Esophageal pH-monitoring in nonbrachycephalic dogs; a reference.

OBJECTIVE: To establish parameters that describe acidic gastroesophageal reflux (GER) events in nonbrachycephalic, hospitalized dogs without gastrointestinal disease following short total intravenous anesthesia, to establish upper reference limits for parameters that describe GER. STUDY DESIGN: Clinical prospective study. ANIMALS: Healthy, client-owned dogs presenting for elective orthopedic surgery. METHODS: Dogs were sedated with IM methadone (0.2 mg/kg) and medetomidine (5 ug/kg), followed by alfaxalone total intravenous anesthesia. The Digitrapper esophageal dual pH monitoring probe was placed transnasally into the esophagus. Dogs were unsedated during the subsequent recording period. A GER event was defined as esophageal pH less than 4.0. Parameters that described GER were: (1) number of GER events per hour, and (2) cumulative esophageal acid exposure (percentage of recording duration) at each sensor. Upper reference limits were calculated for each parameter. RESULTS: Thirty-five dogs were included (median age 7 years, range 1-12). The median recording duration was 21.1 h (range 13.6-29.3). Productive regurgitation was not noted in any dog. The median number of distal and proximal GER events per hour was 0.3 (range 0-4.3) and 0 (range 0-1), respectively. The median cumulative distal and proximal esophageal acid exposure was 0.2% (range 0.3-9%) and 0% (range 0%-1%), respectively. CONCLUSION: Upper reference limits for distal and proximal GER per hour was 2.4 and 0.4, respectively, and, for cumulative distal and proximal esophageal acid exposure, 2.3% and 0%, respectively. CLINICAL SIGNIFICANCE: Dogs undergoing esophageal pH monitoring in a similar hospital setting with parameters above these upper reference limits have excessive GER.

Quantification of gastroesophageal regurgitation in brachycephalic dogs.

BACKGROUND: Gastroesophageal reflux and regurgitation occurs in brachycephalic dogs, but objective assessment is lacking. OBJECTIVES: Quantify reflux in brachycephalic dogs using an esophageal pH probe and determine the association with scored clinical observations. ANIMALS: Fifty-one brachycephalic dogs. METHODS: Case review study. Signs of respiratory and gastrointestinal disease severity were graded based on owner assessment. An esophageal pH probe with 2 pH sensors was placed for 18-24 hours in brachycephalic dogs that presented for upper airway assessment. Proximal and distal reflux were indicated by detection of fluid with a pH ≤4. The median reflux per hour, percentage time pH ≤4, number of refluxes ≥5 minutes and longest reflux event for distal and proximal sensors were recorded. Association of preoperative respiratory and gastrointestinal grade, laryngeal collapse grade, and previous airway surgery with the distal percentage time pH ≤4 was examined using 1-way ANOVA. RESULTS: A total of 43 of 51 dogs (84%; 95% confidence interval 72-92) displayed abnormal reflux with a median (range) distal percentage time pH ≤4 of 6.4 (2.5-36.1). There was no significant association between the distal percentage time pH ≤4 and respiratory grade, gastrointestinal grade, laryngeal collapse grade, or previous upper airway surgery. CONCLUSIONS AND CLINICAL IMPORTANCE: The occurrence of reflux is not associated with owner-assessed preoperative respiratory and gastrointestinal grade, laryngeal collapse grade, and previous airway surgery. Esophageal pH measurement provides an objective assessment tool before and after surgery.

Circumferential esophageal hiatal rim reconstruction for treatment of persistent regurgitation in brachycephalic dogs: 29 cases (2016-2019).

