Summary
This report describes the treatment of a 17‐year‐old American Quarter Horse gelding for an oesophageal obstruction of approximately 24 h’ duration. An intraluminal oesophageal mass resembling a phytobezoar and located close to the cardia, was observed during endoscopic examination of the oesophagus of a horse showing signs of oesophageal obstruction. An intrathoracic oesophageal diverticulum, filled with fluid, was observed about 40 cm proximal to the obstruction. The end of a nasogastric tube was guided beyond the diverticulum, using gastroscopic observation, so that its tip rested close to the obstruction. The obstruction failed to disintegrate or move into the stomach despite vigorous, prolonged lavage. With the nasogastric tube left in place, and the horse's head elevated, 0.5 L cola was administered adjacent to the obstruction through the nasogastric tube. The head was maintained in the elevated position for an hour, after which time the head was lowered and oesophageal lavage resumed. The nasogastric tube was passed into the stomach within 3 min of re‐instituting lavage. The successful use of a carbonated beverage to treat human patients for oesophageal or gastrointestinal obstruction caused by a phytobezoar is well documented. Carbonated beverages have also been reported to be effective in treating horses for gastric and enteric impactions caused by persimmon seeds. Administering cola into the oesophagus may help resolve oesophageal obstruction of horses caused by a phytobezoar or impacted feed material when horses are refractory to other treatments.
OBJECTIVE
To compare the pharmacokinetics between repeated doses and to characterize changes in the fecal microbiome after oral and rectal multidose misoprostol administration.
ANIMALS
6 healthy university-owned geldings.
PROCEDURES
In a randomized, crossover study, misoprostol (5 μg/kg) was administered orally or rectally every 8 hours for 10 doses, or not administered (control), with a 21-day washout between treatments. Concentration-versus-time data for dose 1 and dose 10 were subject to noncompartmental analysis. For microbiota analysis using 16S rRNA amplicon sequencing, manure was collected 7 days before study onset, immediately before dose 1, and 6 hours, 7 days, and 14 days after dose 10, with time-matched points in controls.
RESULTS
Repeated dosing-related differences in pharmacokinetic parameters were not detected for either administration route. The area under the concentration-versus-time curve was greater (P < .04) after oral versus rectal administration. The relative bioavailability of rectal administration was 4 to 86% of that of oral administration. Microbial composition, richness, and β-diversity differed among subjects (P < .001 all) while only composition differed between treatments (P ≤ .01). Richness was decreased 6 hours after dose 10 and at the control-matched time point (P = .0109) in all subjects. No other differences for time points, treatments, or their interactions were observed.
CLINICAL RELEVANCE
Differences in systemic exposure were associated with the route of administration but were not detected after repeated administration of misoprostol. Differences in microbiota parameters were primarily associated with interindividual variation and management rather than misoprostol administration.
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