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EQUINE VETERINARY EDUCATION / AE / OCTOBER 2014


TABLE 1: Grading system for the squamous and glandular mucosa. Adapted from Andrews et al. (1999) Squamous mucosa


Grade 0 Grade 1


Grade 2 Grade 3


Grade 4


The epithelium is intact and there is no appearance of hyperkeratosis (yellowing of the mucosa)


The mucosa is intact but there are areas of hyperkeratosis


Small, single, or multifocal (<5) superficial lesions


Large single deep, or multiple (≥5) focal superficial lesions


Extensive lesions with areas of apparent deep ulceration


the level of the pylorus is reached the gastroscope is turned sharply to the left, pushing it into the duodenum. As soon as the duodenum is entered it is, somewhat counter intuitively, necessary to withdraw the gastroscope slightly to allow inspection of the duodenum. Once the examination of the stomach (± duodenum) has been completed the scope is then simply withdrawn. Removal of the air from the stomach by suction at the completion of the procedure is a matter of operator preference, although anecdotally it seems to be more important in foals than mature horses as they appear to be at increased risk of colic when the air is not removed. A complete examination of the stomach is important and


the presence/absence of squamous ulceration cannot be used as a predictor for the presence/absence of glandular ulceration (Murray et al. 2001; Begg and O’Sullivan 2003; Luthersson et al. 2009a). Observation of the squamous mucosa is relatively easy, whereas passage through to the pyloric antrum is more technically demanding. However, observation of the pyloric antrum is critical, as the majority of glandular ulceration occurs in this region (Murray et al. 2001; Luthersson et al. 2009a; Habershon-Butcher et al. 2012; Sykes et al. 2014a,b,c). Observation of the most ventral portion of the fundus is typically not possible due to the presence of fluid. The fluid can be suctioned out via the biopsy channel of the gastroscope; however, this is usually not necessary as ulceration in this region is rare (Luthersson et al. 2009a; Hepburn 2012). The squamous and glandular mucosa should be scored


separately. A variety of scoring systems have been described but, for simplicity, the authors prefer the system first described by the EGUS Council (Andrews et al. 1999), shown in Table 1 for the squamous mucosa. Currently, the authors use a similar scoring system for the glandular mucosa (Table 1) but it is recognised that the grading of lesions in the glandular mucosa along a linear scale of severity may not be appropriate. The correlation between clinical signs and lesion grade is inconsistent, with some horses demonstrating clinical improvement with the treatment of mild lesions, whilst others appearing unchanged despite gastroscopic resolution of severe lesions. The authors believe that care should be taken in over interpreting mild changes such as hyperaemia of the glandular mucosa and the presence of thickened rugal folds with the authors only assigning clinical significance to lesions of the glandular mucosa that appear to have disruption to mucosal integrity. Although not commonly performed by the authors, biopsy may be useful in such cases to assess the integrity of the mucosa. Similarly, the authors believe that caution should be exercised in over interpreting mild grade 2 lesions of the squamous mucosa as many are inconsequential


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Glandular mucosa


The epithelium is intact and there is no evidence of hyperaemia


The mucosa is intact but there are areas of hyperaemia


Small, single or multifocal (<5) superficial lesions


Large single deep or multiple (≥5) focal superficial lesions


Extensive lesions with areas of apparent deep ulceration


findings. Where the results of gastroscopy are equivocal, other differential diagnoses should be considered and/or a therapeutic trial considered.


Therapeutic trials The use of a therapeutic trial is logical when gastroscopy is not readily available and a positive response to treatment increases the index of suspicion of EGUS. Likewise, a positive response to treatment supports the clinical significance of mild lesions if the results of gastroscopy are equivocal. Importantly, in animals where gastroscopy has not been performed, a positive response to a therapeutic trial does not differentiate between ESGUS and EGGUS and, as such, in the authors’ opinion, a positive response to treatment should be viewed as a clear indication for gastroscopy in order to obtain a definitive diagnosis and to determine the affected region. Where funds are limited, treatment with omeprazole for 28 days may be initiated; however, gastroscopy is recommended prior to the discontinuation of therapy as the expected healing rate of EGGUS in this time is substantially lower than that of ESGUS (Sykes et al. 2014a,b,c). A negative response to trial therapy with omeprazole reduces the likelihood of EGUS, but does not completely discount it, as some animals are slow to respond clinically and clinical signs may not completely resolve until healing has occurred, especially with EGGUS. As such, in light of a negative response to omeprazole, other more likely differential diagnoses should be discounted first, but gastroscopy remains indicated if no specific diagnosis is made.


Faecal occult blood and sucrose permeability testing Testing for faecal occult blood is appealing due to its ease of use, simplicity and low cost. Recently the diagnostic accuracy of a commercial faecal blood test against gastroscopy has been tested in a population of Thoroughbred racehorses with the test performing poorly (Sykes et al. 2014d). A very high prevalence of faecal acidosis has previously been reported in this population (Sykes et al. 2013), and whether this affects test performance is not known. However, until further validated in the peer reviewed literature, the authors do not recommend the use of faecal occult blood testing as a diagnostic test for EGUS.


Similarly, use of the sucrose permeability test is appealing


for its ease of use and it has been proposed as a screening test for EGUS (O’Conner et al. 2004; Hewetson et al. 2006). Recently a method of reliably measuring serum sucrose has been validated and pilot data on the use of the test in clinical patients are encouraging (Hewetson et al. 2014). However, at


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