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Veterinary sciences
UDC: 6169:616.3:636.1
Stefanyk O. V.
PhD student Slivinska L. G.
DVM, Proffesor Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies Pekarska Str., 50, Lviv, 79010, Ukraine DOI: 10.24412/2520-6990-2022-22145-3-7 PREVALENCE OF EQUINE GASTRIC ULCER SYNDROME IN POPULATION OF TORI AND
HUCUL HORSE IN WESTERN UKRAINE
Abstract
Equine gastric ulcer syndrome (EGUS) is a very common disease among horses with the highest prevalence in performance horses. The objectives of this study were to investigate the prevalence and severity of EGUS in the population of n=22 horses presented with two breeds Tori and Hucul horse. The prevalence and severity of EGUS have been studied depending on workload management in this study horses, using for riding lessons and driving using drawn equipment suitable for horses. The gastroscopy was performed on two stables located in the Western region of Ukraine during the spring-autumn period of2020. Stomachs were evaluated using a 3-m long endoscope to assess the squamous and glandular mucosa of each horse. Gastric ulcers were evaluated using a 0-4 grading system. In this study, due to the contrast between the physiology and etiopathogenesis of gastric mucosa, stomach lesions were divided into squamous (ESGD) and glandular (EGGD) gastric diseases. This study shows the overall prevalence of EGUS in 27.2% of examined horses. Squamous gastric ulcers were diagnosed in all horses with EGUS, unlike glandular lesions. In this study, gastric lesions were presented with severity scores ranging from 1 to 3 whereas lesions grade 2 were observed in most horses with EGUS. Both squamous and glandular lesions were diagnosed in 9% of horses. The presented study conclude that EGUS in this particular population of horses, not in a race and intensive training, was relatively low prevalent within the squamous and glandular mucosa. Also, low difference was found between the group of riding lesson and driving horses, besides we did notfind clear association between sex and age in horses with EGUS.
Key words: EGUS, ESGD, EGGD, horse, stomach, ulcer, prevalence.
Introduction
In veterinary clinical practice, stomach diseases in horses is highly prevalent. Most often they appear as erosive and ulcerative adhesions of gastric mucosa and may vary depending on the severity and numbers of lesions. Equine gastric ulcer syndrome (EGUS) is a term used to describe the complicated and multifactorial nature of erosive and ulcerative diseases of the gastric mucosa, as well as the use of the term peptic ulcer disease (PUD) in man [18]. Two terms: Equine squamous gastric disease (ESGD) and Equine glandular gastric disease (EGGD) are used to describe gastric mucosal defects according to anatomical features of the stomach.
EGUS is a common problem in horses and foals, which may negatively affect their health and performance. Although the aetiology of this disease is not known well, risk factors like: active training, feeding management, housing and stall confinement, administration of non-steroidal anti-inflammatory drugs (NSAID), gender, temperament, and transportation is thought to be associated with EGUS [11,12,15,16].
Pathophysiologically imbalance between mucosal aggressive factors (increased acid content) and protective factors (mucus and bicarbonate) have been implicated as causative mechanisms for gastric ulcer disease in horses [7].
Diagnosis of EGUS requires a thorough history and physical examination. However, gastroscopy is the most effective diagnostic method currently available.
This study therefore aimed to investigate the prevalence, anatomical distribution and severity of gastric ulceration in population of Tori and Hucul horse in Western region of Ukraine.
The Hucul or Carpathian is a small
horse breed originally from the Carpathian Mountains. It has a heavy build and possesses great endurance and hardiness. Hucul horse are usually calm with a good disposition, and are used for both hacking and pulling timber in otherwise inaccessible forested areas.
By nature, the Tori horse is energetic, good-natured, docile and is a willing animal. The Tori horse was wide-rangingly crossed with Hannoverians, English Thoroughbreds, and other sporty breeds. In 2008, the Tori studbook that is held by the Estonian Horse Breeders' Association (Et: Eesti Hobusekasvatajate Selts) was split into two sections; TA and TB, the heavier Toris went into TA and the lighter ones into TB.
