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What is Feline esophagus is: and explain in detail?
Ref. API Textbook of Medicine. Pg. 1690
 
Feline Esophagus

Feline esophagus also known as oesophageal shiver ,refers to the transient transverse bands seen in the mid  and lower esophagus on a double contrast barium swallow .
The appearance is almost always associated with active gastro-esophageal reflux and is thought to be due to contraction of muscularis muosa with resultant shortening of the esophagus and "bunching up" of mucosa in the lumen .