Tracheal reconstruction in dogs under acepromazine - thiopental anaesthesia

Abstract

The experiment was conducted on twelve, apparently healthy, adult, nondescript dogs of either sex, divided into two groups, viz., Group 1 and Group 11, each consisting of six animals. Circumferential resection of two adjacent tracheal rings of the cervical trachea was performed and the trachea was reconstructed by end – to – end anastomosis in the animals of Group 1 and with Marlex mesh prosthesis in the animals of Group 11. All the animals were premedicated with acepromazine maleate IM, and anaesthesia was induced by 2.5 per cent solution of thiopentone sodium IV. Induction of anaesthesia was complete by 3.26 + 0.10 minutes, duration of surgical anaesthesia was 65.00 + 3.29 minutes and time for recovery was 192.91 + 13.68 minutes. Variation in the physiological and haematological parameters during anaesthesia were not significant. In Group 1, all the animals had normal respiratory function throughout the period of observation, following surgery. In Group 11, all the animals, except one, developed severe complications and died within one to four weeks postoperatively. Only one dog survived in this group and was sacrificed on the 45th postoperative day. During the postoperative period, the rectal temperature did not show marked variations in both the groups. The pulse and respiration rates showed an initial increase in Group 1. However in Group 11, marked decrease in pulse rate and increase in respiration rate was noticed. Hemogram on the different postoperative days showed an increase in the total leucocyte count in both the groups, and increase in monocyte and eosinophil count in Group 11. Radiography on different postoperative days in Group 1 demonstrated that there was no reduction in the size of the tracheal lumen at the site of anastomosis in five of the six animals. In Group 11, radiography revealed a progressive reduction in the size of the tracheal lumen at the site of reconstruction in four animals, and only slight reduction in one dog on the 45th postoperative day. At autopsy, gross examination of the trachea at the site of anastomosis in Group 1 showed mild to moderate adhesions to the adjacent tissue and there was no reduction in the size of the tracheal lumen in five of the six dogs of this group. In animals of Group 11, dense adhesion between the site of reconstruction and adjacent tissue was observed. The mesh was fully incorporated at the site of reconstruction in five of the six animals. One animal had shown anastomotic dehiscence. Almost complete occlusion of the trachea by overgrowth of tissue was observed in four animals and slight reduction in the tracheal lumen in one animal. Histopathology at the site of anastomosis in Group 1 revealed complete healing of all the layers of the trachea by the 30th postoperative day. In Group 11, tracheal stenosis was associated with ingrowth of granulation tissue in four animals. The mesh was infiltrated by fibrous tissue in five of the six animals. Epithelium was seen lining the prosthesis on the 45th postoperative day.