PhD

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 IIIA, 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 1/3rd 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 IS, 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.

A marginal increase in rectal temperature and pulse rate,
a gradual decrease in respiration rate, slight palor of
conjunctival mucosa, marginal prolongation of capillary refil
time, and time taken for skin to return to normal position
were observed during early postoperative period in all
experimental animals.
A marginal decrease in haemoglobin concentration and
packed cell volume, a marginal increase in erythrocyte
sedimentation rate, total erythrocyte and leucocyte count were
the salient features of haemogram during early postoperative
period in all subgroups.
Differential count showed mild neutrophilia in all
subgroups except IIIB. An increase in lymphocyte count in
subgroup IIIA and IIIB with marginal variations in other
subgroups was observed. Monocyte and eosinophil count showed
marginal variation during the period of observation in all
subgroups.
During early period of observation, a decrease in total
serum protein and albumin content was noticed in all
subgroups. Serum globulin content showed an increase in
subgroups IIB and IIIA and a decrease in subgroup IIA and
IIIB. Albumin-globulin ratio showed an increase in subgroups
IIA and IIIB and a decrease in subgroups IIB and IIIA. All
animals regained near normalcy by 15th day postoperatively.

Marginal variation in serum sodium,



potassium and



chloride concentration during the period of observation was
noticed in all subgroups.
Oesophagogram during postoperative period showed normal
oesophageal emptying and did not reveal signs of any
complication.
Gross pathological changes were not observed on cervical
oesophagus externally in 18 experimental animals. Weak
fibrinous adhesions between grafted site and perioesophageal
cervical muscles were noticed in one dog each in subgroup IIA
and IIIB and two dogs each in subgroups IIB and IIIA.
Gross pathological changes were not observed on entire
oesophageal mucosa in 23 experimental animals. Mild hyperaemia
of the oesophageal mucosa at its posterior third was observed
in one dog of subgroup IIB.
,
Healing site of oesophagoplasty showed a steady increase
in tensile strength, breaking strength, extensibility arid
energy absorption during the period of observation.
Total dilatation capacity at the grafted site was showing
a reduction on 30th day postoperatively followed by an
increase on 60th day. Grafted site with glutaraldehyde
processed graft was showing comparatively higher values for


all parameters than that of chrome processed graft on 60th day
postoperatively.
Healing at the grafted site was complete by 15th day.
Regeneration of mucosa from sides of the graft material was
grossly visible, which covered the whole graft by 30th day and
became thicker and normal oesophageal folds were seen on 60th
day. Mild corded thickening of the mucosa boardering the
grafted material was observed in one animal of subgroup IIA,
and two animals each of subgroups IIIA and IIIB.
Histomorphological studies by 15th day postoperatively
revealed mild inflammatory reaction characterised by the
presence of pOlymorphonuclear cells, lymphocytes and a few
macrophages at the site. Scattered fibroplasia, neovasculari-
sation and disintegration of elastic fibres were salient
features in lamina propria.
On 30th day, proliferation of lining mucosa, moderate
fibroplasia and absence of oesophageal glands in lamina
propria were evident.
By 60th day, the squamous cell epithelial lining was
slightly hyperplastic, the lamina propria was devoid of
oesophageal glands and muscular layer showed proper
orientation of collagen and elastic fibres.