Page 640 - Small Animal Internal Medicine, 6th Edition

612 PART IV Hepatobiliary and Exocrine Pancreatic Disorders

Arterioportal Fistula cavity, such as the endocardium, lung, or blood, may dis-
Intrahepatic arterioportal fistula, causing marked volume seminate to the liver, causing abscessation.
VetBooks.ir overload of the portal circulation and resulting in portal aerobic gram-negative organisms, particularly E. coli, which
The most common isolates in published studies are
hypertension, acquired PSSs, and ascites, is seen occasion-
can be multiresistant, and the anaerobic Clostridium spp.
ally. Abdominal Doppler ultrasonography can frequently
detect the tortuous tubular structures representing the con- Staphylococcus spp. have also been identified.
nection between an artery and overperfused portal vein or
veins; sometimes the turbulent blood flow through the fistula Clinical Features
can be auscultated through the body wall. If only one lobe The typical signalment and physical examination findings in
of the liver is affected, the lobe containing the arterioportal dogs with hepatic abscesses depend on the underlying cause.
fistula can be removed surgically. Assuming that there is Dogs older than 8 years are most often affected because
adequate intrahepatic portal vasculature, acquired PSSs the predisposing causes of liver abscesses are seen more
regress once portal overcirculation subsides. More often, commonly in older dogs. Regardless of the initiating event,
multiple liver lobes are involved, making surgical treatment anorexia, lethargy, and vomiting are consistent presenting
impossible. complaints. Expected physical examination findings include
fever, dehydration, and abdominal pain. Hepatomegaly may
be detected in dogs with diabetes mellitus or hyperadre-
FOCAL HEPATIC LESIONS
nocorticism and in some dogs with primary hepatobiliary
disease.
ABSCESSES
Diagnosis
Etiology
Neutrophilic leukocytosis with a left shift, with or without
Hepatic abscesses are usually the result of septic embolization toxic changes, and high serum ALP and ALT activities are
from an intraabdominal bacterial infection. In puppies they dependable but nonspecific clinicopathologic abnormalities.
are frequently a consequence of omphalophlebitis, whereas Survey abdominal radiographs may reveal evidence of an
in adult dogs they arise most often subsequent to inflam- irregular hepatomegaly, mass, or gas opacities within the
matory conditions of the pancreas or hepatobiliary system. area of the hepatic parenchyma (Fig. 36.15), but ultrasonog-
Adult dogs with certain endocrine diseases (e.g., diabetes raphy is the imaging modality of choice. One or more
mellitus, hyperadrenocorticism) are also at risk. Hepatic hypoechoic or anechoic hepatic masses and perhaps a hyper-
abscesses have also been reported secondary to liver fluke echoic rim surrounding the mass or masses are characteristic
infection in a dog (Lemetayer et al., 2016). Occasionally, findings. If there are multiple masses that would preclude
infection arising from a location other than the abdominal surgical removal, or if the owner declines surgery, FNA

A B

FIG 36.15
(A) Lateral abdominal radiograph of a 1-year-old female Great Dane with a liver abscess
(arrows) caused by Clostridium spp. The cause was undetermined. (B) Gross appearance
of the resected liver lobe containing an abscess (arrow).