In vitro effects of hydrochloric acid and various concentrations of acetic, propionic, butyric, or valeric acids on bioelectric properties of equine gastric squamous mucosa

Gastroscopic characterisation and prevalence of gastric ulcer syndrome in working mules in Colombia

BACKGROUND

The existing literature does not contain information about the prevalence of gastric ulcers in mules, and on the potential associations between the presence of ulcers and work load, work type, diet, sex, age and body condition score (BCS).

OBJECTIVE

To estimate the prevalence and factors associated with mule gastric ulcer syndrome (MGUS) and evaluate its distribution in both mule squamous gastric disease (MSGD) and mule glandular gastric disease (MGGD) mucosa in a population of mules in Colombia.

STUDY DESIGN

Observational, cross-sectional.

METHODS

A total of 97 clinically healthy mules of different ages and locations in the province of Antioquia (Colombia) were included in this study. The mules were involved in agricultural activities (i.e., riding, pack and ranch mules) at the time of the study. The animals underwent gastroscopic evaluation, and ulcer scores from 0 to 4 were assigned based on severity, with scores ≥2 indicating clinical relevance. The presence or absence of ulcer in the squamous and/or glandular region of the stomach was recorded. Data related to work type, work load and diet, as well as sex, age and BCS were recorded for each mule. Pearson's chi-square test was used to determine the association between the outcomes and explanatory variables of the study (p ≤ 0.05). The results of the risk estimations were presented as odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

The frequency of MGUS in the study population was 42%. Most of the lesions were located in the squamous region of the stomach (27%), mainly in the margo plicatus, and 20% were located in the glandular region, mainly in the fundus and pyloric antrum. Six animals showed lesions in both squamous and glandular regions. Work load was the only variable associated with the presence of MGUS (OR: 1.98; 95% CI: 0.49-0.96) and MSGD (OR: 1.78; 95% CI: 0.36-0.67). Nevertheless, the findings did not provide any significant risk assessment result, nor did they reveal any significant interactions among the other variables.

MAIN LIMITATIONS

This study used convenience sampling from a limited geographic region, and multivariate analysis was not performed, one of the exclusion criteria was the use of nonsteroidal anti-inflammatory drugs, which means that the effect of these drugs can no longer be evaluated.

CONCLUSIONS

MGUS occurs in mules subjected to agricultural work, the risk factors associated with EGUS do not appear to be significant in mules and other equids subjected to the same conditions, in this region. Further research is needed to define the differential dynamics of MGUS in comparison with the findings in horses.

The effect of feeding a commercial feedstuff on gastric squamous gastric disease (ESGD) healing and prevention of recurrence

Feedstuffs are often recommended to mitigate potential damage from acid associated with equine squamous gastric disease (ESGD). In acidic conditions, pectin alters its structure to one like mucus and binds the stomach mucosa, whilst alfalfa has a strong intrinsic acid buffering capacity. The study aimed to determine whether feeding a commercial beet pulp/alfalfa/oat fibre mix aids ESGD healing and/or prevention of recurrence. Ten adult horses with naturally occurring ESGD were included. All animals were treated with omeprazole as per the attending veterinarian's recommendation and randomly allocated to also be fed a commercial beet pulp/alfalfa/oat fibre mix (1Kg/horse divided into 2 meals/day; n=5) or no additional feed (n=5) for one month. Gastroscopy was then repeated to assess response to therapy. If the ESGD had healed, omeprazole therapy was discontinued, and the commercial feed given to all horses for a further month. Gastroscopy was repeated to determine ESGD recurrence. The mean (±SD) age of the horses was 11.6 (±3.8) years; 4 mares and 6 geldings; various breeds were represented; and the median (range) initial ESGD grade was 2 (2-4). ESGD had healed (grade 0/4) in all animals after one month. After a further month, ESGD had recurred in significantly (p=0.04) more animals that did not receive the commercial feed initially (3/5; 60%; mean [range] ESGD grade 3 [0,4]) compared to those that did (0/5; 0%; mean [range] ESGD grade 0 [0,0]). Thus, the commercial beet pulp/alfalfa/oat fibre mix aided prevention of ESGD recurrence when fed during the healing and prevention phases.

