Ambulatory esophageal pHmetry in healthy dogs with and without the influence of general anesthesia

Abstract

This research aimed to determine the value of esophageal pH in awake and anesthetized dogs, to evaluate the esophageal pH value in awake dogs, in different body positions, as well as to study the occurrence of gastroesophageal reflux episodes in these positions. Thus, 40 healthy male and female adult dogs with mean body weight of 15.5 ± 4.6 kg were used. Esophageal pHmetry was conducted by inserting a catheter through the oropharynx in 30 dogs (stage 1) anesthetized with acepromazine, propofol and isoflurane, submitted to elective ovariosalpingohysterectomy. In addition, 8-h esophageal pHmetry was carried out transnasally in 10 awake dogs (stage 2), allowed to move and change body positions (lateral and sternal decubitus, and standing position), which were recorded. The mean esophageal pH value was lower (p < 0.01) in the anesthetized dogs (7.3 ± 0.82) than in the awake dogs (8.2 ± 0.3). Only four anesthetized dogs (13.33%) suffered reflux episodes. Reflux was not observed in the awake dogs and no esophageal pH differences were found between the body positions studied. Compared to the alert state, general anesthesia in dogs submitted to the previously mentioned anesthesia protocol causes esophageal pH reduction and predisposes to the occurrence of gastroesophageal reflux episodes. Transnasal pHmetry of 8 h in healthy awake dogs reveals that the esophageal pH value is alkaline and does not vary according to body position. In these animals, decubitus position is not a determining factor for reflux episodes to occur.

Wireless Ambulatory Esophageal pH Monitoring in Dogs with Clinical Signs Interpreted as Gastroesophageal Reflux

“…When the results from both groups were compared, no statistically significant differences could be found. Our normal ambulatory esophageal pH values correlated well with those published so far in dogs . To the authors' knowledge, ambulatory esophageal pH monitoring in awake dogs has only been performed with a catheter‐based system.…”

“…Similarly, in a study establishing a canine GERD model, the distal esophageal pH environment of 21 awake female mongrel dogs with cervical esophagopexy and in‐dwelling pH catheters was documented over the course of 24 hours, and the fractional time pH < 4 also was low, with a median of 0.1%, and a mean of 0.43% (range, 0–3.59%) . Our noninvasively recorded pH data are similar to McMahon's catheter‐based results, although we demonstrated a higher total number of reflux episodes ([10; range, 1–65] versus [2; range, 0–46]) and overall longer single reflux episodes ([8 minutes; range, 0–27] versus [1 minutes; range, 0–16]) . Concurrent investigation of both gastric and esophageal pH values in healthy dogs was performed because conflicting data exist on canine gastric pH, suggesting higher pH values compared to humans, and results of a recent study using the Bravo system for monitoring canine gastric pH were not available at the time of investigation.…”

“…In that study, esophageal pH values were recorded every minute for 8 hours. Not a single reflux episode was observed in any of the 10 awake female dogs during the observation period, and the esophageal pH remained continuously in a weakly alkaline range . Similarly, in a study establishing a canine GERD model, the distal esophageal pH environment of 21 awake female mongrel dogs with cervical esophagopexy and in‐dwelling pH catheters was documented over the course of 24 hours, and the fractional time pH < 4 also was low, with a median of 0.1%, and a mean of 0.43% (range, 0–3.59%) .…”

Idiopathic esophagopathies resembling gastroesophageal reflux disease in dogs

“…The presence of physiologic and pathologic GER has been demonstrated in humans and dogs by specific diagnostic procedures such as esophageal pH measurements (10,13). In contrast to humans, because of practical limitations, such diagnostic procedures remain of experimental nature in dogs (17,37). Therefore, the recognition of pathologic GER in clinical practice still remains a diagnosis of exclusion.…”

“…In dogs, the association between GER and esophageal complications is clinically still not proven, because specific diagnostic tools such as esophageal pH monitoring, esophageal manometry, and esophageal impedance measurement are typically not used in clinical settings (17,42). In naturally diseased dogs esophageal complications presumed to be caused by pathologic GER are most commonly reported secondary to previous anaesthesia and surgical interventions (1,25,27,33,39,57), or secondary to structural anomalies such as hiatal hernias, megaesophagus, and neoplasia (8,11,20,32,34).…”