The effect of porcine hydrolysed collagen on gastric ulcer scores,gastric juice pH,gastrin and amino acid concentrations in horses

Gastric ulcers are common in horses. The purpose of this study was to test the effect of porcine hydrolysed collagen (PHC) on gastric ulcer scores and gastric juice pH in horses. We hypothesise that PHC-administration will result in improved gastric lesion scores and act synergistically with omeprazole to improve treatment efficacy. Thoroughbred horses (n = 10) were studied in a 2-period, 2-treatment crossover design, where the PHC (45 g) was administered twice daily. Horses were treated for 56 days. Gastroscopy was performed and gastric juice pH measured on Days 0, 14, 28, 42, 49 and 56. Nonglandular gastric ulcer number (NGN) and severity (NGS) and glandular ulcer number (GN) and glandular severity (GS) scores were assigned by an investigator masked to treatment and serum gastrin and amino acid concentrations. By Day 42, 2 weeks after discontinuing omeprazole treatment, NGN and NGS scores returned to pretreatment values and serum gastrin was higher when compared to values measured on Day 28. By Day 49, after the feed-deprivation period, NGN and NGS were similar to pretreatment values. By Day 56, mean NGN score was significantly lower in PHC-treated horses, compared to controls. Mean gastric juice pH significantly increased in both groups on Day 28 and the pH was significantly (P = 0.0127) higher in the PHC-treated horses. Serum amino acid concentrations were not significantly different 2 h after feeding PHC and hydroxyproline was not detected. Serum gastrin concentration did not increase 2 h after feeding in the PHC-fed horses. The PHC fed to horses enhanced the effects of omeprazole on increased gastric juice pH, inhibited gastrin secretion after feeding and resulted in fewer nonglandular ulcers after long-term feeding (56 days) in stall-confined horses undergoing intermittent feeding.     

Effects of intravenously administrated omeprazole on gastric juice pH and gastric ulcer scores in adult horses

The study was performed to evaluate the efficacy of omeprazole powder in sterile water, administered intravenously, on gastric juice pH in adult horses with naturally occurring gastric ulcers. Omeprazole (0.5 mg/kg, IV) was administered once daily for 5 days to 6 adult horses with gastric ulcers. Gastric juice was aspirated through the biopsy channel of an endoscope and pH was measured before and 1 hour after administration of omeprazole on day 1, and then before and after administration of omeprazole on day 5. Gastric ulcer scores were recorded on day 1 before administration of omeprazole and on day 5, 23 hours after the 4th daily dose. Gastric juice pH and ulcer scores were compared between the times. When compared with the pre-injection value (2.01 +/- 0.42), mean +/- SD gastric juice pH was significantly higher when measured 1 hour after administration of the initial dose (4.35 +/- 2.31), and before (5.27 +/- 1.74) and 1 hour after (7.00 +/- 0.25) administration of omeprazole on day 5. Nonglandular gastric ulcer number score significantly decreased from a mean +/- SD of 3.2 +/- 0.80 to 2.0 +/- 1.1, but nonglandular gastric ulcer severity score remained the same. Few glandular ulcers were seen in the study, and scores did not change. Because of its potent and long duration of action on gastric juice pH, this intravenous formulation of omeprazole may show promise for treatment of equine gastric ulcer syndrome (EGUS) in horses with dysphagia, gastric reflux, or other conditions that restrict oral intake of omeprazole paste. Aspiration of gastric juice and measurement of pH can be of use to determine whether the desired pH > 4.0 has been reached after omeprazole treatment.     