A Comparison of the Efficacy of Two Omeprazole Formulations in the Treatment of Equine Gastric Ulcer Syndrome in Racehorses: A Blinded, Randomized Clinical Trial

Equine gastric ulcer syndrome (EGUS) is the most common disease of the stomach in horses and treatment is based on the oral administration of omeprazole for at least 28 days. Aim of this study was to compare the efficacy of two formulations of oral omeprazole-powder paste and gastro-enteric resistant granules-in the treatment of naturally occurring gastric ulcers in racehorses. Thirty-two adult racehorses, aged between 2 and 10 years old, with clinical signs of EGUS were included in this blinded, randomized clinical trial. Two gastroscopies were performed to evaluate gastric lesions in the squamous or glandular mucosa before and after 28 days of treatment. After the first gastroscopy, 2/32 horses were excluded because affected by equine squamous gastric disease (ESGD) 1/4. The remaining horses were divided into 4 groups, and were treated with 2 formulations of omeprazole (gastroenteric resistant granules, group 1, or powder paste, group 3) or with 2 placebo formulations (granules, group 2, or paste, group 4). Treatments were performed in the placebo horses affected by ESGD or equine glandular gastric disease after the T28 gastroscopy control. No differences were found between groups at T0. Differences were found between T0 vs. T28 for granular (P = .002) and powder paste (P = .01) formulations. No differences were detected between the two groups receiving omeprazole formulations at T28 (0.34) and between T0 vs. T28 for either of the groups receiving placebo treatments. For all the variables, the size of the effect was greater than 0.5, proving that the treatments had a considerable effect. Gastro-enteric resistant granules and powder paste omeprazole showed similar efficacy in the treatment of ESGD. The glandular mucosa responded poorly to treatment with omeprazole.

Horse Grimace Scale Does Not Detect Pain in Horses with Equine Gastric Ulcer Syndrome

Equine gastric ulcer syndrome (EGUS) is a highly prevalent and presumptively painful condition, although the amount of pain horses might experience is currently unknown. The aims of this study were to determine if the Horse Grimace Scale (HGS) could identify pain behaviours in horses with and without EGUS and if severity would be positively associated with the HGS score. Horse grimace scale scores were assessed blindly using facial photographs by seven observers and involved evaluation of 6 facial action units as 0 (not present), 1 (moderately present) and 2 (obviously present). Lameness examination, serum amyloid A (SAA) measurement and gastroscopy evaluation were performed on all horses. Horses (n = 61) were divided into two and three groups based on the presence (yes, no) and severity (none, mild, moderate-severe) of EGUS, respectively. Presence of lameness and elevated SAA (≥50 µg/mL) were used as exclusion criteria. Inter-observer reliability was analyzed by intra-class correlation coefficients (ICC). HGS scores between groups were compared using Welch's and Brown Forsythe tests (p < 0.05). Overall, HGS ICC was "excellent" (0.75). No significant differences (p = 0.566) were observed in HGS scores between horses with and without gastric lesions (mean, 95% CI; 3.36, 2.76-3.95 and 3, 1.79-4.20, respectively). HGS was not influenced by the presence or severity of EGUS in this current study. Further studies investigating the use of different pain scales in horses with EGUS are needed.

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.

Determinación de Helicobacter spp. en mucosa gástrica glandular de mulas a través de la prueba de la actividad de la ureasa e histopatología

La información sobre la presentación y los factores predisponentes del síndrome de úlcera gástrica en mulas (SUGM) es escasa en comparación con el síndrome de úlcera gástrica en equinos (SUGE) y asnales. Debido a la naturaleza multifactorial de este síndrome, la helicobacteriosis ha sido estudiada en otras especies. El objetivo fue establecer la presencia de Helicobacter spp. en mucosa gástrica de mulas a través de la prueba rápida de la ureasa (PRU) y de análisis histopatológico. Menos del 27% de las muestras reaccionaron a la PRU, con tiempos prolongados de reacción, y al Agar Urea (prueba de oro), con menor porcentaje de positividad. La histopatología reveló procesos inflamatorios crónicos, sin presencia de bacterias curvoespiraladas. Las PRU no fueron conclusivas en la determinación de Helicobacter spp., comportamiento similar reportado en equinos. Se requieren exámenes diagnósticos específicos y procedimientos complementarios que explore regiones del estómago en consideración del número de muestras representativas.

