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==Treatment==
==Treatment==
The term subtotal colectomy describes the removal of the majority
of the colon. There are two variations of the technique depending
on whether the ileocaecocolic valve is preserved or removed. This
structure prevents reflux of colonic contents into the small intestine;
therefore, some surgeons consider that removing the valve will predispose
to bacterial overgrowth in the small intestine, steatorrhoea
and deconjugation of bile salts. The rationale for excision of the
valve is that it minimises the recurrence of segmental megacolon
and associated constipation. For the surgeon, an added complication
is that differentiation between diseased and normal tissue
cannot be reliably made by gross
evaluation at surgery.
Removing the majority of the colon
will undoubtedly have certain metabolic
effects on the animal. The colon
normally acts to absorb water along
an osmotic gradient created by active
sodium absorption. Bicarbonate ions
are secreted in exchange for chloride
ions, and potassium is lost from extracellular
fluid; in addition, mucus and cells are shed into the colon.
Questions remain about water and electrolyte homeostasis, and
absorption of specific nutrients such as vitamin K following subtotal
colectomy. Enteric function following subtotal colectomy has been
evaluated in both normal and clinically affected cats and no significant
clinical or subclinical evidence of abnormal bowel function
was found (Gregory and others 1990). Histology of the small
intestinal wall following subtotal colectomy showed increases in
villus height, enterocyte height and density, with an increased
mucosal absorptive area. Serum cobalamin and faecal sodium
levels were higher in cats treated surgically, and faecal potassium
was low; however, the significance of these findings is unknown.
Tenesmus and loose faeces are often seen immediately postsurgery,
with faeces gradually progressing to soft but formed by
about three months; resection of the ileocaecocolic valve is, however,
associated with persistence of looser stools.
The issue of exactly how much of the colon to remove will remain
controversial until more information is published regarding longterm
outcome and function. However, the author’s preference in
the majority of cases is to resect the ileocaecocolic valve and perform
enterocolostomy. If the ileocaecocolic valve is to be preserved,
the colon is transected 3 cm from the caecum to ensure a
tension-free colocolostomy (the short mesocolon restricts mobility).
It is essential that there is no longitudinal tension on the anastomosis
site postoperatively, as this is likely to lead to dehiscence, with
potentially disastrous results.
If the valve is resected and an enterocolostomy performed, the
disparity in luminal widths can be dealt with by oblique incision of
the ileal portion combined with a short antimesenteric incision to
spatulate the intestine. A single layer of full-thickness appositional
sutures using polydioxanone in a simple interrupted pattern is the
author’s preference. An end-to-end or end-to-side anastomosis can
also be created using surgical stapling equipment.
It should be noted that older surgical procedures such as coloplasty
and partial colectomy provide little or no long-term improvement
and are not recommended.
Complications associated with subtotal colectomy
Operative complications are uncommon. Where reported, complications generally relate to the anastomotic procedure; for example,
technical errors leading to dehiscence, or localised peritonitis resulting from contamination at surgery. The most commonly reported
complication in the long term is recurrence of constipation. The majority of these individuals can be managed medically, but some cases
will require repeat surgery.
==Prognosis==
==Prognosis==
==Links==
==Links==