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EQUINE VETERINARY EDUCATION / AE / OCTOBER 2014


tightening of the girth (Murray et al. 1989; Murray 2009; Hepburn 2012). Attempts to correlate clinical signs with ulcer severity at a population level have been largely unrewarding, but this should not lead to the conclusion that EGUS is clinically insignificant at the individual horse level when clinical signs are present. Similarly, many horses with gastroscopic evidence of EGUS display no apparent clinical signs and this is commonly used as a reason to dismiss the clinical significance of EGUS. However, the authors have observed that many supposedly ‘asymptomatic’ horses change behaviour, or have an improvement in their appetite and/or performance, in response to treatment, suggesting that subclinical disease may be common. Considering this, the authors believe that EGUS should be


considered as a differential diagnosis in any horse demonstrating vague clinical signs potentially referable to gastrointestinal discomfort. Importantly, the prevalence of ESGUS, and thus risk of associated clinical signs, increases with increasing intensity of exercise and management, while, in contrast, the prevalence of EGGUS, and thus risk of associated clinical signs, appear largely independent of use (Luthersson et al. 2009b). As such, EGGUS should be considered as a differential diagnosis in any case demonstrating compatible clinical signs, regardless of usage type. In such cases, it is equally important that other differential diagnoses be considered and the response to treatment followed. Lastly, although the link between colic and EGUS is controversial, the authors believe that EGUS should be considered as a differential diagnosis in all cases of idiopathic colic, especially in recurrent cases.


Diagnosis


A variety of methods including gastroscopy, the response to therapeutic trials, faecal occult blood and sucrose permeability testing are used, or have been proposed, as means of diagnosing gastric ulceration in the horse and thus warrant discussion.


Gastroscopy In the authors’ opinion gastroscopy remains the only accurate way to diagnose EGUS ante mortem. In addition to confirming the presence or absence of EGUS, it allows further distinction into whether the squamous mucosa, glandular mucosa or both are affected as well as allowing determination of the severity of the lesions. It is important to distinguish whether the squamous mucosa, glandular mucosa or both are affected as this has implications with regards to the agents used for treatment and the expected duration of treatment required. Furthermore, this allows exclusion of other diseases that may mimic the clinical signs of EGUS, such as gastric impaction (Vainio et al. 2011). Historically, gastroscopy has been the domain of referral


centres but the advent of smaller, portable units, and their increased affordability, has increased the availability to ambulatory veterinarians and those in smaller facilities. A range of scope sizes is available. The authors both use and recommend a scope with an insertion length of at least 3m and an outer diameter of approximately 12.8 mm. Although used in the past, and often cited in the older literature, gastroscopes <3m long are insufficient in length to allow examination of the entire stomach in larger breed horses. In particular, observation of the pyloric antrum is often not


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possible when using shorter gastroscopes, which, given that the majority of glandular disease occurs in this region (Begg and O’Sullivan 2003; Luthersson et al. 2009a; Tamzali et al. 2011), is essential. Similarly, while gastroscopes with a narrower outer diameter may have some advantages, namely the ability to examine smaller patients, the authors have found the gastroscopes <12.8mm in diameter are too flexible, making entry into the pylorus difficult, if not impossible, in many animals. Consequently a complete examination of the stomach is often not accomplished. In the authors’ experience, although the diameter of 12.8mm may preclude the examination of some smaller pony breeds, the vast majority of horses and many larger pony breeds can readily be examined with a gastroscope of that size. Case preparation is important. The presence of even a


small amount of residual food can impair visibility and make entry into the pyloric antrum difficult. In the authors’ experience the duration of fasting is dependent on the horse’s use and its diet. For sport and pleasure horses eating a standard, hay based diet, a minimum of 16 h of fasting is required to ensure complete emptying of the stomach. In contrast, the duration of fasting for Thoroughbred racehorses on high grain/low roughage diets appears much shorter with as little as 6–8 h required for complete gastric emptying (Sykes et al. 2014b). In practice, the owner/trainer is instructed to feed the horse their normal grain meal but only a small amount of hay (typically a single flake/biscuit) the evening before and to remove any remaining feed first thing in the morning upon arriving at the stables. The owner/trainer is then instructed to train the horse as per normal (if desired) and the gastroscopy examination is performed later that morning with the horse fed its morning feed after awaking from sedation. The authors have found that this approach significantly improves owner/trainer compliance and willingness to examine horses as, in effect, the horse does not skip a meal and the impact on its training is minimal. Removal of water one hour prior to examination is advantageous but not mandatory. Given the rapidity with which the horse empties fluid from its stomach, longer durations of water deprivation are unlikely to offer any advantage. The technique of gastroscopic examination is relatively straightforward, although some patience and practice is required to achieve a complete examination of the stomach consistently. The authors use a 19mm outer diameter × 80 cm long lightweight vinyl tube purchased from a local hardware store to protect the gastroscope and prevent retroflexion in the pharynx. Additionally, the use of such a tube appears to improve patient compliance with less agitation observed during passage of the gastroscope. Following appropriate sedation, the tube is preplaced and secured to the halter, extending from the rostral nares to approximately 15 cm into the oesophagus. The (well lubricated) gastroscope is then passed through the tube to a length of approximately 2m until the stomach is entered. A variety of options can be used for insufflation but the authors prefer a 15 l pressure sprayer purchased from the local hardware store. The sprayer is prepressurised prior to sedation of the horse and a second sprayer is kept as a spare in the event of eructation. Once the stomach is entered the hose of the sprayer is attached to the biopsy channel of the scope and the air is injected into the stomach. Good insufflation of the stomach is essential for a thorough examination, and the authors have not observed any deleterious effects of ‘excessive’


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