Case Reports
J Vet Intern Med 2005;19:765–767
Acquired Portosystemic Shunting in 2 Cats Secondary to
Congenital Hepatic Fibrosis
Maurice M.J.M. Zandvliet, Viktor Szatmári, Ted van den Ingh, and Jan Rothuizen
C
ase 1. A 2-year-old female crossbred cat was referred
to Utrecht University Companion Animal Clinic with
a 2-month history of episodic vomiting, constipation, decreased appetite, apathy, and decreased activity. The vomiting was treated successfully with cisapride (0.25 mg/kg
PO q8h).
Physical examination disclosed no abnormalities and a
full CBC and serum biochemistry tests were performed.
These evaluations showed a leukocytosis (18.6 3 109/L;
reference range, 4.3–16.2 3 109/L), increased bile acid concentration (132 mmol/L [53.88 mg/mL]; reference range, 1–
13 mmol/L) and a low BUN concentration (3.6 mmol/L
[10.08 mg/dL]; reference range, 6.1–12.8 mmol/L). The
combination of high bile-acid concentration and low BUN
concentration indicated possible portosystemic shunting.
Fasting venous blood ammonia concentration was measured
and was increased (196 mmol/L [354 mg/dL]; reference
range, ,50 mmol/L). Abdominal ultrasonography was performed for the further diagnosis and identification of portosystemic shunting.
Abdominal ultrasonography revealed several small cortical cysts in both kidneys compatible with polycystic kidney disease (PKD). Otherwise, the size and structure of
both kidneys and the liver were considered normal. An
anomalous tortuous vessel with hepatofugal flow was seen
originating from the portal vein in the region where the
splenic vein enters the trunk of the portal vein. It was not
possible to follow the shunting vessel to its termination.
The direction of blood flow was hepatofugal in the portal
vein cranial to the origin of the anomalous vein and was
hepatopetal caudal to it. The left ovarian vein was dilated.
A very small amount of free abdominal fluid was seen. The
spleen was ultrasonographically normal. The tortuous
anomalous vein was suspected to be an acquired portosystemic collateral, therefore ultrasound-guided core biopsiesa
of the liver were taken.
The liver biopsies were processed routinely and stained
with hematoxylin-eosin, Von Gieson, and a reticulin stain
according to the method of Gordon and Sweet. Histological
From the Department of Clinical Sciences of Companion Animals
(Zandvliet, Szatmári, Rothuizen) and the Department of Pathobiology,
Division of Pathology (van den Ingh), Faculty of Veterinary Medicine,
Utrecht University.
Reprint requests: Maurice M.J.M. Zandvliet, DVM, MVR, Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 8, 3584 CM Utrecht, The
Netherlands; e-mail: M.M.J.M.Zandvliet@vet.uu.nl.
Submitted January 20, 2005; Revised March 18, 2005; Accepted
May 9, 2005.
Copyright q 2005 by the American College of Veterinary Internal
Medicine
0891-6640/05/1905-0019/$3.00/0
examination identified extensive fibrosis in the portal areas
with porto–portal bridging (Fig 1). In these fibrotic portal
areas, an increased number of cross-sections of abnormally
shaped bile ductules were found together with a few crosssections of hepatic arteries and the absence of recognizable
portal vein branches. Small focal infiltrates of lymphocytes
were also seen. The liver parenchyma and hepatic veins
showed no abnormalities. The histologic diagnosis was congenital hepatic fibrosis, a manifestation of congenital polycystic disease found in cats,1 which was compatible with
the previously detected renal cysts. The histologic changes
in the liver made the presence of portal hypertension a logical consequence and it was concluded that the shunting
vessel was acquired. Supportive therapy consisting of a
low-protein diet and lactulose was initiated.
