Retrograde oesophageal contractions in the dog

Retrograde oesophageal contractions were observed by simultaneous radiography and electromyography during naturally occurring post-prandial eructations in six dogs. The contractions progressed cranially at 85 +/- 16 cm s-1 (S.E.M., n = 50) displacing, to the mouth, gastric gas which had previously passed into and distended the thoracic part of the oesophagus for 304 +/- 22 ms (S.E.M., n = 30). Ninety per cent (n = 100) of retrograde oesophageal contractions were followed immediately by a slower aboral contraction (17.1 +/- 0.02 cm s-1; S.E.M., n = 15). This appears to be the first description of naturally occurring retrograde oesophageal contractions in a non-ruminant animal.