SCANNING AND ELECTRON MICROSCOPIC STUDY OF CANINEMEGAESOPHAGUS AND ITS MANAGEMENT

The present clinical study was carried on 18 clinical cases of megaesophagus reported to Campus Veterinary Hospital. The disease was encountered in Labrador (2 dogs), Golden Retriever (2 Dogs), German Shepherd (5 Dogs), Doberman (2 Dogs), Mongrel (3 Dogs), Pomeranian (2 Dogs), Cocker Spaniel (1 Dog) and Boxer (1 Dog) breeds of dogs. The mean age of occurrence was found to be 6.25 ± 0.88 years. Out of these 18 dogs, 11 were found to be males (61.12 %) and the rest were females (7 dogs; 38.88%). All these 18 dogs showed the signs of regurgitation of the food soon after food consumption. The haematological and biochemical studies showed that all the parameters studied were with in the normal range, except for haemoglobin. Ultrasonography did not reveal any sort of esophageal pathology. Radiographic features of megaesophagus in the seven dogs were air filled dilated esophagus and tracheoesophageal stripe sign. Esophagography clearly revealed generalized distention of esophagus in all the 18 dogs while endoscopy revealed markedly dilated, flaccid esophagus. Among the three treatment regimens tested, Metoclopramide combined with feeding the dogs in an upright position from an elevated platform improved the esophageal function to the maximum extent. Post mortem examination of the seven dogs died or euthanized showed severe dilatation and thinning of the esophageal wall, while histopathological examination showed scanty muscle bundles, Infiltration of polymorphonuclear. Scanning electron microscopy revealed destruction of blood vessels, loss of normal architecture and direction of inner circular as well as outer longitudinal muscle fibers while, transmission electron microscopic examination showed complete loss of cellular architecture, complete loss of architecture of myoneuronal plate at the neuromuscular junction suggestive of megaesophagus is a neuromuscular disorder.