Propulcid/Cisapride. vs Reglan/Metachlopramide:
These are promotility drugs and are said to affect the two sphincters at opposite ends of the stomach differently. Nexium and Prilosec are similar to one another as acid inhibitors.

Found these articles about the effect of bethanechol in the esophagus of human patients (applying research in humans to animal care, isn’t that a switch?). Peristalsis is the muscle contraction that squeezes food down the GI tract. The enteric nervous system is unidirectional, so normal peristalsis occurs in one direction (towards the rectum). The first study looked at its use in humans with ineffective esophageal motility. It found that bethanechol increased contractions in the lower esophagus for 20 minutes for viscous and liquid swallows and for forty minutes for liquid. The second study looked at the qualities of peristalsis in infants with reflux before administration of bethanechol and after. Bethanechol improved lower esophageal motility more than the middle esophagus and had no effect on the upper third of the esophagus. It also increased the lower esophageal sphincter tone. Additionally, one theory of reflux is that once there is acid in the lower esophagus, a reflex causes the lower esophageal sphincter (LES) (between the esophagus and the stomach) to relax, worsening the reflux. A tight LES would be a problem by itself in our pups, but by increasing the peristalsis of the lower esophagus, it is most likely doing more good than harm (yay, Niko!)
Interesting study for MG; pyridostigmine (Mestinon) also increases esophageal motility, and in this study, better than bethanechol.
J Clin Gastroenterol. 2009 Mar;43(3):253-60.

The effect of oral buspirone, pyridostigmine, and bethanechol on esophageal function evaluated with combined multichannel esophageal impedance-manometry in healthy volunteers:
Blonski W, Vela MF, Freeman J, Sharma N, Castell DO.
Source
Division of Gastroenterology, Medical University of South Carolina, Charleston, SC 29425, USA. blonskiw@musc.edu
Abstract

BACKGROUND:
There is limited information on medications with promotility effects on the esophagus. Studies in healthy volunteers have shown the potential role of the direct cholinergic agonist bethanechol and the serotonin receptor agonist buspirone in improving esophageal motility. It has been also shown that an acetylcholinesterase inhibitor, the short-acting drug edrophonium administered intravenously caused a greater increase in the esophageal contraction amplitude and duration than bethanechol. Edrophonium cannot be used as a promotility therapy owing to short duration of action and lack of oral administration. The use of another acetylcholinesterase inhibitor pyridostygmine with longer duration of action has not been studied. The aim of the study was to evaluate the effect of oral pyridostygmine (60 mg), buspirone (20 mg), and bethanechol (25 mg) on esophageal function assessed by combined multichannel intraluminal impedance-esophageal manometry.

MATERIALS AND METHODS:
Ten healthy volunteers were enrolled in a double blind randomized 3-period crossover study. Multichannel intraluminal impedance-esophageal manometry recorded esophageal pressures and bolus transit data during 6 liquid and 6 viscous swallows at baseline and 20, 40, and 60 minutes after the randomized oral administration of each drug.

RESULTS:
Blinded analysis found significant increases in mean distal esophageal amplitude for liquid swallows from baseline to 60 minutes postdosing after pyridostygmine (87.6 vs. 118.0 mm Hg, P<0.001), buspirone (85.1 vs. 101.9 mm Hg, P<0.05), and bethanechol (87.6 vs. 118.8 mm Hg, P<0.01). Only pyridostygmine showed a significant decrease in mean distal onset velocity for liquid swallows at 60 minutes postdosing (3.4 vs. 2.3 cm/s, P<0.01) and increase in total bolus transit time at 60 minutes postdosing (7.9 vs. 9.3 s, P<0.05). All 3 agents significantly increased mean lower esophageal sphincter residual pressure for liquid swallows at 20, 40, and 60 minutes postdosing. Increased lower esophageal sphincter resting pressure was not significant. Similar results were found with viscous swallows.

CONCLUSIONS:
Oral pyridostygmine, buspirone, and bethanechol enhance esophageal motility with pyridostygmine appearing to have the greatest effect. A potential effect on improving esophageal function and symptoms in patients requires further study.

Here is link to the study that my vet based part of is decision to try Bethanechol with Niko….http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1696374/pdf/canvetj00412-0014.pdf