverse events associated with nonsteroidal anti‐inflammatory drug (NSAID) use in horses. Phenylbutazone has been shown to alter GI barrier function both in vitro and ex vivo, but its effects on barrier function have not been assessed in vivo. In addition, the ability of nutritional therapeutics to prevent these changes is not known.

Objective

Our objectives were to determine whether (a) phenylbutazone affected barrier function in vivo and (b) if phenylbutazone‐induced GI injury could be ameliorated by the use of a nutritional therapeutic.

Animals

Thirty healthy horses were randomly assigned to 3 groups (n = 10 per group): control, phenylbutazone, or phenylbutazone plus nutritional therapeutic.

Methods

This study was conducted as a blinded, randomized block design. All horses were managed identically throughout the study period. Samples were collected throughout the study period to monitor fecal microbiota changes and gastric ulcers before and after treatment. Quantification of the bacterial 16S rRNA gene in blood was used as a marker of intestinal permeability.

Results

Phenylbutazone increased amounts of bacterial 16S rDNA in circulation 3.02‐fold (95% confidence interval [CI], 0.1.89‐4.17), increased gastric ulceration score by a mean of 1.1 grade (P = .02), and induced specific changes in the microbiota, including loss of Pseudobutyrivibrio of family Lachnospiraceae. These changes were attenuated by nutritional treatment.

Conclusions and Clinical Importance

Collectively, these findings suggest that phenylbutazone induces GI injury, including impaired barrier function, and that nutritional treatment could attenuate these changes.

Impact of concurrent treatment with omeprazole on phenylbutazone-induced equine gastric ulcer syndrome (EGUS)

BACKGROUND

Phenylbutazone is commonly prescribed for treatment of various painful or inflammatory disorders in horses, but is associated with gastrointestinal (GI) adverse effects. Anecdotally, many practitioners prescribe omeprazole concurrently with phenylbutazone to reduce development of equine gastric ulcer syndrome (EGUS), but the efficacy and safety of this practice remains unknown.

OBJECTIVES

To evaluate the effect of omeprazole on phenylbutazone-induced equine glandular gastric disease (EGGD) and equine squamous gastric disease (ESGD).

STUDY DESIGN

Randomised block experimental design.

METHODS

Twenty-two horses with EGGD and ESGD scores ≤2 were included. Horses were assigned to treatment groups: phenylbutazone (4.4 mg/kg PO q 12 h; PBZ), phenylbutazone plus omeprazole (4 mg/kg PO q. 24 h; PBZ/OME) or placebo (CON) in a randomised block design based upon initial EGGD score. Horses were treated for up to 14 days. Gastroscopy was performed weekly; CBC and biochemistry were performed at Day 0 and study end. Horses were monitored for signs of colic and/or diarrhoea.

RESULTS

EGGD score increased in PBZ (median change 1, inter-quartile range, [IQR], 0-2) compared to PBZ/OME (median change 0, IQR -1 to 0; P = .05). PBZ/OME (6/8) had more intestinal complications than CON (0/6; difference between proportions = 75%; 95% CI, 23%-93%; P = .03). Plasma protein concentrations decreased in PBZ, compared to CON (mean difference between groups, 14 g/L; 95% CI, 1.04-27; P = .03). Five horses were withdrawn from the study due to intestinal complications (n = 3 PBZ/OME and n = 2 PBZ); one horse (PBZ) was withdrawn due to severe grade 4 EGGD.

MAIN LIMITATIONS

Small sample size and changes in management for the 2-3 days prior to study initiation; variable treatment duration among groups due to development of complications.

CONCLUSIONS

Administration of omeprazole ameliorated PBZ-induced EGGD, but was associated with an increase in intestinal complications. Caution should be exercised when co-prescribing NSAIDs and omeprazole in horses, particularly in association with change in management.