Validation of a transendoscopic glandular and nonglandular gastric biopsy technique in horses

Reasons for performing study: In order to study the evolution of histopathological and immunohistochemical changes in the gastric mucosa of horses with EGUS (equine gastric ulcer syndrome), a feasible, useful, valid and safe in vivo gastric biopsy technique is required. Objectives: To determine the average gastric mucosal healing time following endoscopic gastric biopsy sampling, and evaluate the feasibility, safety and usefulness of samples obtained by this method for histopathological analysis. Methods: Six mature mares from the Faculté de Médecine Vétérinaire research herd were used. Transendoscopic gastric biopsy was performed on Days 0 and 9 using a flexible forceps with oval and fenestrated jaws to obtain gastric mucosal samples from 4 different sites: cardia (C), fundus (F), margo plicatus (MP) and glandular mucosa (GL). A maximum of 4 samples per site was taken and processed routinely for histopathology, evaluated by a pathologist. On Days 1–4 and 9–11 the lesions created by the biopsies were evaluated by gastroscopy. Lesions were evaluated over time based on a score from 0–4, where 4 was the most severe. Results: Biopsy samples could be obtained from all targeted sites except C. No abnormal clinical signs were observed up to 7 days post biopsy. The average biopsy lesion scores decreased significantly with time for all sites. The average lesion score was significantly higher for the MP compared to the other sites at Days 1 and 2. Samples taken from the nonglandular portion of the stomach were considered inadequate for histopathology, while those taken from the glandular mucosa were adequate. Conclusion: The transendoscopic gastric biopsy technique described here is a feasible, safe and useful technique for obtaining samples from the equine gastric glandular mucosa. Although biopsy samples could be obtained from several areas in the nonglandular mucosa, these were very small, took longer to heal and were not considered adequate for histopathological evaluation, and another technique should therefore be validated.     

Prevalence of gastric ulcer syndrome in high-level endurance horses

Reasons for performing the study: Equine gastric ulcers syndrome (EGUS) prevalence studies are rare in the endurance horse and none has been carried out to date in horses competing at high level. Objectives: To determine the prevalence of EGUS in high‐level endurance horses. Methods: Thirty endurance horses competing at high level were selected and submitted to 2 gastroscopic examinations. The first gastroscopy was performed during the interseason period, and the second during the competition season within 2–3 days following a ride of 90–160 km. Data related to housing, feeding, training system as well as age, breed and gender were recorded for each horse. Results: The prevalence of squamous gastric ulcers was 48% during the interseason period (mean score 0.85 ± 0.13 on a scale from 0–4) and 93% during the competition season (mean score 1.60 ± 1.15) with a highly significant difference between the seasons (P = 0.001). Most of the lesions were situated in the squamous portion of the stomach but 33.3% of horses showed also glandular lesions. Significant influence of training and performance level on the gastric score (according to the distance of the ride preceding the second gastroscopy) was shown (P = 0.038). There was also a significant influence of housing on the gastric score (P = 0.002) showing higher scores in the horses kept totally on pasture (mean score: 2.14 ± 0.14) vs. horses housed in a mixed environment (stable + pasture, mean score: 1.43 ± 0.17). Both the pastured and (stabled + pastured) groups were receiving a grain supplement but the pastured group received a higher daily starch intake, which might explain the higher ulcer prevalence. There was no influence of age, breed or gender on the gastric scores. Conclusions: The high prevalence of gastric lesions observed in this study is probably related to the high level of training and performance of the horses examined compared to the population of horses included in the prior study. Potential relevance: This prevalence of EGUS in high‐level endurance horses is comparable to the prevalence established in racing horses. The equine veterinarians may take into consideration EGUS as a potential cause of poor performance.     

Effects of intravenously administered esomeprazole sodium on gastric juice pH in adult female horses

