Page 632 - Small Animal Internal Medicine, 6th Edition

604 PART IV Hepatobiliary and Exocrine Pancreatic Disorders

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A B

FIG 36.10
Typical small-breed dogs with congenital extrahepatic portosytemic shunts. (A) Eight-
month-old female Border Terrier. (B) Nine-month-old female Miniature Schnauzer.

A B

FIG 36.11
(A) Portovenogram in a 1-year-old Golden Retriever with an intrahepatic portosystemic
shunt. This was a central divisional shunt, which had a venous sinus–like structure, as
demonstrated well in this radiograph. (B) Normal portovenogram in a dog for comparison
with A. (Courtesy Diagnostic Imaging Department, Queen’s Veterinary School Hospital,
University of Cambridge, Cambridge, England.)
Clinical Features Chapter 33). Urate uroliths are also common and can be

Clinical signs are similar to those in cats; neurologic, GI, and cystic or renal. Anecdotally, urate renal calculi seem to be
urinary tract signs predominate (see Chapter 35 for more more common in terriers, and dogs presenting with calculi
details). About 75% of dogs present before 1 year of age, but often do not have prominent neurologic signs. On physical
some present at an older age, with some as old as 10 years examination, animals are often but not always smaller than
before signs are recognized. There is a spectrum of severity their litter mates and may have nonlocalizing neurologic
of neurologic signs, ranging from severely affected young signs and, in some cases, palpable renomegaly. The latter is
puppies that persistently circle, become centrally blind, and caused by circulatory changes and is not a reflection of renal
can even have seizures or become comatose, to very mildly disease or uroliths; it is of no clinical significance and
affected or asymptomatic individuals. It is likely that this regresses after shunt ligation. Other congenital defects may
variation reflects differences in shunt fraction and dietary be apparent, particularly cryptorchidism, which is reported
and other environmental differences among dogs. Concur- in up to 50% of male dogs with congenital PSSs.
rent inflammation is an important trigger for HE in affected
dogs, so clinicians should look carefully in affected animals Diagnosis
for inflammatory disease such as urinary tract infections. The diagnosis of congenital PSS in dogs is the same as in
PU-PD with hyposthenuric urine are relatively common; cats (see Chapter 35) and relies on visualizing the shunt-
this is probably multifactorial in etiology and partly caused ing vessel ultrasonographically, with computed tomogra-
by reduced renal medullar concentrating gradient (see phy (CT) angiography or portovenography (Fig. 36.11, or