How Can Nutrition Help with Gastrointestinal Tract-Based Issues?

Many horses are fed differently than their wild ancestors. They often have limited access to pasture and are fed conserved forage and concentrates rich in starch and sugars, in only 2 meals per day. Feeding practices in contrast to natural feeding behavior can lead to gastrointestinal issues. Standard nutritional evaluation is warranted because of its important role in prevention and in treatment and management of diseases. When medical and nutritional treatments are combined, success rates are higher. New techniques to characterize equine microbiota have been used, allowing for microbiota manipulation to prevent and treat intestinal diseases.

DESCRIPTION OF GASTRIC ULCERS AND OF THEIR SUSPECTED, ASSOCIATED RISK FACTORS IN DECEASED WILD EQUIDS AT THE RÉSERVE AFRICAINE DE SIGEAN, FRANCE (2010-2016).

Gastric ulcers are common in domestic horses and foals, affecting at least 90% of unmedicated racehorses in active training. Despite these high prevalences in domestic horses, literature about this condition in wild equids is almost nonexistent. The presence of gastric ulcers was evaluated at necropsy in six species of wild equids that died at the Réserve Africane de Sigean, a safari park in the south of France from 2010 to 2016. Among the 55 individuals that died during that period, a description of the gastric mucosa was available in 82% (45/55) of cases. Considering the cases for which a description of the gastric mucosa was available, the prevalence of gastric ulcers was 64% (29/45). The highest prevalences were noted in Grant's zebra (Equus quagga boehmi) and Hartmann's mountain zebra (Equus zebra hartmannae) at 83% and 100%, respectively. In contrast to what is reported in domestic foals, gastric ulcerations were only diagnosed in one foal (out of 11 foals necropsied). The higher prevalence was noted in young individuals (3-36 mo old) at 93% (14/15); the lesions observed consisted mainly of single to multiple, superficial lesions, of which, only the mucosa was missing; these superficial lesions are often considered not clinically significant. The prevalence was lower for adults (74%; 14/19), but lesions were deeper or with a hyperemic or inflammatory appearance. All the lesions observed were located in the gastric, nonglandular, stratified squamous mucosa, along the margo plicatus. No statistical correlation could be found between the development of gastric ulcers and an ongoing, chronic pathologic process or a digestive tract pathology. The detection of gastric ulcers was, therefore, significantly greater in wild equids isolated in smaller enclosures. Nevertheless, additional larger-scale research is needed to point out predisposing factors in equids under human care.

Changes in saliva analytes in equine gastric ulcer syndrome (EGUS) after treatment: a pilot study.

Equine gastric ulcer syndrome (EGUS) is a prevalent condition in horses, affecting up to 93% of racehorses. Comprising the equine squamous gastric disease (ESGD) and the equine glandular gastric disease (EGGD), EGUS poses significant health challenges. Saliva, a non-invasive and easily obtainable sample, is increasingly recognized for its potential as a source of biomarkers in horses. This study investigates changes in saliva analytes using automated assays before and after EGUS treatment, aiming to identify biomarkers indicative of treatment success or failure. A total of 28 horses diagnosed with EGUS were treatment with omeprazole for six weeks and further divided into successful (n = 15) or unsuccessful (n = 13) treatment group. Saliva samples were collected before and after treatment, and analytes related to enzymes, metabolites, proteins, redox biomarkers, and minerals were measured using an automated chemistry analyzer. Results revealed that horses with successful treatment, indicated by reduced EGGD and ESGD scores, showed significant increases in bicarbonate and urea, and decreases in adenosine deaminase (ADA), and creatine kinase (CK). Conversely, horses with non-successful treatment showed no significant changes in salivary analytes. These analytes have the advantages of an easy and fast measurement and the possibility of being applied in routine. Further studies with larger populations should be performed to establish the possible practical application of these analytes as biomarkers of treatment.

Measurement of Trace Elements (Zinc, Copper, Magnesium, and Iron) in the Saliva of Horses: Validation Data and Changes in Equine Gastric Ulcer Syndrome (EGUS).

