Detection of silent reflux events by nuclear scintigraphy in healthy dogs

BACKGROUND: Reflux and aspiration in people are associated with respiratory disease, whereas approximately 50% of healthy adults microaspirate without apparent consequence. In dogs, analogous information is lacking. HYPOTHESIS: Healthy dogs commonly have gastroesophageal reflux and a proportion of these dogs will have laryngopharyngeal reflux with silent aspiration. ANIMALS: Twelve healthy, client‐owned dogs. METHODS: Prospective study: Dogs were free‐fed a meal containing (111 MBq) colloidal (99)m‐technetium phytate. Dynamic‐scans were performed 5 and 30 minutes postingestion. Time‐activity curves, reflux margination, volume, frequency, and duration were evaluated over 7 regions of interest in dorsal ± left‐lateral recumbency. Static scans (dorsal recumbency) were performed 2 and 18 hours postfeeding to detect aspiration. Reflux and aspiration were defined as counts ≥200% background activity ± decreased gastric counts. Between‐group comparisons were performed by Wilcoxon rank‐sum test or one‐way ANOVA on ranks with significance of P < .05. RESULTS: In this study, reflux of variable magnitude was detected in 12/12 dogs. No significant differences in outcome parameters were detected with recumbency (P > .05). Margination to the pharynx and proximal, middle, and distal esophagus was identified in 5/12, 2/12, 3/12, and 2/12 dogs, respectively. Median (IQR) reflux frequency and duration were 2 events/5 minutes (1‐3.3 events/5 minutes) and 6 seconds (4‐9 seconds) respectively. No dog had detectable aspiration. CONCLUSIONS AND CLINICAL IMPORTANCE: Nuclear scintigraphy can document reflux in dogs. Reflux, but not aspiration, is common in healthy dogs and must be considered when interpreting results in clinically affected dogs.