Gastrointestinal ultrasonography of normal Standardbred neonates and frequency of asymptomatic intussusceptions.

Background: Ultrasonographic appearance of the gastrointestinal (GI) tract of equine neonates has not been completely described.

Objectives: To describe (1) sonographic characteristics of the GI segments in normal nonsedated equine neonates, (2) intra- and interobserver variation in wall thickness, and (3) the sonographic appearance of asymptomatic intussusceptions, and (4) to compare age and sonographic findings of foals with and without asymptomatic intussusceptions.

Animals: Eighteen healthy Standardbred foals ≤5 days of age.

Methods: Prospective, cross-sectional blinded study. Gastrointestinal sonograms were performed stall-side. Intraobserver variability in wall thickness measurements was determined by calculating the coefficient of variation (CV). The Bland-Altman method was used to assess interobserver bias. Student's t-test and Fisher's exact test were used to test the association among presence of intussusceptions, age, and selected sonographic findings.

Results: The reference ranges (95% predictive interval) for wall thickness were 1.6-3.6 mm for the stomach, 1.9-3.2 mm for the duodenum, 1.9-3.1 mm for the jejunum, 1.3-2.2 mm for the colon, and 0.8-2.7 mm for the cecum. Intraobserver wall thickness CV ranged from 8 to 21% for the 2 observers for 5 gastrointestinal segments. The interobserver bias for wall thickness measurements was not significant except for the stomach (0.14 mm, P < .05) and duodenum (0.29 mm, P < .05). Diagnostic images of mural blood flow could not be obtained. Asymptomatic intussusceptions were found in 10/18 neonates. Associations between sonographic variables or age and the presence of intussusceptions were not found.

Conclusions And Clinical Importance: Sonographic characteristics of the GI tract of normal Standardbred neonates can be useful in evaluating ill foals. Asymptomatic small intestinal intussusceptions occur in normal Standardbred neonates.