Material and Methods
The study was conducted on two stables in Western region of Ukraine during summer-autumn period of 2020.
Examinations were performed with a 3m endoscope Surevision VLS- 150D Digital Video system. Before examination, all horses were fasted for 12-16 hours prior to endoscopy, and water was withheld for 5 hours before the procedure. Horses were sedated with xylazine (0.5-0.7 mg/kg, IV) or detomidine (0.11
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mg/kg, IV) and acepromazine (0.02 mg/kg, IV). During gastroscopy procedure, the stomach was insufflated with air to allow a visualise of entire stomach regions. As the endoscope enters the stomach, all anatomical features were evaluated for ulcerative changes on the gastric mucosa. Some stomach wall areas covered by remains of food were flushed by water to exclude presence of mucosal changes. In 3 horses, the pylorus was unable to be visualized because of the presence of residual feeding material. Gastric mucosal changes were scored by the 0-4 EGUS council grading system [18]. Grade 0: The epithelium is intact and there is no appearance of hyperkeratosis, grade 1: the mucosa is intact, but there are areas of hyperkeratosis, grade 2: small, single, or multifocal lesions, grade 3: large single or extensive superficial lesions, grade 4: extensive lesions with areas of apparent deep ulcerations. Glandular mucosa within anatomical regions: cardia, fundus, antrum and pylorus were evaluated and differentiated between hyperemic, hemorrhagic, fibrinosuppurative, ulcerated; depressed, flat, and rised mucosal changes.
A total of n= 22 horses were selected for this study. The criteria for this were healthy horses older than 2 y.o., without treatment by anti-ulcers medications for last 2 months. Information including age, gender, dietary management was obtained for each horse. The age difference in the studied horses ranged from 2 - 15 years (mean 7.4 ± 2.8). N= 10 horses were 2 - 5 years, n= 12 horses were 6 - 15 years old. There were 13 mares, 4 stallions and 5 geldings including n= 16 Tori and n= 6 Hucul horse. According to Tori studbook that is held by the Estonian Horse Breeders Association (Et: Eesti Hobusekasvatajate Selts) Tori horse breed is devided into two sections: TA (heavy Tori) and TB (light Tori) [4]. In this study Tori horses take the place of two types: the heavy (old) Tori horse n= 8 and the light Tori horse n= 8 were included in this study.
In present study, selected horses were represented by various types of workload, whereas n= 8 light Tori were used for riding lessons 2 - 3 times a day, 4 - 5 times a week in a controlled environment with limited riding and trail riding. Another horses including n= 6 Hucul and n= 4 heavy Tori horse were used in driving
either using drawn equipment suitable for horse Drawn
- Farming in agriculture sector, rest n= 4 heavy Tori were used in the carriage recreational riding in a city, 2
- 3 times a week each carriage.
Horses were fed grass hay and grain diets, with access to water. Medical history was obtained and included: administration of NSAIDs or anti - ulcer medications (omeprazole, misoprostol, sucralfate, H2 antagonists). Two horses with previous illness history had received NSAID over the sourse of days and none of the examinated animals received any anti-ulcer medication.
All manipulations with animals were carried out in accordance with the European Convention for the Protection of Vertebrate Animals, used for Experimental and Scientific Purposes (Strasbourg, 1986).
Results
A population of n= 22 horses were included in this study and considered for gastroscopic examination. Withholding feeding material before gastroscopy allowed the entire squamous gastric region lining to be seen in all horses. In 13.6% of horses, no glandular mucosa was observed due to obscured ventral portions of the stomach caused by leftover feeding materials and gastric secretion.
