Pathomorphological study on gastroduodenal ulceration in horses: localisation of lesions

Equine Squamous Gastric Disease: Prevalence, Impact and Management

This narrative review explores the etiopathogenesis, clinical signs, diagnosis and treatment of ESGD (equine squamous gastric disease) and discusses the impact of this commonly encountered condition on the equine industry. ESGD refers specifically to peptic injury of the squamous mucosa of the stomach. Prevalence is highest in performance horses, but the disease has been documented across many breeds and ages, including in feral horses and foals. The pathogenesis of ESGD is well understood. Intensive management and exercise are important factors that contribute to a disruption of the normal stratification of gastric pH. This results in exposure of the vulnerable squamous mucosa to acid, leading to ulceration. Clinical signs are variable and there is little evidence to support a direct association between reported signs and the presence or absence of lesions seen on gastroscopy. Management is aimed at acid suppression and mitigation of known risk factors.

Effects of a nutraceutical supplement in the management of mild equine squamous gastric disease in endurance horses

INTRODUCTION

Equine squamous gastric disease (ESGD) may require prolonged treatments with acid suppressants; therefore, interest in nutraceutical supplements with anti-ulcerogenic properties has increased. This study aims to investigate the efficacy of Trophogast pellet for the treatment of ESGD in endurance horses.

MATERIAL AND METHODS

Fifteen endurance horses were included based on their gastroscopic examination and randomly assigned to a treatment group, receiving Trophogast pellet for 30 days together with management changes, or to a control group, only subjected to management modifications. At the end of treatment, gastroscopy was repeated. Scores were assigned according to the Equine Gastric Ulcer Council scoring system. All horses were weighed at the beginning and at the end of the study. ESGD grades and weight before and after treatment were compared.

RESULTS

At enrolment, median ESGD score in the treatment group was 2, while in the control group it was 1. After the treatment period, a significant decrease in ESGD grade was observed in the treatment group (median 1, p = 0.0078), while there was no change in the control group (median 2). No significant weight change was observed in either group.

CONCLUSION

Trophogast pellet was effective at promoting healing of mild ESGD in endurance horses.

Taxonomic review of Gasterophilus (Oestridae, Gasterophilinae) of the world, with updated nomenclature, keys, biological notes, and distributions

A taxonomic review of Gasterophilus is presented, with nine valid species, 51 synonyms and misspellings for the genus and the species, updated diagnoses, worldwide distributions, and a summary of biological information for all species. Identification keys for adults and eggs are elaborated, based on a series of new diagnostic features and supported by high resolution photographs for adults. The genus is shown to have its highest species richness in China and South Africa, with seven species recorded, followed by Mongolia, Senegal, and Ukraine, with six species recorded.

Gasterophilus flavipes (Oestridae: Gasterophilinae): A horse stomach bot fly brought back from oblivion with morphological and molecular evidence

Species of Gasterophilus Leach are obligate parasites in domestic and wild equids and responsible for cosmopolitan gasterophilosis. Although with only eight species known so far, they have received considerable attention because of their significant veterinary and economic importance. Surprisingly, we found that G. flavipes (Olivier) is a valid species based on morphological characters from male, female and the egg, after spending half a century as a synonym of G. haemorrhoidalis (Linnaeus). In the present study, G. flavipes, G. haemorrhoidalis and G. inermis (Brauer), which are the three closely related species possessing a remarkable mixture of shared morphological characters, are diagnosed and comparatively redescribed; the key to separate adults and eggs are provided, together with a series of high-resolution photographs from all the body parts. COI barcodes do not allow for a separation of G. flavipes, G. haemorrhoidalis and G. inermis, but showed a closer relationship between G. flavipes and G. haemorrhoidalis than the other two combinations, which is consistent with the morphological evidence. Geographically, G. flavipes seems to be common and widespread in the warmer parts of the Palaearctic region. Thus, the epidemiology of gasterophilosis where G. flavipes is known or supposed to occur calls for a more careful veterinarian re-assessment. A decline in the populations of Gasterophilus spp. has been noticed in Europe, but all seven Palaearctic species of Gasterophilus appear to maintain stable populations in Xinjiang (China), which may be explained by a higher biodiversity of equids and less use of anti-parasitic treatments in Xinjiang than in Europe. Our study shows that morphological characters still provide the solid backbone in classification of Gasterophilus at species-level, and updated diagnoses and a key is provided to distinguish G. flavipes, G. haemorrhoidalis and G. inermis, and to facilitate studies of epidemiology, phylogeny and host-parasite co-evolution.

