Primary gastric impaction is an uncommon condition. Furthermore, the factors associated with gastric impaction and the optimal method of treatment are not clear. The aim of this article is to describe the clinical findings, treatment and outcome of horses with a primary gastric impaction. Medical records of horses that presented with a primary gastric impaction between 2005 and 2008 were reviewed and 20 horses with a primary gastric impaction identified. Diagnosis of a primary gastric impaction was made if the horse had been fasted for a minimum of 16 h, a concretion of ingesta precluded visualisation of the margo plicatus and there was no evidence of concurrent intestinal pathology. Thirteen of 20 (65%) horses were presented on an emergency basis. The most common complaint was inappetence (50%) followed by acute colic (35%) and recurrent colic (35%). On initial examination for colic, all horses had a normal heart rate and 7 of 20 (35%) had decreased gastrointestinal borborygmi. All horses were treated with enteral fluid therapy. The median dose of fluids administered per day was 5 doses (range 1–8 doses) of 2–10 l of isotonic electrolyte solution. The median length of treatment until resolution was 2 days (range 1–5 days). Eighteen of 20 (90%) horses survived to discharge. Primary gastric impaction appears to be a condition with clinical signs of inappetence and mild abdominal discomfort. This is the largest group of horses reported that were treated with enteral fluid therapy for a gastric impaction and it was concluded that enteral fluid therapy was of value in this study.