Success of treatment comparing two omeprazole preparations for Equine Gastric Ulcer Syndrome (EGUS)

Equine Gastric Ulcer Syndrome (EGUS) is a common problem in equine athletes. The ECEIM consensus statement and the manufacturers recommend omeprazole at a dosage of 2-4 mg/kg PO SID (buffered formulations) or 1-2 mg/kg PO SID (enteric coated granules) for the treatment of ESGD (Equine Squamous Gastric Disease) and the same dosages in combination with sucralfate (12 mg/kg PO BID) for EGGD (Equine Glandular Gastric Disease). In this study, the two formulations were compared in an equine hospital setting. A modified clinical scoring was used to include 87 horses (January 2019-December 2020) presented for recurrent colic, weight loss, exercise insufficiency or typical behavior (bruxism, groaning), in which gastroscopy was performed. Horses were classified as 0-4 for ESGD (consensus statement) and 0-3 for EGGD (modified from non-remarkable/mild/moderate/severe findings according to the Consensus statement) by the veterinarian performing the gastroscopy and led to the recommendation of therapy in 63 cases. Omeprazole therapy (buffered formulation 4 mg/kg PO SID, GastroGard (TM), Boehringer Ingelheim or enteric coated granules 2 mg/kg PO SID, Equizol (TM), CP Pharma), in case of EGGD combined with sucralfate (12 mg/kg PO BID, Sucrabest (TM), Combustin) was recommended in combination with improvements concerning housing, feeding and reduction of stress according to the ECEIM consensus statement. Gastroscopy was repeated about 4 weeks later in 23 horses. Standing images were randomized and scored twice by two blinded, experienced observers (ECEIM diplomats), so that 4 scorings for both time-points were available of ESGD and EGGD. The mean values of these scorings were the basis for the evaluation of treatment success. Additionally, inter- and intra-observer agreement were compared for ESGD and EGGD. Both formulations were highly effective in improving ESGD by >= 2 subgrades or by achieving grade 0 in 93 % and 100 % of horses treated with buffered (n = 15 GastroGard (TM)) and encapsulated formulations (n = 8, Equizol (TM)), respectively. EGGD was improved by >= 1 subgrade or achieving grade 0 in 64 % and 71 % of horses treated with bufferedand enteric coated formulations combined with sucralfate, respectively. No significant differences between the two formulations were found for either ESGD or EGGD (P > 0.999). Inter- and intra-observer-agreement were excellent for ESGD (kappa = 0.832-0.975), while the inter-observer agreement for EGGD was found to be fair (kappa = 0,390). In conclusion, both omeprazole formulations can be recommended for the treatment of EGUS, in particular ESGD. Differences in long-term effect and recurrence rates should be studied in future studies.