The objective of this study was to evaluate the possible use of spectrophotometric assays for the measurement of trace elements, including Zinc (Zn), Copper (Cu), Magnesium (Mg), and iron (Fe) in the saliva of horses and study their possible changes in equine gastric ulcer syndrome (EGUS). EGUS is a highly prevalent disease, with a current high incidence due to the increase in intensive management conditions. There are two EGUS diseases: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD), which can appear individually or together. For this purpose, automated spectrophotometric assays for measuring these analytes in horse saliva were analytically validated. Then, these analytes were measured in the saliva of horses with only ESGD, only EGGD, both ESGD and EGGD and a group of healthy horses. The methods used to measure the analytes were precise and accurate. Horses diagnosed with EGGD presented significantly lower levels of Zn and Mg. Fe concentrations were significantly lower in the saliva of horses with ESGD and EGGD. Overall, these results indicate that there are changes in trace elements in saliva in EGUS that could reflect the physiopathological mechanisms involved in this process and open the possibility of using trace elements as biomarkers of this syndrome.

Changes in the saliva proteome analysed by gel-proteomics in horses diagnosed with equine gastric ulcer syndrome (EGUS) at diagnosis and after successful treatment.

Equine gastric ulcer syndrome (EGUS) is currently one of the more frequent diseases in horses. We aimed to identify changes in the salivary proteome in horses with EGUS at diagnosis and after successful treatment by using gel proteomics. Saliva samples were collected from nine horses with EGUS before and after treatment and nine matched healthy controls. SDS-PAGE (1DE) and two-dimensional gel electrophoresis (2DE) were performed, and significantly different protein bands and spots were identified by mass spectrometry. Horses with EGUS had increases in proteins such as adenosine deaminase (ADA), triosephosphate isomerase, keratins and immuno-globulin heavy constant mu and decreases in carbonic anhydrase (CA), albumin and prolactin-induced protein. These changes would indicate various physiopathological mechanisms involved in this disease, such as the activation of the immune system, decreased stomach defence mechanisms and inflammation. The treated horses presented lower expression levels of thioredoxin (TRX) after a successful treatment, in proteomics analysis and also measured with a commercially available ELISA kit. Overall, horses with EGUS have protein changes in their saliva when measured with gel proteomics compared with healthy horses, and they also showed changes after successful treatment. These proteins could be potential biomarkers for detection and monitoring treatment response in EGUS.

Automated Spectrophotometric Assays for the Measurement of Ammonia and Bicarbonate in Saliva of Horses: Analytical Validation and Changes in Equine Gastric Ulcer Syndrome (EGUS).

Ammonia (NH3) and bicarbonate (HCO3) have been related to gastric ulcers in humans. Ammonia is considered a possible cause of gastric ulcers, whereas bicarbonate has a protective function. The presence of ulcers in the stomach of horses is defined as Equine Gastric Ulcer Syndrome (EGUS), which is a frequent disease in this species, and it has been associated with changes in saliva composition, such as in analytes related to inflammation, immune system and oxidative stress. The objectives of this study were (1) to perform an analytical validation of two automated spectrophotometric assays, one for ammonia and one for bicarbonate, in the horses' saliva and (2) to evaluate their possible variations with EGUS. Analytical validation of the automated assays for ammonia and bicarbonate in the saliva of horses showed that both assays were precise and accurate. In addition, significantly higher values of ammonia and lower values of bicarbonate were found in the saliva of horses with EGUS compared to healthy horses. It can be concluded that ammonia and bicarbonate can be measured in the saliva of horses and that ammonia increases and bicarbonate decreases in this sample type could be related to the presence of EGUS in this species.

Risk Factors for Equine Gastric Ulcer Syndrome Incidence in Adult Icelandic Riding Horses.

