Evaluation of the efficacy of diaphragmatic and omental transplants at the gastroesophageal junction in dogs

Abstract

The study was undertaken with the objectives of designing a surgical approach to the gastroesophageal region in dogs and to evaluate the efficacy of diaphragmatic and omental grafting at the gastroesophageal myotomy site. The study was conducted in 30 adult dogs of either sex divided into five groups of six animals each. The animals were premedicated with atropine sulphace (0.04 mg/kg body weight) and xylazine (0.5 mg/kg body weight) IM. Anaesthesia was induced and maintained with five per cent solution of thiopentone sodium to effect. Induction of anaesthesia and recovery was smooth and uneventful and the duration was satisfactory. Respiratory arrest observed in a few animals could be corrected except in one and respiration was maintained with respiration pump or Boyles' Tec anaesthetic apparatus. Gastroesophageal myotomy was performed through left side thoracotomy with resection of eighth rib in animals of Group I and by laparotomy, through the 12th intercostal space with resection of 12th rib in animals of Group 11, to study the suitability of surgical approaches.

Abdominal approach adopted in Group II was found suitable for experimental approach and was adopted in animals of Groups III, IV and V. In the animals of Groups III, IV and V gastroesophageal myotomy was performed and the myotomy edges were sutured to the overlying portion of diaphragm in Group III, to a deflected portion of diaphragmatic pedicle graft in Group IV and to a deflected portion of omental pedicle graft in Group V. The animals were kept under observation for 21 days post operatively and observed for physiological changes, clinical signs, haematologic, radiographic and electrocardiogram changes. Physiological parameters showed a significant decrease in rectal temperature upto 90th min after surgery and significant increase in pulse and respiration rate upto 24 h. All the animals were alert and active throughout the period of observation. Feed intake and swallowing was normal. Skin wound had healed without complications in all the animals. Haemogram showed normal haemoglobin concentration, erythrocyte sedimentation rate and packed cell volume throughout the period of observation in all the animals. Erythrocyte count was within normal range in all the animals except for a transient decrease in Group I and leucocyte count showed an increase in Group V. An increase in neutrophil count was observed on the 7th and 14th day in Groups III and V with a corresponding decrease in lymphocyte count. Monocyte

count was normal in all the animals and oesinophil count showed a decrease in Group I. The values returned to normal range by 21st day in all the animals. The electrocardiogram changes observed during surgery and in post operative period were spontaneously corrected. Contrast radiography of the oesophagus and stomach revealed normal emptying and absence of leakage. Narrowing' of the caudal end of thoracic oesophagus along with dilatation of the stomach was observed in one animal and dilatation of stomach alone was observed in two animals. Contrast radiography of the autopsy specimen of oesophagus and stomach of one animal each from Group I and 11 revealed increased width of gastroesophageal region and an outpouching of the stomach at the greater curvature. Gross morphological examination on autopsy in Group I revealed adhesion of lung with thoracic wall, diaphragm and oesophagus, congestion and consolidation of lung, collapse of the lung lobes and mediastinial pleuritis in a few animals. Fibrous tissue covering over the caudal end of thoracic oesophagus was also seen in two animals. Adhesion of omentum with abdominal wall and diaphragm was the autopsy changes noticed in Group 11.

Oesophagus was normal in size in all the animals except in one animal where slight narrowing at the caudal end was observed. Increased width at the gastroesophageal region was evident in all the animals. An outpouching at the greater curvature of the stomach was seen in all animals except three where slight dilation and flaccidity of the stomach was noticed. The myotomy site was thin in Groups I, II and V. In Groups III, the portion of diaphragm sutured to the myotomy wound was firmly adherent with it and in Group IV, the diaphragm pedicle graft sutured to the myotomy wound has healed and was firmly adherent to the myotomy site. In Group V, the omental pedicle graft sutured to the myotomy site has healed completely and was indistinguishable. On histological examination no sign of inflammation was noticed in the mucosa and submucosa. . At the myotomy site fibrovascular connective tissue proliferation was observed in all the groups. In Groups III and IV peripheral to the fibrovascular connective tissue,the fascicles of diaphragmatic muscle fibrils were observed. In Group V beneath the thin fibrovascular layer infiltration of plasma cells, lymphocytes, macrophages and a few neutrophils were observed extending into the stroma and lamina propria. A layer of fibrous connective tissue was observed as the outermost layer over the thin fibrovascular layer and contained a few fat cells in one animal.