The antenna of horse stomach bot flies: morphology and phylogenetic implications (Oestridae, Gasterophilinae: Gasterophilus Leach)

Antennae are among the most elaborate sensory organs in adult flies, and they provide rich information for phylogenic studies. The antennae of five out of eight species of Gasterophilus Leach (G. haemorrhoidalis (Linnaeus), G. intestinalis (De Geer), G. nasalis (Linnaeus), G. nigricornis (Loew) and G. pecorum (Fabricius)), were examined using scanning electron microscopy. The general morphology, including distribution, type, size, and ultrastructure of antennal sensilla were presented, and the definition of auriculate sensilla and sensory pits were updated and clarified. Eighteen antennal characters were selected to construct the first species-level phylogeny of this genus. The monophyly of Gasterophilus was supported by the presence of coeloconic sensilla III on the antennal arista. The species-level cladogram showed G. pecorum branching off at the base, and the remaining species forming the topology (G. intestinalis+ (G. haemorrhoidalis+ (G. nasalis+ G. nigricornis))). Our research shows the importance of the antennal ultrastructure as a reliable source for phylogenetic analysis.

Effect of pectin, lecithin, and antacid feed supplements (Egusin®) on gastric ulcer scores, gastric fluid pH and blood gas values in horses

Background

The objectives of this study were to evaluate the effects of two commercial feed supplements, Egusin 250^® [E-250] and Egusin SLH^® [E-SLH], on gastric ulcer scores, gastric fluid pH, and blood gas values in stall-confined horses undergoing feed-deprivation.

Methods

Nine Thoroughbred horses were used in a three-period crossover study. For the three treatment groups, sweet feed was mixed with E-250, E-SLH, or nothing (control group) and fed twice daily. Horses were treated for 21 days, then an additional 7 days while on an alternating feed-deprivation model to induce or worsen ulcers (period one). In periods two and three, horses (n=6) were treated for an additional 7 days after feed-deprivation. Gastroscopies were performed on day -1 (n=9), day 21 (n=9), day 28 (n=9) and day 35 (n=6). Gastric juice pH was measured and gastric ulcer scores were assigned. Venous blood gas values were also measured.

Results

Gastric ulcers in control horses significantly decreased after 21 days, but there was no difference in ulcer scores when compared to the Egusin® treated horses. NG gastric ulcer scores significantly increased in E-250 and control horses on day 28 compared to day 21 as a result of intermittent feed-deprivation, but no treatment effect was observed. NG ulcer scores remained high in the control group but significantly decreased in the E-SLH- and E-250-treated horses by day 35. Gastric juice pH values were low and variable and no treatment effect was observed. Mean blood pCO₂ values were significantly increased two hours after feeding in treated horses compared to controls, whereas mean blood TCO₂ values increased in the 24 hour sample, but did not exceed 38 mmol/l.

Conclusions

The feed-deprivation model increased NG gastric ulcer severity in the horses. However, by day 35, Egusin^® treated horses had less severe NG gastric ulcers compared to untreated control horses. After 35 days, Egusin^® products tested here ameliorate the severity of gastric ulcers in stall-confined horses after feed stress.

The influence of two lucerne-based forage feeds, FiberProtect® and FiberEdge® on Equine Gastric Ulcer Syndrome in horses