Background: Gastric ulcers are common in horses and treatment of horses that cannot be administered oral medication can be problematic. Objectives: To evaluate the efficacy of esomeprazole sodium administered intravenously on gastric juice pH and gastric ulcer scores in horses. Animals: Twelve adult female Quarter Horses. Methods: Esomeprazole sodium (0.5 mg/kg IV) was administered once daily to 8 horses (treatment group) and saline (5 mL IV) was administered to 4 horses (control group) for 13 consecutive days. Gastroscopy was performed and gastric juice pH and gastric ulcer score were recorded before and 1 hour after the administration of esomeprazole sodium or saline on days 1 and 5, then on day 14, 23 hours after the 13th daily dose of esomeprazole sodium or saline. Results: When compared with values before treatment, gastric juice pH was higher in esomeprazole sodium‐treated horses after treatment (4.25 ± 2.39 versus 6.43 ± 1.18; P= .002). Also, gastric juice pH was higher (P= .001) in esomeprazole sodium‐treated horses compared with saline‐treated control horses on day 5 and on day 14 values. Gastric ulcers were seen in 5/12 (43%) horses in the study. Conclusions and Clinical Importance: Esomeprazole sodium shows promise for treatment of gastric ulcers in horses with signs of dysphagia, gastric reflux, or other conditions that restrict oral intake of the current Federal Drug Administration‐approved omeprazole paste.     

Effect of paddock vs. stall housing on 24 hour gastric pH within the proximal and ventral equine stomach

REASONS FOR PERFORMING STUDY: Stall housing has been suggested as a risk factor for ulcer development in the equine stomach; however, the exact pathogenesis for this has not been established. OBJECTIVES: To investigate the effect of 3 environmental situations (grass paddock, stall alone or stall with adjacent companion) on pH in the proximal and the ventral stomach. METHODS: Six horses with permanently implanted gastric cannulae were used in a randomised, cross-over, block design. Each horse rotated through each of three 24 h environmental situations. Horses remained on their normal diet (grass hay ad libitum and grain b.i.d.) throughout the study. Intragastric pH was measured continuously for 72 h just inside the lower oesophageal sphincter (proximal stomach) and via a pH probe in the gastric cannula (ventral stomach). RESULTS: Neither proximal nor ventral 24 h gastric pH changed significantly between the 3 environmental situations. Mean hourly proximal gastric pH decreased significantly in the interval from 01.00-09.00 h compared to the interval from 13.00-20.00 h, regardless of environmental situation. Median hourly proximal pH only differed in the interval from 06.00-07.00 h compared to the interval 14.00-19.00 h. Neither mean nor median hourly ventral gastric pH varied significantly with the time of day. CONCLUSIONS: The change in housing status used in the current study did not affect acid exposure within either region of the equine stomach. The pH in the ventral stomach was uniformly stable throughout the study, while the proximal pH demonstrated a 24 h circadian pattern.     

Effect of a feed/fast protocol on pH in the proximal equine stomach

Reasons for performing study: Risk factors for the development of gastric squamous ulcers include various management procedures, such as intermittent feed deprivation that can occur during weight management regimens or stall and dry lot confinement. Objectives: To investigate the effect of intermittent feed deprivation relative to continuous feed intake on proximal intragastric pH, specifically in the region of the squamous mucosa of the lesser curvature. Methods: In 6 horses, pH electrodes were placed just inside of the oesophageal sphincter in the stomach for each of two 72 h protocols (A and B) in a randomised, cross‐over design. Protocol A consisted of 12 h fed, 12 h fasted, 24 h fed and 24 h fasted, in sequence. Protocol B consisted of 72 h fed. During the fed periods of each protocol, horses had ad libitum access to coastal Bermuda hay and were fed sweet feed (1 kg, b.i.d.). Horses had ad libitum access to water at all times. Results: Proximal intragastric pH was significantly lower during protocol A, than during protocol B. However, hourly mean pH was significantly different only during the day and evening hours between protocols. During protocol B, mean proximal pH decreased significantly from 03.00 to 09.00 compared to 19.00 to 23.00 h. A moderate positive correlation of hay intake vs. proximal gastric pH could be established. Conclusions: Intermittent feed deprivation decreased proximal gastric pH in horses relative to those horses for which feed was not restricted. However, the effect was only significant when fasting occurred during the day and evening hours, as a nocturnal decrease in pH occurred simultaneously in the fed horses. Potential relevance: Episodes of daytime feed deprivation should be avoided if possible, as proximal gastric acid exposure rapidly increases during such events.     