Case 2. A 2½-year-old female Persian cat was presented
at Utrecht University Companion Animal Clinic with a history of weight loss despite good appetite and episodic neurologic signs consisting of ptyalism, decreased mentation,
and ataxia. Results of general physical and neurological examinations were normal. Based on the episodic signs of
decreased mentation and ataxia, a central neurological problem was anticipated. Laboratory examinations were performed to identify metabolic causes. Results included increased plasma fasting bile acid (114 mmol/L [46.53 mg/
mL]) and fasting ammonia (.286 mmol/L [.516 mg/dL])
concentrations and low BUN concentration (4.5 mmol/L
[12.60 mg/dL]). A tentative diagnosis of hepatic encephalopathy was made. An ultrasonographic examination of the
abdominal cavity and the liver was performed.
Ultrasonographic examination disclosed a small liver
with irregular structure. The left kidney was slightly smaller
(3.5 cm long) and the right kidney slightly larger (4.5 cm
long) than normal. Multiple small cysts compatible with
PKD were found in both kidneys. A connecting blood vessel was found between the portal vein and the hepatic region of the caudal vena cava. Due to the small size of the
liver, it was impossible to determine whether the shunting
vessel was located inside or outside of the liver. Ultrasonographic examination identified no other abnormalities,
and the conclusion was that the cat presumably had both a
congenital portosystemic shunt and PKD.
Because PKD had not resulted in measurable decompensation of renal function, surgical ligation of the shunt was
considered the preferred treatment. Intraoperative ultrasonography2 confirmed the presence of an intrahepatic portosystemic shunt, which then was completely closed by ligation with polyester suture materialb.
Recovery was unremarkable and a postoperative evaluation was performed after 1 month. At that time, the blood
ammonia concentration was high (202 mmol/L [364.62 mg/
dL]). Ultrasonographic examination of the abdominal cav-
766
Zandvliet et al
Fig 1. Photomicrograph of the liver biopsy from cat 1 showing extensive portoportal bridging fibrosis with multiple abnormally shaped
bile ductules (hematoxylin-eosin).
Fig 2. Photomicrograph of the liver biopsy from cat 2 showing portoportal bridging fibrosis with slightly dilated irregularly formed bile
ductules (hematoxylin-eosin).
ity identified an extrahepatic portosystemic shunt arising
from the portal vein at the point where the splenic vein
enters the portal vein. The left ovarian vein was not dilated
and a small amount of anechoic ascitic fluid was seen. Because this anomalous extrahepatic vein was not present before surgery, it was thought to be an acquired portosystemic
collateral, and a percutaneous ultrasound-guided liver biopsy was taken to determine the underlying cause of the
portosystemic shunting.
The liver biopsies were processed routinely and stained
as described above. Histologic evaluation of the liver biopsy revealed marked portal fibrosis and dilated, irregularly
formed bile ductules (Fig 2). No inflammatory cells were
present in the portal areas, but an occasional lymphocyte
and necrotic hepatocyte were observed in the limiting plate.
The final diagnosis was congenital hepatic fibrosis compatible with congenital polycystic disease in cats as well as a
mild degree of periportal hepatitis.
On the basis of these results, it was concluded that the
cat had 2 different congenital abnormalities, a congenital
portosystemic shunt and congenital hepatic fibrosis. Supportive therapy consisting of a low-protein diet and lactulose was started.
Portosystemic shunting can be due to a congenital portosystemic shunt with an intrahepatic or extrahepatic localization or to multiple acquired portosystemic collaterals resulting from portal hypertension, which in most cases is
due to primary hepatic disease. In order to identify the
cause of portosystemic shunting, a thorough ultrasonographic examination of the abdominal cavity, liver, and portal vein by an experienced radiologist is essential because
these results determine therapy and prognosis.
A congenital portosystemic shunt is amenable to surgical
ligation, whereas acquired portosystemic collaterals should
be managed medically by dietary measures (low-protein
diet) and lactulose. In the case of acquired shunting, it is
important to diagnose the underlying hepatic or vascular
lesion in order to identify whether it can be treated medically (e.g., cholangitis in cats) or surgically (e.g., arteriovenous fistula).