A high prevalence of both squamous (ESGD) and glandular (EGGD) ulcers was previously found in, mainly young, Icelandic horses coming into training for the first time. This study evaluated risk factors for gastric ulcers in Icelandic riding horses at various ages and stages of training. The horses (n = 211) were gastroscoped from 21 equine establishments across Iceland. A variety of morphometric, clinical, behavioural and management factors were evaluated as potential risk factors for gastroscopically significant (grade ≥ 2/4: found in 27% of horses) or gastroscopically severe (grade 3 or 4/4: found in ~10% of horses) ESGD or gastroscopically significant EGGD (grade ≥ 1/2: found in 46.4%). Body condition score (BCS), cresty neck score (CNS), stable/turnout behaviour, exercise intensity/frequency and age were not significantly associated with ESGD or EGGD ulcer score. However, having come off the pasture into training for 4 weeks or less was a significant risk factor for gastroscopically significant and severe ESGD compared to 5 weeks or more. For both EGGD and ESGD, "region" was important. Gastroscopically significant EGGD and gastroscopically severe ESGD were more prevalent in those showing clinical signs often associated with ulcers. Geldings were more likely to have gastroscopically significant ESGD than both mares and stallions and more EGGD than stallions. Being stabled, but spending >2 h/day out in the paddock, compared with <2 h paddock time or full-time turnout, was protective for gastroscopically significant ESGD as was being fed complementary feed (all fed <1 g non-structural carbohydrate (NSC)/kg/BW/meal). Being at a training establishment for >4 weeks was protective for gastroscopically significant and gastroscopically severe ESGD but not EGGD. This study confirms the relatively low prevalence of ESGD in Icelandic horses being kept in training establishments and fed low NSC diets but highlights the high prevalence of EGGD.

Efficacy of the oral supplement, Equine Omega Complete, for the prevention of gastric ulcers and alpha-tocopherol supplementation in horses.

BACKGROUND: Omega-3 fatty acid and alpha-tocopherol supplementation reduces gastric ulcer formation in humans and rodents; however, efficacy of prevention in horses is unknown. Equine Omega Complete (EOC) is an oral supplement containing omega-3 fatty acids and alpha-tocopherol. HYPOTHESIS/OBJECTIVE: Determine if EOC supplementation prevents gastric ulcers and increases serum alpha-tocopherol concentrations in healthy horses. ANIMALS: Nine thoroughbred geldings; 5-13 years old. METHODS: Prospective randomized block design, repeated in crossover model. Horses were administered EOC, omeprazole, or water PO for 28 days. Horses underwent an established gastric ulcer induction protocol from days 21-28 via intermittent feed deprivation. Gastroscopies were performed on days 0, 21, and 28. Serum alpha-tocopherol concentrations were measured on days 0 and 28. The effects of treatment and time on ulcer grades were assessed with ordinal logistic regression, with significance at P-value <.05. RESULTS: Ulcer grades increased during ulcer induction in control and EOC but not omeprazole groups (P = .02). Grades increased in EOC-treated horses after ulcer induction from a median of 1 [95% confidence interval 0-2.5] (day 0) to 2.5 [1.5-3.5] (day 28) and were similar to the control group (P = .54). Serum alpha-tocopherol increased in EOC-treated horses from day 0 to day 28 (mean 2.2 ± 0.43 µg/mL to 2.96 ± 0.89 µg/mL; P < .001) with high individual variation; this increase was not different from omeprazole or control groups. CONCLUSION AND CLINICAL IMPORTANCE: Supplementation with EOC for 28 days did not prevent gastric ulcer formation nor increase alpha-tocopherol concentrations relative to the control group.

Changes in Calprotectin (S100A8-A9) and Aldolase in the Saliva of Horses with Equine Gastric Ulcer Syndrome.

Equine gastric ulcer syndrome (EGUS) is a highly prevalent disease that affects horses worldwide. Within EGUS, two different forms have been described: equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD). The associated clinical signs cause detrimental activity performance, reducing the quality of life of animals. Saliva can contain biomarkers for EGUS that could be potentially used as a complementary tool for diagnosis. The objective of this work was to evaluate the measurements of calprotectin (CALP) and aldolase in the saliva of horses as potential biomarkers of EGUS. For this purpose, automated assays for the quantification of these two proteins were analytically validated and applied for detecting EGUS in a total of 131 horses divided into 5 groups: healthy horses, ESGD, EGGD, combined ESGD and EGGD, and horses with other intestinal pathologies. The assays showed good precision and accuracy in analytical validation, and they were able to discriminate between horses with EGUS and healthy horses, especially in the case of CALP, although they did not show significant differences between horses with EGUS and horses with other diseases. In conclusion, salivary CALP and aldolase can be determined in the saliva of horses and further studies are warranted to elucidate the potential of these analytes as biomarkers in EGUS.

Changes in Management Lead to Improvement and Healing of Equine Squamous Gastric Disease.

