Constipation is a frequent complaint middle aged to older cats. In some cases the disease becomes refractory enough to treatment
that either subtotal colectomy or euthanasia have to be considered. The problem is thought to be caused by underlying metabolic
problems in some patients such as kidney disease or other issues that generally result in dehydration. These are however relatively
rare and do not generally cause clinical signs. Most clinical cases of recurrent constipation/obstipation are idiopathic in
nature. Pelvic abnormalities and strictures represent some of the occasional causes of this problem that can be identified
with work up as is nerve trauma to the sacral region. Megacolon represents the extreme manifestation of obstipation/constipation.
In cats with megacolon abnormal smooth muscle cell function of the colon has been detected though this was in cats with advanced
disease so it is uncertain if this was truly the cause or a manifestation of chronic constipation.
The consequences of constipation/obstipation usually are metabolic derangements. With prolonged problems endotoxemia and even
death can occur. Long term this can also lead to megacolon, though in many cases megacolon can occur without a clear history
A variety of treatments have been recommended for the constipated/obstipated cat as well as the cat with megacolon.
When initially presented relieving the constipation is indicated. This can be done with a variety of ways, whereby manual
disimpaction is the least "nice" of the options and should be reserved for refractory cases. Enemas can often be helpful to
help to moisten dried out feces. In general 5 to 10 ml/kg of warm water can be given as an enema. Alternatively smaller volumes
of DSS (5 to 10 ml total dose) can be given, though this is more irritating. This can be supplemented with oral lactulose
and fluid therapy to maximize efficacy.
Recently we have adapted the use of PEG solutions administered via NE tube to help relieve obstipated/constipated cats. This
is similar to methods used in humans. We give PEG solution as a slow trickle via NE tube (4 to 18 hours). This generally results
in defecation within 6 to 12 hours. Obviously before embarking on this therapy it is wise to rule out obstructions of the
GI tract that would make passing feces difficult or impossible. To date we have not had any significant adverse side effects
and have not had to resort to manual disimpaction. In some cases enemas were given concurrently, thought this does not appear
to be necessary. There is always concern about giving PEG solutions to cats as oxidative injury to RBCs could occur, though
we have not documented this to date.