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.

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.

High intake of sugars and starch, low number of meals and low roughage intake are associated with Equine Gastric Ulcer Syndrome in a Belgian cohort

Equine gastric ulcer syndrome (EGUS) is a pathological condition affecting the glandular and squamous regions of the stomach. It is characterized by non-specific clinical signs, behavioural changes or can also be found without any overt clinical manifestations. Nutritional factors such as intermittent feeding, high sugars and starch intake, large amounts of straw as forage and prolonged time without access to forage have all been associated with an increased risk of equine squamous gastric disease (ESGD). The aim of this study was to investigate which nutritional practices are commonly seen in clinical ESGD cases in Belgium. Medical records of 27 horses referred to the equine nutritional service at Ghent University (2013-2018) due to equine gastric ulcer lesions were reviewed. Twenty-one healthy horses referred for dietary evaluation during the same period were selected as control cases (CC). Dietary evaluation was performed on an individual basis. Forage/concentrate ratio on dry matter basis, forage content in the diet, total dietary sugars and starch intake per day and per meal were analysed. Retrospective descriptive and statistical analyses were performed. Significantly, higher amounts of forage intake (%DM per BW) in the CC vs. ESGD group were noted (p ≤ .05) with average values of 1.39 (SD ± 0.27) and 1.27 (SD ± 0.70) respectively. There were no significant differences for sugars and starch intake in g/kg BW/day (p = .18). However, the sugars and starch intake per meal (g/kg BW/meal) in the CC group (average value 1.06, SD ± 0.56) was significantly (p < .001) lower than in the EGUS group (average value 1.85 SD ± 0.78). Forage intake below the recommended absolute minimum value as well as high sugars and starch intake were most commonly associated with EGUS in the present case series. An adequate diet formulation taking into account these main nutritional factors is therefore essential to avoid gastric problems in horses.

Does prebiotic feeding affect equine gastric health? A study on the effects of prebiotic-induced gastric butyric acid production on mucosal integrity of the equine stomach

Fructo-oligosaccharides are commonly administered as prebiotics to horses in order to reduce the risk of disruption of microbial populations in the hindgut. Their microbial degradation to SCFA already begins in the stomach potentially resulting in increased gastric concentrations of SCFA such as butyric acid. The impact of butyric acid on the squamous mucosa is postulated to be detrimental, its effects on the glandular mucosa are yet unknown. Thus, the aim of this study was to determine the effects of butyric acid exposure on the functional integrity and morphology of the equine nonglandular and glandular gastric mucosa using butyric acid concentrations equivalent to the ones found in horses subjected to prebiotic fructo-oligosaccharides feeding. Gastric mucosal samples of healthy horses were exposed to butyric acid using the in vitro Ussing chamber technique. Electrophysiological parameters were continuously monitored, mucosal samples were blinded and histomorphological analysis was performed using a scoring system for assessment of histopathologic changes. Exposure to butyric acid resulted in pathohistomorphological changes in the glandular mucosa and in impairment of functional mucosal integrity in the squamous and the glandular mucosa as documented by significant changes in tissue conductances (G_t). Administration of fructo-oligosaccharides as a preventive prebiotic measure to horses should therefore be carefully considered, particularly in horses known to be at risk of developing EGUS.

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.

Therapeutics for Equine Gastric Ulcer Syndrome

Equine gastric ulcer syndrome (EGUS) is an umbrella term used to describe ulcers in the nonglandular squamous and glandular mucosa, terminal esophagus, and proximal duodenum. Gastric ulcers in the squamous and glandular regions occur more often than esophageal or duodenal ulcers and likely have a different pathogenesis. At present, omeprazole is accepted globally as the best pharmacologic therapy for both regions of the stomach; however, the addition of coating agents and synthetic prostaglandins could add to its effectiveness in treatment of EGUS. Dietary and environmental management are necessary for prevention of recurrence.