Inhibition of cyclooxygenase-1 by nonsteroidal anti-inflammatory drugs demethylates MeR2 enhancer and promotes Mbnl1 transcription in myogenic cells

Muscleblind-like 1 (MBNL1) is a ubiquitously expressed RNA-binding protein, which is highly expressed in skeletal muscle. Abnormally expanded CUG-repeats in the DMPK gene cause myotonic dystrophy type 1 (DM1) by sequestration of MBNL1 to nuclear RNA foci and by upregulation of another RNA-binding protein, CUG-binding protein 1 (CUGBP1). We previously reported that a nonsteroidal anti-inflammatory drug (NSAID), phenylbutazone, upregulates MBNL1 expression in DM1 mouse model by demethylation of MeR2, an enhancer element in Mbnl1 intron 1. NSAIDs inhibit cyclooxygenase (COX), which is comprised of COX-1 and COX-2 isoforms. In this study, we screened 29 NSAIDs in C2C12 myoblasts, and found that 13 NSAIDs enhanced Mbnl1 expression, where COX-1-selective NSAIDs upregulated Mbnl1 more than COX-2-selective NSAIDs. Consistently, knockdown of COX-1, but not of COX-2, upregulated MBNL1 expression in C2C12 myoblasts and myotubes, as well as in myotubes differentiated from DM1 patient-derived induced pluripotent stem cells (iPSCs). Luciferase assay showed that COX-1-knockdown augmented the MeR2 enhancer activity. Furthermore, bisulfite sequencing analysis demonstrated that COX-1-knockdown suppressed methylation of MeR2. These results suggest that COX-1 inhibition upregulates Mbnl1 transcription through demethylation of the MeR2 enhancer. Taken together, our study provides new insights into the transcriptional regulation of Mbnl1 by the COX-1-mediated pathway.

Factors Influencing Equine Gut Microbiota: Current Knowledge

Gastrointestinal microbiota play a crucial role in nutrient digestion, maintaining animal health and welfare. Various factors may affect microbial balance often leading to disturbances that may result in debilitating conditions such as colic and laminitis. The invention of next-generation sequencing technologies and bioinformatics has provided valuable information on the effects of factors influencing equine gut microbiota. Among those factors are nutrition and management (e.g., diet, supplements, exercise), medical substances (e.g., antimicrobials, anthelmintics, anesthetics), animal-related factors (breed and age), various pathological conditions (colitis, diarrhea, colic, laminitis, equine gastric ulcer syndrome), as well as stress-related factors (transportation and weaning). The aim of this review is to assimilate current knowledge on equine microbiome studies, focusing on the effect of factors influencing equine gastrointestinal microbiota. Decrease in microbial diversity and richness leading to decrease in stability; decrease in Lachnospiraceae and Ruminococcaceae family members, which contribute to gut homeostasis; increase in Lactobacillus and Streptococcus; decrease in lactic acid utilizing bacteria; decrease in butyrate-producing bacteria that have anti-inflammatory properties may all be considered as a negative change in equine gut microbiota. Shifts in Firmicutes and Bacteroidetes have often been observed in the literature in response to certain treatments or when describing healthy and unhealthy animals; however, these shifts are inconsistent. It is time to move forward and use the knowledge now acquired to start manipulating the microbiota of horses.

A distinct gut microbiota composition in patients with ankylosing spondylitis is associated with increased levels of fecal calprotectin

Background

Ankylosing spondylitis (AS) shares many characteristics with inflammatory bowel disease (IBD). Intestinal microbiota most likely plays an important role in the development of IBDs and may also be involved in the pathogenesis of AS. We aimed to define and compare the fecal microbiota composition in patients with AS, ulcerative colitis (UC), and healthy controls (HC) and to determine relationships between fecal microbiota, fecal calprotectin, and disease-related variables in AS.

Methods

Fecal microbiota composition was assessed with GA-map™ Dysbiosis Test (Genetic Analysis, Oslo, Norway), which also reports the degree of deviation of the microbiota composition compared with a healthy control population, a Dysbiosis Index (DI) score 1–5. The AS patients were assessed with questionnaires, back mobility tests, fecal calprotectin, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).