Portosystemic shunting results in portal blood bypassing
the liver and decreased hepatic clearance of substances
from the portal circulation. Increased concentrations of bile
acids, ammonia,3 and endotoxins4 can be measured in the
systemic circulation. Decreased urea concentration is due
both to decreased hepatic uptake and metabolism of ammonia and increased renal losses due to polyuria, often associated with portosystemic shunting.5 Increased systemic
endotoxin concentrations may result in a systemic inflammatory response and leukocytosis and induce vomiting by
stimulation of the chemoreceptor trigger zone.
Polycystic kidney disease is a well-described disease in
cats,6 especially in Persian cats.7 In this breed, it is an autosomal dominant trait8,9 due to a mutation in the PKD1
gene.10 The phenotype can be detected early in life by
means of ultrasound examination of the kidneys from as
young as 6–8 weeks of age, but cysts can arise at a later
age.8 The cysts originate from both the proximal and distal
tubules and can be found in both the renal cortex and medulla. The disease is progressive, and both the size and
number of cysts can increase over time and may result in
chronic renal failure later in life.9 PKD can be diagnosed
by means of ultrasonographic examination of the kidneys
once the cysts are of sufficient size or by kidney biopsy
that may show lesions suggestive of PKD at an earlier
stage. The pathogenesis of the disease is unknown, but in
humans, partial or complete obstruction of tubules is hypothesized.11 Structural abnormalities of the tubular basement membrane is another possibility that has been suggested in the literature.12
Less well known is that PKD in most cats is associated
with congenital biliary cystic lesions, either as multiple
large cysts (adult-type polycystic disease) or as congenital
hepatic fibrosis, characterized by portoportal bridging fibrosis and abnormally structured cystic bile ductules.1,13 The
hepatic lesions can be found both with or without lesions
in the kidney both in humans14 and in cats.3 It is therefore
more appropriate to refer to this disorder as polycystic disease and consider the kidney and liver lesions as 2 distinct
manifestations. The renal form (PKD) is the more common
PSS Due to Congenital Hepatic Fibrosis
variant in cats and most commonly associated with clinical
disease. The observed hepatic fibrosis causes portal hypertension and may result in the formation of acquired portosystemic collaterals.
In this case report, we describe 2 cats with polycystic
disease and signs attributable to portosystemic shunting
rather than to renal disease. Acquired portosystemic shunting is a rare event in cats, in contrast with dogs. To our
knowledge, these cats represent the first report of acquired
portosystemic collaterals due to congenital hepatic fibrosis
as a manifestation of polycystic disease in cats. In accordance, the clinical signs in these cats were those of hepatic
encephalopathy.
A second unusual observation is that cat 2 had 2 congenital disorders, a congenital intrahepatic portosystemic
shunt and congenital polycystic kidney and liver disease.
The presence of a congenital portosystemic shunt prevented
development of portal hypertension, and ligation of the congenital shunt resulted in portal hypertension due to preexisting hepatic fibrosis and formation of an acquired portosystemic collateral circulation. The combination of a congenital and an acquired shunt in 1 animal has been reported
in the dog,15 but ours is the first report in a cat. To the
authors’ knowledge, no causative relation exists between
these 2 congenital diseases, and the combination is thought
to be purely coincidental.
On the basis of these 2 cases, it seems advisable to examine liver histology in Persian cats and crossbred cats in
the presence of hepatic encephalopathy. Even if the only
ultrasonographic lesion is a congenital portosystemic shunt,
the cat should be evaluated for the potential presence of
hepatic fibrosis to prevent unnecessary surgical intervention.
Footnotes
Pro-Mag 2.2L biopsy system, Manan Medical Products, Northbrook,
IL, and ACNy Biopsy Needle (16 G 3 16 cm), Med-Tech Inc,
Gainesville, FL
b
Ethibond Excel 2/0, Ethicon, Johnson & Johnson Intl, Hamburg, Germany
a
767
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