Effects of two alfalfa preparations with different particle sizes on the gastric mucosa in weanlings: alfalfa chaff versus alfalfa pellets

Background

Feeding alfalfa hay is often recommended for its buffering components, like protein and calcium, to prevent lesions of the gastric mucosa in horses. Until now, there has been no information regarding the influence of alfalfa particle size on the gastric mucosa. The aim of this study was to investigate the effects of feeding two alfalfa preparations with different particle sizes (alfalfa chaff vs alfalfa pellets) in comparison with grass hay on the gastric mucosa in weanling horses. We hypothesized that feeding a high proportion of fine alfalfa particles would negatively impact gastric mucosa and that feeding long alfalfa chaff would improve gastric mucosal health in weanlings.

Results

Before weaning, the prevalence of gastric mucosa lesions (one or more lesions considering all locations in the stomach) was 84.3 %; at 14 days after weaning, it was almost 100 %. Before and after weaning, most of the lesions were found at the greater curvature of the squamous mucosa and at the lesser curvature. After weaning, gastric mucosal lesions at the pylorus were significantly more severe in the group fed alfalfa chaff (p = 0.002). In the other regions, no differences related to the feeding regimes were observed.

Conclusions

Feeding alfalfa failed to improve gastric mucosal lesion scores in weanlings. Furthermore, foals fed alfalfa chaff had higher lesion scores at the pylorus. Alfalfa leaves contain a superior protein source and high amounts of calcium and magnesium, providing extra nutritional advantages in growing horses. At this time, either traditional grass hay rations or grass hay with alfalfa pellets can be recommended.

Pathology of gastric lesions in donkeys: A preliminary study

REASONS FOR PERFORMING STUDY

Donkeys (Equus africanus asinus) are important working animals, particularly in countries where the majority of the population lives below the poverty line. Gastric ulceration has been shown to be common in British donkeys but donkeys from other parts of the world have not been as extensively researched.

OBJECTIVES

This study was performed as a preliminary overview of the severity and distribution of gastric lesions in mature donkeys and to document which parasites were present.

STUDY DESIGN

Descriptive study of pathological findings.

METHODS

Stomachs of 35 mature draught donkeys were examined grossly and histopathology samples taken from 5 regions of the gastric mucosa.

RESULTS

Gross examination revealed hyperaemia, oedema, erosions and ulcers in addition to parasitic lesions. Histopathological examination revealed hyperkeratosis, acanthosis, vacuolar degeneration of stratified squamous cells, gastritis, erosions, ulcerations, scarring, hyperactivity of mucus glands, periglandular fibroplasia and parasitic granulomes with infestation by Gasterophilus spp. larvae, Habronema spp. and Draschia megastoma.

CONCLUSIONS

In donkeys, ulceration of the nonglandular regions of the stomach is more prominent than the glandular regions and parasitic infestations were frequent.

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.

Equine stomachs harbor an abundant and diverse mucosal microbiota

Little is known about the gastric mucosal microbiota in healthy horses, and its role in gastric disease has not been critically examined. The present study used a combination of 16S rRNA bacterial tag-encoded pyrosequencing (bTEFAP) and fluorescence in situ hybridization (FISH) to characterize the composition and spatial distribution of selected gastric mucosal microbiota of healthy horses. Biopsy specimens of the squamous, glandular, antral, and any ulcerated mucosa were obtained from 6 healthy horses by gastroscopy and from 3 horses immediately postmortem. Pyrosequencing was performed on biopsy specimens from 6 of the horses and yielded 53,920 reads in total, with 631 to 4,345 reads in each region per horse. The microbiome segregated into two distinct clusters comprised of horses that were stabled, fed hay, and sampled at postmortem (cluster 1) and horses that were pastured on grass, fed hay, and biopsied gastroscopically after a 12-h fast (cluster 2). The types of bacteria obtained from different anatomic regions clustered by horse rather than region. The dominant bacteria in cluster 1 were Firmicutes (>83% reads/sample), mainly Streptococcus spp., Lactobacillus spp. and, Sarcina spp. Cluster 2 was more diverse, with predominantly Proteobacteria, Bacteroidetes, and Firmicutes, consisting of Actinobacillus spp. Moraxella spp., Prevotella spp., and Porphyromonas spp. Helicobacter sp. sequences were not identified in any of 53,920 reads. FISH (n = 9) revealed bacteria throughout the stomach in close apposition to the mucosa, with significantly more Streptococcus spp. present in the glandular region of the stomach. The equine stomach harbors an abundant and diverse mucosal microbiota that varies by individual.