Results

Totally, 150 patients with AS (55% men, median age 55.5 years, median BASDAI 3.2), 18 patients with UC (56% men, median age 30.5 years), and 17 HC (65% men, median age 22 years) were included. Principal component analysis showed highly separate clustering of fecal microbiota from the patients with AS, UC, and HC. Compared with HC, fecal microbiota in AS was characterized by a higher abundance of Proteobacteria, Enterobacteriaceae, Bacilli, Streptococcus species, and Actinobacteria, but lower abundance of Bacteroides and Lachnospiraceae.

Further, fecal microbiota composition differed between patients with normal (≤ 50 mg/kg, n = 57) and increased (≥ 200 mg/kg, n = 36) fecal calprotectin. Patients with increased fecal calprotectin had lower abundance of bacteria with anti-inflammatory properties such as Faecalibacterium prausnitzii and Clostridium and higher abundance of the genus Streptococcus. No association was found between the fecal microbiota composition and HLAB27 status, disease activity, function, or medication. Dysbiosis (defined as DI ≥ 3) was found in 87% of AS patients.

Conclusions

Patients with AS have a distinct fecal microbiota signature, which is linked to fecal calprotectin levels, a marker of intestinal inflammation, but not to other clinical parameters. These findings suggest a local interplay between intestinal microbiota and gut inflammation in AS.

Trial registration

ClinicalTrials.gov, NCT00858819. Registered March 9, 2009.

Culture-independent and dependent evaluation of the equine paranasal sinus microbiota in health and disease

BACKGROUND

Horses with bacterial sinusitis frequently undergo empirical treatment with antimicrobials, however, in some cases bacterial culture of the affected sinus is used to direct therapy. Data regarding which organisms are part of the commensal microbiota of the equine sinus are lacking making it difficult to interpret culture results and guide empiric antimicrobial selection.

OBJECTIVES

Our objectives were to describe the bacterial and fungal microbiota of the paranasal sinuses in clinically normal horses using culture-dependent and independent approaches and to compare the bacterial culture and susceptibility patterns of normal horses with those from horses affected with primary and secondary sinusitis.

STUDY DESIGN

Experimental study and descriptive retrospective review of case records.

METHODS

Sinus washes were collected from 23 healthy horses. Washes were submitted for routine culture and susceptibility testing and DNA was isolated for next generation sequencing of bacterial and fungal marker genes. For clinical cases of sinusitis, medical records from 2010 to 2017 were reviewed and horses diagnosed with primary and/or secondary sinusitis were included.

RESULTS

The paranasal sinus cavity hosts multiple bacterial and fungal organisms. The bacterial microbiota of healthy horses consists largely of uncultivable, aerobic bacteria. While few anaerobes were isolated from normal horses, the majority of clinical cases resulted in growth of anaerobic organisms with no difference in the proportion of aerobic and anaerobic bacteria isolated from clinical cases.

MAIN LIMITATIONS

Small sample size in both populations of horses and heterogeneity of the population prevent a more in-depth analysis.

CONCLUSIONS

The microbiota of the paranasal sinuses of horses consists primarily of aerobic bacteria and fungal organisms, the majority of which are uncultivable via common clinical methods. Anaerobic bacteria are found in the majority of horses with clinical sinusitis. These findings suggest anaerobic bacteria are associated with sinusitis and their presence should be considered when treating horses with sinusitis.

Comparison of the microbiome, metabolome, and lipidome of obese and non-obese horses

Metabolic diseases such as obesity and type 2 diabetes in humans have been linked to alterations in the gastrointestinal microbiota and metabolome. Knowledge of these associations has improved our understanding of the pathophysiology of these diseases and guided development of diagnostic biomarkers and therapeutic interventions. The cellular and molecular pathophysiology of equine metabolic syndrome (EMS) and obesity in horses, however, remain ill-defined. Thus, the objectives of this study were to characterize the fecal microbiome, fecal metabolome, and circulating lipidome in obese and non-obese horses. The fecal microbiota, fecal metabolome, and serum lipidome were evaluated in obese (case) horses (n = 20) and non-obese (control) horses (n = 20) matched by farm of origin (n = 7). Significant differences in metabolites of the mitochondrial tricarboxylic acid cycle and circulating free fatty acids were identified in the obese horses compared to the non-obese horses. These results indicate that the host and bacterial metabolism should be considered important in obese horses. Further studies to determine whether these associations are causal and the mechanistic basis of the association are warranted because they might reveal diagnostic biomarkers and therapeutic interventions to mitigate obesity, EMS, and sequelae including laminitis.