Equine squamous gastric disease (ESGD) is common in horses and poses a serious welfare problem. Several risk factors have been identified and ESGD is routinely treated with omeprazole. Fourteen mares, previously used as embryo recipients and diagnosed with ESGD, were selected. Horses were confined to individual stalls, exercised once daily, and fed ad libitum hay, 1 kg of a low starch compound complementary feed and a mineral supplement. Half of the horses received a compound containing hydrolysed collagen (supplement) and the other half did not (control). At the start of the study, ESGD scores were 3.57 and 3.36 for the supplement and control group, respectively. After 4 weeks, the ESGD grades were significantly reduced in both groups (1.89 and 1.43, respectively, p < 0.01), and healing (ESGD < 2) occurred in 7 out of 14 horses. No treatment effect was observed (p = 0.75), and it was concluded that the change in husbandry overshadowed any potential effect of the compound. Severe ESGD can improve, and even heal, with the provision of a diet of ad libitum forage and a small amount of a compound complementary feed, without the use of omeprazole. A predictable daily routine, with a limited number of dedicated caretakers, may have contributed to the improvement of gastric health.

Changes in Proteins in Saliva and Serum in Equine Gastric Ulcer Syndrome Using a Proteomic Approach.

Changes in the salivary proteome in 12 horses with the two diseases included in equine gastric ulcer syndrome (EGUS), equine glandular gastric disease (EGGD) (n = 6) and equine squamous gastric disease (ESGD) (n = 6), were evaluated using a high-resolution LC-MS/MS analysis of TMT-labelled peptides and compared to 10 healthy control horses. Serum was also analysed for comparative purposes. The comparison between the horses with EGGD and controls showed significant changes in 10 salivary proteins, whereas 36 salivary proteins were differently abundant between ESGD and control groups. The most upregulated proteins in the case of EGGD were related to immune activation whereas, in horses with ESGD, the most significantly changed proteins were associated with squamous cell regulation and growth. Compared to serum, saliva showed a higher number of proteins with significant changes and a different pattern of changes. The proteins identified in our study, in addition to providing new information about the pathophysiological mechanisms in these diseases, could have the potential to be novel biomarkers for the diagnosis or monitoring of EGGD and ESGD.

Changes in Oxidative Status Biomarkers in Saliva and Serum in the Equine Gastric Ulcer Syndrome and Colic of Intestinal Aetiology: A Pilot Study.

Changes in the oxidative status of the blood of horses suffering from gastric ulcers and colic of intestinal aetiology (CIE) have been reported. However, saliva can also be a source of biomarkers of oxidative status. Therefore, this study aims to validate automated assays for the measurement of oxidative status biomarkers (ferric reducing ability of saliva/serum-FRAS/FRAP, cupric reducing antioxidant capacity-CUPRAC, the Trolox equivalent antioxidant capacity-TEAC, uric acid, and advanced oxidation protein products-AOPP) in the saliva and serum of horses, to assess their changes in the different ulcer gastric diseases (squamous-ESGD and glandular-EGGD) and CIE, and to evaluate their relationship with serum amyloid A (SAA), adenosine deaminase (ADA), and the systemic inflammatory response syndrome (SIRS) status. The assays showed a low imprecision and good linearity with enough sensitivity in both fluids. In EGGD, higher levels of FRAS, uric acid, and AOPP in saliva were observed compared to the healthy group, correlating with the salivary ADA levels. Horses with CIE showed increases in uric acid concentrations in serum associated with their SIRS status and outcome of the disease. In conclusion, analytes related to the oxidative status can be measured in the saliva and serum from horses by automated assays, and some of them can potentially be assessed as biomarkers in horses with gastric ulcers and CIE.

Prevalence of Gastric Ulceration in Horses with Enterolithiasis Compared with Horses with Simple Large Intestinal Obstruction.

Enterolithiasis is a well-documented cause of colic in horses, especially in some geographic areas such as California and Florida. This retrospective case-control study aims at comparing the prevalence of gastric ulcers in horses affected by enterolithiasis to that in horses affected by other types of large intestinal obstruction. Two hundred and ninety-six horses were included in the study sample. Horses that had surgery for the removal of one or more enteroliths were included in the study as cases. Patients that had surgery for large intestinal simple obstructions other than enterolithiasis (large colon displacement, non-strangulating large colon torsion, and large and small colon impactions) were selected to match case horses for age, sex, and breed and included as controls. A total of 101/148 horses with enteroliths (68%) had gastric ulcers diagnosed during hospitalization, compared with 46/148 of matched controls (31%). There was a significant association between enterolithiasis and gastric ulceration (odds ratio 4.76, p < 0.0001), and a greater prevalence in Thoroughbreds as compared with other breeds (odds ratio 22.6, p < 0.0001). We concluded that enterolithiasis is significantly associated with gastric ulceration (p < 0.0001). The association is stronger in Thoroughbreds.

