Mechanical dilation, botulinum toxin A injection, and surgical myotomy with fundoplication for treatment of lower esophageal sphincter achalasia-like syndrome in dogs

Background Megaesophagus (ME) carries a poor long-term prognosis in dogs. In people, lower esophageal sphincter (LES) achalasia is a rare cause of ME that may respond to targeted intervention. Dogs with lower esophageal sphincter achalasia-like syndrome (LES-AS) have been described recently, warranting investigation of analogous targeted treatment. Hypothesis/Objectives Evaluate response of dogs with LES-AS to LES mechanical dilation and botulinum toxin A (BTA) injections, with or without surgical myotomy and fundoplication. We hypothesized that clinical and videofluoroscopic swallow study (VFSS) features of LES-AS would improve after treatment targeting functional LES obstruction. Animals Fourteen client-owned dogs with LES-AS diagnosed by VFSS. Methods Retrospective study. Dogs diagnosed with LES-AS underwent treatment between April 2015 and December 2017. Outcome measures included client perception of clinical severity, body weight (BW), body condition score (BCS), regurgitation frequency, and VFSS parameters (ME, esophageal motility, gastric filling). Dogs with positive responses were considered candidates for LES myotomy with fundoplication. Results By a median IQR of 21 (IQR, 14-25) days after mechanical dilation and BTA, clients reported clinical improvement in 100% of dogs, BW increased 20.4% (IQR, 12.7%-25%), pre- and post-treatment BCS was 3 (IQR, 3-4) and 5 (IQR, 4-5), respectively, and frequency of regurgitation decreased by 80% (IQR, 50%-85%). Duration of effect was 40 (IQR, 17-53) days. Despite clinical improvement, ME and abnormal esophageal motility persisted in 14 dogs. Six dogs subsequently underwent myotomy and fundoplication and maintained improvement observed after mechanical dilation and BTA. Conclusions and Clinical Importance Dogs with LES-AS experienced significant, temporary, clinical improvement after mechanical dilation and BTA. Preliminary results suggest myotomy with fundoplication provide lasting clinical benefit despite persistence of ME.