Medical Treatment
Medical management of animals with PSS includes correction of fluid,
electrolyte, and glucose imbalances and prevention of hepatic
encephalopathy by controlling precipitating factors. Dietary protein is
restricted to reduce substrates for ammonia formation by colonic
bacteria. Gastrointestinal hemorrhage, another source of protein, should
be controlled with ranitidine and sucralfate if gastric irritation or
ulceration is suspected, and with antihelmintics if parasites are
present. Non-absorbable intestinal antibiotics that are effective
against urea-splitting bacteria, such as Neomycin, should be
administered to decrease bacterial populations. Enemas and cathartics
may be used to reduce colonic bacteria and substrates and are especially
important in animals with hepatic encephalopathy. Lactulose, a
synthetic disaccharide, is hydrolyzed in the colon to organic acids
which increase fecal water loss osmotically and acidify colonic
contents. Acidification will trap ammonia as ammonium in the colon and
will alter colonic bacterial flora. Alteration of intestinal transit
time associated with the osmotic diarrhea will decrease time available
for ammonia production and absorption. Lactulose may be given orally or
by enema; dosages should be regulated so that feces is soft but formed.
Cystitis should be treated with appropriate antibiotics based on urine
culture and sensitivity; response may be poor if uroliths are present.
Urate uroliths may respond to low protein diets; renal calculi have
reportedly dissolved after shunt ligation.
With proper medical management, weight and quality of life stabilize
or improve with treatment in most animals. One third of dogs do well
with medical management as the sole method of treatment, with many
living to 7 years of age or older. Duration of survival with medical
management alone has been correlated to age at initial signs and with
BUN concentration; dogs that are older at presentation or have a higher
BUN live longer. Over half of dogs treated with medical management alone
are euthanized, usually within 10 months of diagnosis, because of
uncontrollable neurologic signs and, in some cases, progressive hepatic
fibrosis and subsequent portal hypertension. Surgery is therefore
considered to be the treatment of choice for animals with congenital
PSS.
Anesthetic Treatment
Anesthetic agents which are metabolized by the liver (i.e.
barbiturates and phenothiazine tranquilizers), highly protein-bound
(i.e. diazepam and barbiturates) or hepatotoxic (i.e. halothane) should
be avoided because of poor hepatic function and hypoalbuminemia. Mask
induction and maintenance of anesthesia with isoflurane is often the
anesthetic regimen of choice. Opioids can be used as a premedication
since it is reversible. Intraoperative treatment with plasma,
hetastarch, antibiotics, and steroids may be necessary.