Equine gastric ulcer syndrome in adult horses.

Many domesticated horses have gastric ulcers which can be diagnosed and graded during gastroscopy. A distinction should be made between equine squamous gastric disease (ESGD), which is caused by exposure of the mucosa to acid, and equine glandular gastric disease (EGGD), thought to occur when mucosal defence mechanisms are compromised. Horses with gastric ulcers may, but do not always, show clinical signs such as poor appetite, mild colic, discomfort during girthing, behavioural changes and reduced performance. The mainstay of treatment is blocking acid production using the proton pump inhibitor omeprazole. Treatment is usually successful in cases of ESGD, but less so for EGGD, where treatment duration is longer and for which sucralfate may be added or alternatives necessary, such as misoprostol, a prostaglandin analogue. To prevent recurrence of ulcers known risk factors, such as high concentrate diets, intense exercise and stress should be avoided or minimized.

Equine Gastric Ulcer Syndrome affects fitness parameters in poorly performing Standardbred racehorses.

Introduction: Equine Gastric Ulcer Syndrome (EGUS) is a highly prevalent disorder in horses, which can be classified, based on the localization of the lesions, as Equine Squamous Gastric Disease (ESGD) or Equine Glandular Gastric Disease (EGGD). Although EGUS is recognized as a common cause of poor performance in racehorses, objective investigations about its relation with athletic capacity are lacking. Therefore, the present retrospective study aims to evaluate the associations between EGUS severity and some fitness parameters measured during an incremental treadmill test in Standardbred racehorses in training. Methods: With this aim, data from 87 Standard bred racehorses which underwent a complete diagnostic evaluation for poor performance was reviewed. During gastroscopic examination, a 0-4 score was assigned to ESGD, while EGGD was evaluated for absence/presence; a total EGUS score was obtained by adding 1 point to ESGD score in horses showing concomitant EGGD. Fitness parameters obtained during incremental treadmill test included speed at a heart rate of 200 bpm (V200), speed and heart rate at a blood lactate of 4 mmol/L (VLa4, HRLa4), peak lactate, lactate and heart rate at 30 minutes post-exercise, maximum speed, minimum pH and maximum hematocrit. The associations between fitness parameters and EGUS and ESGD scores were evaluated by Spearman correlation, while Mann-Whitney test was used to compare them between horses with or without EGGD. Statistical significance was set at p<0.05. Results: EGUS grade was inversely correlated with V200 (p = 0.0025) and minimum pH (p = 0.0469); ESGD grade was inversely correlated with V200 (p = 0.0025) and VLa4 (p = 0.0363). Although a trend was observed, no significant differences in V200 were observed between horses with or without EGGD (p = 0.073); horses with EGGD reached a lower minimum pH (p = 0.0087). Discussion: These results show a negative association between aerobic capacity and EGUS, in particular ESGD. Although different hypotheses have been proposed, including abdominal pain and decreased appetite due to lactate accumulation, the underlying mechanisms are still unknown, and it is not clear whether EGUS represents a cause or a consequence of an early lactate accumulation and post-exercise acidosis.

Gastric microbiome in horses with and without equine glandular gastric disease.