Equine Gastric Ulcer Syndrome (EGUS) is extremely prevalent in both racing and non-racing horse populations. The exact aetiology of EGUS is unclear but many stress related risk factors have been implicated including the feeding of grain-based diets. Current treatment techniques often necessitate drug therapy which, when added to feed costs, can be expensive and may have a detrimental effect on digestion due to the mode of action of these therapies. The following experiment set out to investigate if feeding fermented, forage-based feeds (Modified Bio-Fermentation (MBF) lucerne feeds treated with Xanotyde®, registered as FiberProtect® and FiberEdge®; Fiber Fresh Feeds Ltd, Reporoa, New Zealand), could assist in the healing and prevention of ulceration. Nine adult horses with demonstrable and sustained gastric ulceration (diagnosed by gastric endoscopy), were used in a two part study. The first 42 d healing phase investigated the impact of feeding FiberProtect® (FPT) or FiberEdge® (FED) on established gastric ulcers. After 14 d on these diets 44% (4/9) of horses had no ulceration or hyperaemia (inflammation) (EGUC grade 0) and all horses were ulcer free (EGUC grade 0) at d 42. A significant (P < 0.01) relationship was determined between length of time fed and disappearance of ulcers (R2 = 0.9004; DF = 2). The prevention phase utilised the same horses, ulcer-free at d 42, and fed them a grain-based high energy racing diet alongside FPT at 40% and 60% of the total diet (DM basis). The horses were monitored for a further 28 d (d 42 – d 70), and only three showed a recurrence of ulceration throughout this period. At d 70, eight out of nine horses were ulcer free (EGUC grade 0). The findings suggest that FPT and FED can be used to heal and prevent gastric ulceration, and that FPT can be fed alongside a high grain diet to prevent recurrence of gastric ulcers.

Endoscopic findings of the stomach in pleasure horses in Poland

BACKGROUND

This study was performed to determine the prevalence of ulcers in the gastric squamous and glandular mucosa in Polish pleasure horses.

STUDY DESIGN

Medical records from gastroscopic examinations of 108 pleasure horses of different breeds were reviewed. The study population consisted of two groups; group I (n = 48) with horses that expressed mild clinical signs of gastric ulcer syndrome (EGUS) including poor appetite, slight weight loss or poor body condition, and group II (n = 60) with horses that had no signs of gastrointestinal problems. The age range was 4-10 years, including 5 males, 34 castrated males (geldings) and 69 mares. The prevalence, distribution and severity of gastric ulcers were recorded. Lesions involving the squamous mucosa and the glandular mucosa of the antrum and pylorus were graded and compared between groups.

RESULTS

Significant difference was found in the presence and severity of gastric ulcers between the two groups of horses. The overall prevalence of gastric ulcers in the first group of horses (n = 48) was 59% while in the group of clinically healthy horses (n = 60) the prevalence of gastric lesion was 40% (P = 0.004). Almost 19% of horses from group I had between 6-10 lesions (EGUS score III) and nearly 19% had either >10 localized lesions or very large diffuse lesions (EGUS number score IV). The number of ulcerations in affected horses were significantly lower in group II compared to group I (P = 0.016) as 10% of horses had 6-10 lesions (EGUS number score III) and nearly 14% had either >10 localized lesions or very large diffuse lesions (EGUS number score IV). Gastroscopy revealed that nearly 32% of horses from the second group had an ulceration EGUS score ≥ II.

DISCUSSION AND CONCLUSIONS

This study confirms that gastric ulcerations can be prevalent in apparently clinically normal pleasure horses and a complete gastroscopic examination including the examination of the pylorus is advisable to evaluate this syndrome.

Expression of cyclooxygenase isoforms in ulcerated tissues of the nonglandular portion of the stomach in horses

OBJECTIVE

To characterize the expression of the cyclooxygenase (COX)-1 and COX-2 isoforms in naturally occurring ulcers of the nonglandular portion of the stomach in horses. SPECIMEN POPULATION: 38 specimens from ulcerated stomachs and 10 specimens from healthy stomachs.

PROCEDURES

Specimens were collected at an abbatoir; for each specimen of squamous gastric mucosa, 1 portion was fixed in neutral-buffered 10% formalin for immunohistochemical analysis and another was frozen at -70 degrees C for immunoblotting analysis. Immunoreactivity to 2 antibodies, MF241 (selective for COX-1) and MF243 (selective for COX-2), was evaluated by a veterinary pathologist using a scoring system. Expression of COX-1 and COX-2 was confirmed by use of immunoblotting analyses.

RESULTS

All specimens from healthy stomachs strongly expressed COX-1, whereas only 2 of 10 expressed COX-2. The expression of both isoforms varied greatly in the ulcerated mucosal specimens. Expression of COX-1 was significantly lower and expression of COX-2 was significantly higher in ulcerated versus healthy specimens.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased expression of COX-2 in gastric ulcers of the squamous portion of the stomach in horses suggested a role for this enzyme in gastric ulcer healing.

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.