OBJECTIVE: To describe a technique for circumferential esophageal hiatal rim reconstruction and to report outcomes in brachycephalic dogs with persistent regurgitation treated with the technique. ANIMALS: 29 client-owned brachycephalic dogs. PROCEDURES: Dogs that had undergone circumferential esophageal hiatal rim reconstruction between January 1, 2016, and December 31, 2019, for treatment of persistent regurgitation were identified through a search of the medical record database of The Animal Hospital at Murdoch University. Circumferential esophageal hiatal rim reconstruction involved apposition of the medial margins of the left and right pars lumbalis dorsal to the esophagus (reconstructing the dorsal margin) and ventral to the esophagus (reducing the ventral hiatal aperture and completing the circumferential reconstruction). Data collection from the medical records included preoperative, intraoperative, and postoperative (short- and long-term outcomes [≤ 14 days and ≥ 6 months, respectively]) data. RESULTS: In all dogs, substantial laxity of the left and right pars lumbalis and failure of dorsal coaxial alignment were observed, and circumferential esophageal hiatal rim reconstruction and esophagopexy were performed. Results of short-term follow-up indicated reduced regurgitation frequency; however, 7 of 29 dogs continued to have mild regurgitation, which was attributed to esophagitis and resolved with medical management. Long-term follow-up information was available for 19 dogs: regurgitation had resolved in 16 dogs and occurred once weekly in 3 dogs. No ongoing medication was required for any dog. CONCLUSIONS AND CLINICAL RELEVANCE: Circumferential hiatal rim reconstruction combined with esophagopexy substantially reduced regurgitation frequency in dogs of the present study, and we recommend that this procedure be considered for brachycephalic dogs presented with a history of regurgitation unresponsive to medical management.

Kinetic Gait Analysis of Agility Dogs Entering the A-Frame.

OBJECTIVE: The main purpose of this study was to investigate the effect of a decrease in the A-frame angle of incline on the vertical and cranio-caudal ground reaction forces observed in a homogeneous cohort of agility dogs during entrance and contact with the A-frame. MATERIALS AND METHODS: A crossover study design was applied to eight large breed dogs to compare the vertical and cranio-caudal ground reaction forces entering the A-frame at three angles of incline: 40° (standard), 35° and 30°. The peak vertical force, passive impact peak, peak propulsive force, peak braking force, the time point (percentile) in the stance phase at which these events occurred and the proportion of time for limb contact spent in braking (% braking) and propulsion (% propulsion) were examined.The variables measured from three trials at each incline were evaluated for a significant effect of A-frame angle with height and velocity included as covariates. RESULTS: The peak propulsive force and the % propulsion were significantly higher at the 40° angle of incline compared with 30° (p = 0.013, p = 0.0165 respectively) and the % braking was significantly lower at the 40° angle of incline compared with 30° (p = 0.0165). There was no significant effect of A-frame angle on the vertical ground reaction forces measured. CLINICAL SIGNIFICANCE: Compared with 30° incline, ascent up the A-frame at a 40° incline requires a higher propulsive force and extended time in propulsion to maintain forward movement and convert potential energy into forward kinetic energy.

Reduction of the A-Frame Angle of Incline does not Change the Maximum Carpal Joint Extension Angle in Agility Dogs Entering the A-Frame.

OBJECTIVE: This article aims to investigate the effect of a decrease in the A-frame angle of incline on the highest carpal extension angle in agility dogs. METHODS: Kinematic gait analysis (two-dimensional) measuring carpal extension was performed on 40 dogs entering the A-frame at 3 angles of incline: 40° (standard), 35° and 30°. The highest carpal extension angle from three trials at each incline was examined for a significant effect of A-frame angle with height, body weight and velocity included as covariates. RESULTS: There was no significant effect of A-frame angle on the highest carpal joint extension angle for the first or second limb. The adjusted mean carpal extension angle for the first limb at 40° was 64° [95% confidence interval (CI), 60-68), at 35° was 61° (95% CI, 57-65) and at 30° was 62° (95% CI, 59-65). The raw mean carpal extension angle for all dogs across all A-frame angles for the first limb was 62° (95% CI, 60-64) and the second limb was 61° (95% CI, 59-63). CLINICAL SIGNIFICANCE: Decreasing the A-frame angle of incline from 40° to 30° did not result in reduced carpal extension angles. The failure to find a difference and the narrow CI of the carpal angles may indicate that the physiologic limits of carpal extension were reached at all A-frame angles.