BACKGROUND: The role of the gastric microbiome in development or persistence of equine glandular gastric disease (EGGD) remains to be investigated. HYPOTHESIS/OBJECTIVES: The objective was to characterize the glandular mucosal and gastric fluid microbiomes of horses with and without EGGD. It was hypothesized that differences in the mucosal microbiome are associated with EGGD. ANIMALS: Twenty-four horses were enrolled. METHODS: Gastroscopy was performed and EGGD scores recorded (score 0, n = 6; score 1, n = 8; score ≥2, n = 10). Gastric fluid and pinch biopsies of healthy glandular mucosa and EGGD lesions were collected via gastroscope. 16S rRNA amplicon sequencing of the gastric fluid and glandular mucosal biopsies was performed. Relationships between gastric fluid and mucosal microbial community composition were evaluated among EGGD score groups (EGGD 0-BX, EGGD 1-BX, EGGD ≥2-BX) and among endoscopic appearances: controls from horses without EGGD and normal areas, hyperemic areas, and lesions from horses with EGGD. RESULTS: Microbial community structure of mucosal biopsies differed among EGGD score groups (Jaccard similarity index; P = .009). Principal coordinate analysis showed separate clusters for EGGD 0-BX and EGGD ≥2-BX. CONCLUSIONS AND CLINICAL IMPORTANCE: A modest difference was detected in the community structure of the gastric glandular mucosal microbiome in association with EGGD score.

Interobserver and intraobserver reliability for 2 grading systems for gastric ulcer syndrome in horses.

BACKGROUND: Grading of equine gastric ulcer syndrome (EGUS) is undertaken in clinical and research settings, but the reliability of EGUS grading systems is poorly understood. HYPOTHESIS/OBJECTIVES: Investigate interobserver and intraobserver reliability of an established ordinal grading system and a novel visual analog scale (VAS), and assess the influence of observer experience. ANIMALS: Sixty deidentified gastroscopy videos. METHODS: Six observers (3 specialists and 3 residents) graded videos using the EGUS Council (EGUC) system and VAS. Observers graded the videos three 3 for each system, using a cross-over design with at least 1 week between each phase. The order of videos was randomized for each phase. METHODS: Interobserver and intraobserver reliability were estimated using Gwet's agreement coefficient with ordinal weights applied (AC2) for the EGUC system and the intraclass correlation coefficient (ICC) for the VAS. RESULTS: Using the EGUC system, interobserver reliability was substantial for squamous (AC2 = 0.69; 95% confidence interval [CI], 0.57-0.80) and glandular mucosa (AC2 = 0.72; 95% CI, 0.70-0.75), and intraobserver reliability was substantial for squamous (AC2 = 0.80; 95% CI, 0.71-0.90) and glandular mucosa (AC2 = 0.80; 95% CI, 0.74-0.86). Interobserver reliability using the VAS was moderate for squamous (ICC = 0.64; 95% CI, 0.31-0.96) and poor for glandular mucosa (ICC = 0.35; 95% CI, 0.06-0.64), and intraobserver reliability was moderate for squamous (ICC = 0.74; 95% CI, 0.62-0.86) and glandular mucosa (ICC = 0.56; 95% CI, 0.39-0.72). CONCLUSIONS AND CLINICAL IMPORTANCE: The EGUC system had acceptable intraobserver and interobserver reliability and performed well regardless of observer experience. Familiarity and observer experience improved reliability of the VAS.

Effect of omeprazole and sucralfate on gastrointestinal injury in a fasting/NSAID model.

BACKGROUND: Equine gastric ulcer syndrome (EGUS) is a common and significant cause of morbidity in horses, with a range of clinical signs, including inappetence, colic and poor performance. Hospitalised horses are exposed to factors that may induce EGUS, including fasting and nonsteroidal anti-inflammatory drug (NSAID) administration, and may be at risk for development of squamous (ESGD) and glandular gastric disease (EGGD). Prophylactic anti-ulcer medication is often prescribed for these patients, but drug selection is complicated by different aetiology and response to treatment of ESGD and EGGD. OBJECTIVES: To establish the efficacy of sucralfate or omeprazole used prophylactically in horses exposed to a combined feed-fast and NSAID administration EGUS induction protocol. We hypothesised that these drugs would be equally effective for prevention of gastric lesions in the experimental cohort. STUDY DESIGN: Randomised crossover experimental design. METHODS: Horses (n = 14) received either omeprazole (1 mg/kg PO q24h) or sucralfate (20 mg/kg PO q8h) while undergoing the feed-fast/NSAID protocol, allowed an 8-week washout period, and then administered the alternate treatment. Serial gastroscopy, ultrasound and haematology documented treatment effects. RESULTS: ESGD and EGGD score increased over time under both treatments. There was a significant effect of treatment on EGGD scores (P < .001), with post-treatment EGGD scores higher for horses receiving sucralfate (median 3; IQR 2.25,3) than omeprazole (1; 1,1). The effect of treatment on ESGD scores just achieved significance (P = .05), with post-treatment ESGD scores higher for sucralfate (4; 3,4) than omeprazole (2; 2,3). MAIN LIMITATIONS: This study was performed in healthy horses, and response to treatment may differ in horses with clinical illness. Additional investigation in a larger population may be required to detect significant differences in other clinical parameters. CONCLUSIONS: Omeprazole was superior to sucralfate for mitigating gastric lesion severity in healthy horses exposed to a feed-fast/NSAID model.