The overall prevalence of EGUS in all examined horses was 27.2%, most of them were mares 30.7% and horses 5 - 16 years old age group - 33.3%. Squamous gastric ulcers were diagnosed in all horses with EGUS, unlike glandular lesions. However, both squamous and glandular lesions were detected in 9% of horses with EGUS. Gastric lesions were presented with severity scores ranging from 1 to 3, whereas grade 4 lesion was not observed. Squamous mucosal defects with signs of hyperkeratosis were diagnosed in 4.5% of horses. In the majority, squamous gastric ulcers grade 2 were diagnosed in 13.6% of horses and 9% had ulcers grade 3. Squamous gastric lesions usually appeared on the stomach wall near margo plicatus border and glandular lesions seem to be located in pylorus and antrum region as focal hyperemia.
Table 1.
Severity of equine gastric ulcer disease by use and breed of horses based on the 0-4 grade system (EGUS __council grading system)._
Ulcer severity g rade
Use 0 1 2 3 4
Lesson horses 6 1 1 0 0
Driving horses 10 0 2 2 0
Breed - - - - -
Heavy Tori horse 6 1 1 0 0
Light Tori horse 6 0 1 1 0
Hucul horse 4 0 1 1 0
Total 16 1 3 2 0
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According to various workload management between horses, EGUS was diagnosed in 25% of riding lesson horses with 12.5% grade 1 as well as grade 2 lesions. All lesions were related to the squamous region of this grove.
EGUS in driving horses was observed in 28.5% of animals. In carriage recreational riding horses squa-mous lesion grade 3 was observed in 1/4 horse without lesions grade 1 - 2 and 4. In a Drawn - Farming horses squamous lesions grade 2 - 3 appeared in 3/10 horses. Both squamous and glandular lesions were presented in 2/10 horses of this grove.
In this study EGUS prevalence based on the horse breed was established in 33.3% of Hucul horse and 25% of Tori horse. Both squamous lesion grade 2 and hyperemia of glandular mucosa of the stomach were presented in 1/8 heavy Tori horse and 1/6 Hucul horse.
In this study, EGUS was seen in 30.7% of females, 20% of geldings, and 25% of stallions. The distribution of EGUS by age noticed 33.3% gastric lesions in 6 - 15 years old group of horses and 20 % in 2 - 5 years old (Table 1).
Discussion
The length of the fasting before the gastroscopy procedure was adequate to make both anatomical portions of the stomach to be visible in 19/22 horses. Gas-troscopy is the most sufficient method of EGUS diagnosis which allows to characterize the extent and severity of gastric lesions in horses by using a grading system [18]. In the current study horses with EGUS were scored by the 0-4 EGUS council grading system and had a severity grade 1 - 3 with most squamous lesions grade 2 presented in 18.1% of horses respectively.
This study shows that EGUS in the majority appeared on the squamous mucosa of the stomach unlike glandular. The results of other studies also confirm that gastric lesions are more likely to occur on the squamous mucosa than glandular [13,19] In accordance with foreign authors gastric ulcers most commonly affect squamous mucosa along the margo plicatus of the lesser curvature [13,16]. Similarly, this study shows that squamous lesions have occurred near margo plicatus with an overall prevalence of 27.2%. Both squamous lesions and glandular stomach hyperaemia were diagnosed in 9% of a 6 - 15 years old group of horses. Most often glandular mucosa ulceration occurs in combination with ESGD [3]. Association between localization and severity has also been described, whereas squa-mous lesions in area of margo plicatus are more severe and pylorus lesions of the glandular mucosa are more common [1,13]. Similarly, glandular hyperaemia appears in this study horses as blushing of the rugal folds of the pylorus. However, the reported prevalence of EGGD is higher and ranges between 13 - 51% compared to 9% in this study population [13,23]. The risk factors for EGGD have been poorly described. Although, there is an opinion about negative effect of different management strategies like feeding and exercise in the etiopathogenesis of EGGD. Pathogenesis and risk factors reported for EGGD are different from ESGD whereas high-intensity exercise show more clear
association with squamous lesions, in contrast to glandular where risk factors are not clear and more variable between populations. It has been suggested that management changes are imposed upon horses with the commencement of training, which can increase the risk factors for ESGD [23]. Recently it has been highlighted that exercise is associated with acid exposure in the squamous region of the stomach through acid reflux [12]. It also may have a significant effect on the nonglandular stomach.