Courses for horses: Rethinking the use of proton pump inhibitors in the treatment of equine gastric ulcer syndrome

Oral omeprazole has been the cornerstone of equine gastric ulcer syndrome (EGUS) treatment for nearly 20 years. However, approximately 15–30% of equine squamous gastric disease (ESGD) cases and 75% of equine glandular gastric disease (EGGD) cases fail to heal within current treatment guidelines. Recently, a number of factors that may affect the efficacy of oral omeprazole have been highlighted and the pharmacodynamics of a number of novel proton pump inhibitors (PPIs) have been described in the horse. The purpose of this article is to review the factors that affect oral omeprazole efficacy, with the goal of maximising therapeutic response, and the novel PPIs recently described.     

Effect of a commercial anionic dietary supplement on urinary pH and concentrations of electrolytes and pH in blood of horses

ABSTRACT

Aims: To compare urine urinary pH, blood pH and concentration of electrolytes in blood of healthy horses fed an anionic salt supplement to achieve diets with a dietary cation-anion difference (DCAD) of ?40 or 0?mEq/kg DM, with horses a fed a diet with a DCAD of 85?mEq/kg DM.

Methods: Eight healthy horses received each of three diets in a randomised crossover design. Diets consisted of grass hay and concentrate feed, with a varying amount of an anionic supplement to achieve a DCAD of 85 (control), 0 or ?40?mEq/kg DM. They were fed for 14 days each with a washout period of 7 days between. Urine pH was measured daily and blood samples were collected on Days 0, 7 and 14 of each study period for the measurement of pH and concentration of electrolytes.

Results: Four horses voluntarily consumed the anionic supplement with their feed, but four horses required oral supplement administration via dose syringe. During the study period mean urine pH was lower in horses fed diets with a DCAD of 0 (6.91; SD 0.04) and ?40 (6.83; SD 0.04) mEq/kg DM compared to the control diet (7.30; SD 0.04). Compared with horses fed the control diet, mean urine pH was lower in horses fed the 0 and ?40?mEq/kg DM diets on Days 1–12 and 14 (p?<?0.05) of the study period. On Day 13 it was only lower in horses fed the ?40?mEq/kg DM diet (p?<?0.01). Urine pH was similar for horses fed the 0 and ?40?mEq/kg DM diets (p?=?0.151). The DCAD of the diet had no effect on blood pH, ionised Ca or anion gap. Mean concentrations of bicarbonate in blood were affected by diet (p?=?0.049); they were lower when horses were fed the 0?mEq/kg diet relative to the control diet on Day 14.

Conclusions and clinical relevance: The anionic supplement reduced urine pH in horses fed diets with a DCAD of 0 or ?40?mEq/kg DM compared with 85?mEq/kg DM. However as urinary pH did not fall below pH 6.5, the pH below which calcium carbonate uroliths do not form, this reduction in urine pH is unlikely to be clinically significant. The supplement was variably palatable and showed minimal promise as an effective urinary acidifier at the doses administered in this study.     

Effect of a novel rice fermented extract on gastric ulcers in horses

Gastric ulcers cause appetite loss, poor body condition, and colic in horses. This study investigated the protective effect of a rice fermented extract on the gastric mucosa in 17 healthy Thoroughbreds. For one month, horses in the rice fermented extract (nine horses) and control (eight horses) groups were orally administered a rice fermented extract (100%; 0.2 ml/kg, SID) and tap water (0.2 ml/kg), respectively. Gastric endoscopic images were obtained before and one month after rice fermented extract administration. The gastric ulcer score was lower after administration (median, 1; maximum, 2; minimum, 1) than before administration (median, 4; maximum, 4; minimum, 3) in the rice fermented extract group (P<0.05). In conclusion, the administration of a rice fermented extract for one month improves gastric mucosal lesions in Thoroughbreds with gastric ulcers.