Effect of oral administration of omeprazole on the microbiota of the gastric glandular mucosa and feces of healthy horses.

BACKGROUND: Omeprazole administration is associated with changes in gastric and fecal microbiota and increased incidence of Clostridioides difficile enterocolitis in humans and dogs. HYPOTHESIS/OBJECTIVES: Study purpose was to assess the effect of omeprazole on gastric glandular and fecal microbiota in healthy adult horses. ANIMALS: Eight healthy horses stabled on straw and fed 100% haylage. METHODS: Prospective controlled study. Transendoscopic gastric glandular biopsies, gastric fluid, and fecal samples were obtained from each horse twice at a 7-day interval before the administration of omeprazole. Samples were taken on the same horses before and after a 7-day administration of omeprazole (4 mg/kg PO q24h). pH was assessed on fresh gastric fluid and other samples were kept at -20°C until analysis. Bacterial taxonomy profiling was obtained by V1V3 16S amplicon sequencing from feces and gastric glandular biopsies. Analysis of alpha, beta diversity, and comparison between time points were performed with MOTHUR and results were considered significant when P < .05. RESULTS: Gastric pH increased significantly after 7 days of omeprazole administration (P = .006). Omeprazole did not induce significant major changes in composition of fecal or gastric glandular microbiota, however, after administration, certain microbial genera became more predominant in the gastric glandular mucosa (lower Simpson's evenness, P = .05). Only the genus Clostridium sensu strictu_1 had a significant shift in the glandular gastric mucosa after omeprazole administration (P = .002). No population shifts were observed in feces. CONCLUSIONS AND CLINICAL IMPORTANCE: Oral administration of omeprazole could have fewer effects in gastrointestinal microbiota in the horse compared to other species.

Misoprostol is superior to combined omeprazole-sucralfate for the treatment of equine gastric glandular disease.

BACKGROUND: Previous studies have demonstrated a poor response to healing of gastric glandular lesions with oral omeprazole and other medications. OBJECTIVES: To evaluate the efficacy of two novel treatments (misoprostol [M] and combined omeprazole-sucralfate [OS]) in horses for gastric glandular disease. STUDY DESIGN: Prospective, clinical study. METHODS: Sixty-three sports horses with grade >1/4 glandular disease were identified by gastroscopy. Horses received either 5 µg/kg of misoprostol per os BID 1 h prior to feeding or a combination of 4 mg/kg enteric coated omeprazole per os SID and 12 mg/kg sucralfate per os BID where drugs were given 1 h prior to feeding and sucralfate given 60 min after omeprazole; allocation was dependent upon centre. Gastroscopy was repeated at 28-35 days. Evaluators of the gastroscopy images were blinded to the treatments the horses received and images were reviewed independently. RESULTS: The most common presenting sign in both treatment groups was poor performance (Overall - 65.1%; M - 60.5% and OS - 75%). Overall healing (P<0.001; OR = 11 [2.8-45]) and improvement (P = 0.006; OR = 11 [1.9-59]) of lesions were associated with resolution of clinical signs. Misoprostol was shown to be superior to combined omeprazole-sucralfate both for healing (M - 72% [95% CI 43-67] and OS - 20% [95% CI 7-41]; P<0.001) and improvement (M - 98% [95% CI 90-100] and OS - 65% [95% CI 43-83]; P<0.001). MAIN LIMITATIONS: Relatively small, clinical study, reliance on client questionnaire data, clients not blinded to the treatments the horse received, diet could have affected drug pharmacodynamics although mimics clinical practice and no validated scoring system available for glandular lesions. CONCLUSIONS: These results suggest that gastric glandular disease does indeed result in clinical signs. In this population of horses, misoprostol was superior to omeprazole and sucralfate and warrants further evaluation in a large scale, multi-centre trial.