This study found a low range of breed specific prevalence with 33.3% of Hucul affected horses and 25% of Tori horses with no difference between heavy and light Tori types. However, breed itself was not identified as a risk factor for EGUS [9]. In contrast, a postmortem study of 3,715 horses found to be EGUS more prevalent in Thoroughbred and Standardbred breeds than in cold-blooded horses [16]. It has been confirmed that the workload management and use of horses for competition, racing etc. is more evident risk factor for squamous lesions developing [2]. Gastric ulcers are often diagnosed in mentioned breeds due to the active training and high performance which is a confirmed risk factor for EGUS and as the intensity of training increases, the prevalence and severity of gastric ulcers growth [13,18,21,22]. In a previous study, we have shown that EGUS is a common disease in Thoroughbred and Ukrainian riding horse whereas gastric ulceration occurred in 35,7 - 50% of population horses depending on the training intensity between two periods of examination [17]. High EGUS prevalence was shown in endurance horses whereas gastric ulceration occurred in 93% and in 37% of untrained racehorses increasing to 80-100% within 2-3 months of race training [17,18,21,22].
This study find no associations between groups based on the use and physical activity. Gastric ulceration was present in 25% of examined lesson horses, and this is consistent with a prevalence 28.5% in driving horses in this study population. Analysis of the published researches did not show reports about the EGUS in a specific breed like Hucul and Tori horse used for a drawn power for different operations. Most of them report high EGUS prevalence in performance racehorses whereas a low number of studies have been performed on various horse breeds with different workload management.
In the current study prevalence of squamous gastric ulcers in light Tori horses involved in riding lessons was 25 % with no glandular lesions. In another study, ESGD was found to be less prevalent in 11% of university riding programme horses [8]. As author mentioned that low prevalence could be related to the fact that these study horses were not exposed to environmental and diet changes. According to published data, ESGD was found to be far more prevalent and severe in endurance horses in up to 93% of affected horses this has been correlated with the type of training due to the competitive elements [21]. However, several studies report about EGUS prevalence in 53% of pleasure, 35% of riding, and 49% of leisure horses with minimal physical activity [1,3,24].
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This study did not find any association between horses of two age groups. However, lesions of the squamous and glandular mucosa were shown in older horses of the 6-15 year old group. Similarly, a clinical study found a significant difference in older horses which were more likely to have both glandular and squamous ulcers [10]. Another author did not find clear association between age and sex in horses which were impacted by physical activity [5]. The same result has been revealed by another paper with no significant effect of age and sex in Thoroughbred horses with ESGD [22]. However, some studies suggest that number of lesions and ulcer severity may increase with age [13,15].
In this study horses were taken out to pasture, with a total time of 4-5 hours per day spent outdoors with access to grazing. It is thought that horses grazing at pasture have lower evidence through the continuous saliva secretion as a buffer stomach acid. In one study the effect of paddock versus stall housing on gastric pH was not evident [6].
It is important to note that EGUS in horses may show mild clinical signs [14]. Clinical signs associated with EGUS are numerous and may include symptoms like poor appetite, weight loss, decreased performance, diarrhanea, and acute or recurrent colic. Some horses commonly show abdominal pain and poor general appetite with presence of behavioral changes [14]. However, we did not record any clinical signs, all horses appear to be clinically healthy.
In conclusion, in this particular population of horses, not in race and intensive training, there was a relatively low prevalence of EGUS within the squamous and glandular mucosa. Also, low difference was found between the group of a riding lesson and driving horses, besides we did not find a clear association between sex and age in horses with EGUS. There is a little number of studies reported about EGUS prevalence in other breeds of horses with different workload management.
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