Effect of moving from being extensively managed out in pasture into training on the incidence of equine gastric ulcer syndrome in Icelandic horses.

Objective: To investigate equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD) in Icelandic horses moving from pasture into training.

Animals: 81 horses (median age, 3 years; interquartile range, 1 year) from 10 farms representing 4 different Icelandic regions.

Procedures: Initial gastroscopy was undertaken within 2 weeks of moving from pasture into a training establishment. A total of 71 horses underwent endoscopic examination again 8 weeks later. Various management and behavioral factors were assessed through face-to-face questionnaires with the owners or trainers. Multivariable logistic regression was used to determine factors contributing to any change in ESGD and EGGD severity score during the 8-week training period.

Results: Incidence of EGGD and ESGD in this feral population was similar to that found in domesticated horses. ESGD incidence (severity score, ≥ 2; score range, 0 to 4) reduced from an initial 71.6% (58/81) to 25.4% (18/71). On multivariable analysis, sex (ie, being a stallion or a female vs gelding) increased the likelihood of ulcer grade reduction. Being fed preserved forage 3 or more times a day also improved the likelihood of ESGD reduction (odds ratio, 17.95; 95% CI, 1.67 to 193.40; P = .017). Overall, the farm explained 35% of the variance, confirming the importance of management factors. Incidence of EGGD (severity score, ≥ 1; score range, 0 to 2) reduced from 47% (38/81) to 40.8% (29/71) during the same period. No measured variables were associated significantly with EGGD incidence or reduction.

Clinical Relevance: Pasture provision (without supplementary feed or forage) does not result automatically in a low incidence of gastric ulcers. Regular provision of preserved forage is a key factor in reducing ESGD incidence.