Amino acid profile during exercise and training in Standardbreds

The objective of this study is to assess the influence of acute exercise, training and intensified training on the plasma amino acid profile. In a 32-week longitudinal study using 10 Standardbred horses, training was divided into four phases, including a phase of intensified training for five horses. At the end of each phase, a standardized exercise test, SET, was performed. Plasma amino acid concentrations before and after each SET were measured. Training significantly reduced mean plasma aspartic acid concentration, whereas exercise significantly increased the plasma concentrations of alanine, taurine, methionine, leucine, tyrosine and phenylalanine and reduced the plasma concentrations of glycine, ornithine, glutamine, citrulline and serine. Normally and intensified trained horses differed not significantly. It is concluded that amino acids should not be regarded as limiting training performance in Standardbreds except for aspartic acid which is the most likely candidate for supplementation.

Pathology of gastritis and gastric ulceration in the horse. Part 1: range of lesions present in 21 mature individuals

REASONS FOR PERFORMING STUDY

Gastric ulceration is now widely recognised as an important disease in high performance horses. Little is known about gastric histopathology in healthy or diseased animals; a comprehensive assessment would enhance interpretation of gross findings through assessment of their accuracy and allow for identification of lesion variety and pathogenesis in different anatomical regions of the stomach.

OBJECTIVES

To investigate the true extent and variety of gastric lesions in a mixed population of mature horses at post mortem.

METHODS

Stomachs were removed from a mixed population of 21 horses at post mortem. Mucosal abnormalities were recorded in photographic and written form. Representative samples from all gross lesions were taken for histopathology and processed routinely. Special stains including Gram, PAS and Warthin Starry, were used when appropriate. Pathological classification of lesion type using both gross and histological appearances was performed.

RESULTS

Classification of lesions within the squamous region included hyperkeratosis, punctate scars, diffuse erosions/ ulcerations and margo injuria; and within the glandular region, hyperaemia, focal erosions and ulcerations. Glandular metaplasia was recognised for the first time in the equine stomach. No Helicobacter-like organisms were detected in association with lesion development.

CONCLUSIONS AND POTENTIAL RELEVANCE

This study used gross and histological examination to highlight the large variety of naturally occurring gastric lesions in a mixed population of horses. Analysis of the pathogenesis of lesion development is now possible. Further research regarding the range of pathology in larger, more diverse groups of horses is required.

In vitro effects of hydrochloric and lactic acids on bioelectric properties of equine gastric squamous mucosa

REASONS FOR PERFORMING STUDY

Volatile fatty acids, byproducts of carbohydrate fermentation by resident bacteria, have been implicated in causing nonglandular (NG) gastric ulcers. Lactic acid (LA), also produced by stomach bacteria, may cause gastric ulcers when exposed to the equine NG mucosa.

OBJECTIVES

To investigate the in vitro effects of LA on equine NG mucosa bioelectric properties, sodium transport and tissue resistance.

METHODS

Gastric tissues obtained from 13 mature horses were studied in Ussing chambers. Short-circuit current (Isc) and potential difference (PD) were measured, and electrical resistance (R) and conductance (G) calculated for tissues after addition of HCl and LA (5, 10, 20 and 40 mmol/l) in normal Ringer's solution (NRS).

RESULTS

Mucosa exposed to HCl or LA (5, 10 and 20 mmol/l) in NRS (pH 1.5 and to a lesser extent pH 4.0) had a significant decrease in Isc and PD. Mucosa exposed to a high concentration of LA (40 mmol/l) in NRS (LRS) at pH 1.5 showed an increased G, but this increase was not significant. Values returned to baseline after solutions were returned to pH 7.0. Histological changes were consistent with HCl-induced (pH <4.0) acid damage.

CONCLUSIONS

HCl induced alteration in bioelectric properties of equine NG mucosa whereas addition of LRS did not, other than those changes seen with HCl alone.