Lack of Small Intestinal Dysbiosis Following Long-Term Selective Inhibition of Cyclooxygenase-2 by Rofecoxib in the Rat

Intestinal dysbiosis is linked to numerous gastrointestinal disorders, including inflammatory bowel diseases. It is a question of debate if coxibs, selective inhibitors of cyclooxygenase (COX)-2, cause dysbiosis. Therefore, in the present study, we aimed to determine the effect of long-term (four weeks) selective inhibition of COX-2 on the small intestinal microbiota in the rat. In order to avoid mucosal damage due to topical effects and inflammation-driven microbial alterations, rofecoxib, a nonacidic compound, was used. The direct inhibitory effect of rofecoxib on the growth of bacteria was ruled out in vitro. The mucosa-sparing effect of rofecoxib was confirmed by macroscopic and histological analysis, as well as by measuring the intestinal levels of cytokines and tight junction proteins. Deep sequencing of bacterial 16S rRNA revealed that chronic rofecoxib treatment had no significant influence on the composition and diversity of jejunal microbiota. In conclusion, this is the first demonstration that long-term selective inhibition of COX-2 by rofecoxib does not cause small intestinal dysbiosis in rats. Moreover, inhibition of COX-2 activity is not likely to be responsible per se for microbial alterations caused by some coxibs, but other drug-specific properties may contribute to it.

Identification of modifiable factors associated with owner-reported equine laminitis in Britain using a web-based cohort study approach

Background

Equine laminitis is a complex disease that manifests as pain and lameness in the feet, often with debilitating consequences. There is a paucity of data that accounts for the multifactorial nature of laminitis and considers time-varying covariates that may be associated with disease development; particularly those that are modifiable and present potential interventions. A previous case-control study identified a number of novel, modifiable factors associated with laminitis which warranted further investigation and corroboration. The aim of this study was to identify factors associated with equine laminitis in horses/ponies in Great Britain (GB) using a prospective, web-based cohort study design, with particular interest in evaluating modifiable factors previously identified in the case-control study.

Results

Self-selected horse/pony owners in GB submitted initial baseline and follow-up health and management questionnaires for 1070 horses/ponies between August 2014 and December 2016. The enrolled horses/ponies contributed 1068 horse-years at risk with a median of 38 days between questionnaire submissions. Owners reported 123 owner-recognised and/or veterinary-diagnosed episodes of active laminitis using a previously-validated laminitis reporting form. Multivariable Cox regression modelling identified 16 risk/protective factors associated with laminitis development. In keeping with the previous case-control study, a prior history of laminitis (particularly non-veterinary-diagnosed episodes), soreness after shoeing/trimming and weight gain were associated with higher rates of laminitis. There is now strong evidence that these risk factors should be used to guide future recommendations in disease prevention. Factors with some prior evidence of association included breed, steroidal anti-inflammatory administration, transport and worming. The modifiable factors amongst these should be the focus of future laminitis studies. The remainder of the identified factors relating to health, turnout and grazing management and feeding are novel, and require further investigation to explore their relationship with laminitis and their applicability as potential interventions.

Conclusions

This study has demonstrated a temporal relationship between a number of horse- and management-level factors and laminitis, identifying potential interventions and important risk groups for which these interventions would be of particular importance. These results serve as a sound evidence-base towards the development of strategic recommendations for the horse/pony-owning population to reduce the rate of laminitis in GB.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-1798-8) contains supplementary material, which is available to authorized users.