Processed aortic allografts for oesophagoplasty in dogs

Abstract

The study was conducted with the objectives of a. Preparation, preservation and evaluation of chrome/ glutaraldehyde cross linked aortic tissue of dogs and to compare the relative acceptability and efficacy of them for cervical oesophagoplasty in dogs, and b. Evaluation of modified pharyngostomy feeding method and its effect on healing at cervical oesophagoplasty site in dogs. The experiment was conducted in thirty, apparently healthy, adult, nondescript dogs of either sex weighing 9-13 kg. The animals were randomly divided into three groups viz.,, group I, II and III. Group II and III were subdivided into two subgroups each, namely IIA, IIB and iilA, IIIB. Group I and the subgroups consisted of six animals each. Animals of group I were subjected to sham operation. Cervical oesophagoplasty using chrome processed aortic allograft and glutaraldehyde processed aortic allograft were performed in animals of group II and III respectively. Pharyngostomy tube feeding was instituted in three animals of group I and all animals of subgroups IIB and IIIB. Tissue samples of thoracic aorta harvested from dogs, processed and crosslinked with chromic sulfate and glutaraldehyde were used as graft materials. Chrome processed aorta showed better biomechanical qualities except for tensile strength than glutaraldehyde processed aorta. The grafts had fairly good handling qualities and shelf life. All the animals were premedicated with triflupromazine hydrochloride and anaesthetized using thiopentone sodium to effect. Wound, oval in shape measuring 3-4 cm long and l/3rd of the circumference of the oesophagus was created in all experimental animals. Oesophagoplasty was performed by fixing the graft material over the defect using 5-0 braided silk thread and continuous lock stitch sutures. Left side' pharyngostomy was performed in 15 dogs. Suitably designed siliconised catheter made up of modified polyvinyl chloride with an attached X-ray opaque line was used as pharyngostomy tube. The tube was kept in situ for a period of 15 days postoperatively for administration of fluid diet. The animals were kept under observation for varying periods of 15, 30 and 60 days postoperatively. The animals of subgroups IIB and IIIB became alert and active earlier than that of IIA and IIIA. At the cervical region, the operated site showed mild inflammatory reaction by 1-2 days postoperatively in all animals. The sutures were removed after normal healing by 7-8th day in all animals except one each in subgroup IIA and IIIB, where it was removed on the 10th day. Mild bleeding while performing pharyngostomy (one dog) and moderate pain and slight swelling around the pharyngostomy tube entrance site (3 dogs) were observed in subgroup IIB. One animal in subgroup IIIB showed severe inflammatory oedema around the tube entrance site. Tolerance of pharyngostomy tube was excellent in 13 dogs. The pharyngostomy wound healed completely by 14-15th day after removal of the tube in all the dogs. All the animals started feeding on liquid food by seventh day postoperatively in subgroups IIA and IIIA following hyperalimentation via intravenous route and by 15th day in subgroups IIB and IIIB following hyperalimentation via pharyngostomy tube. They maintained normal apetite and feeding habits thereafter during the period of observation. Mild swelling at the operated site while swallowing (3 dogs) and vomiting (one dog) were noticed among the animals of subgroup IIA and IIIA. Initial tube obstruction during first feeding (6 dogs), vomiting after first feeding (2 dogs) and mild diarrhoea (one dog) were observed among animals of subgroup IIB and IIIB.