Page 1112 - Small Animal Clinical Nutrition 5th Edition

1158 Small Animal Clinical Nutrition

blood clotting abnormalities may become clinically evident
VetBooks.ir during liver biopsy procedures or surgery. Icterus may be
observed with severe cholestasis. Acholic feces due to total bile
duct obstruction occur rarely in dogs and cats. Consequently,
serious disturbances in fat digestion and absorption, which rely
on functional biliary excretion, are rare in hepatobiliary disease
(Rothuizen and Meyer, 2000).
Neurobehavioral signs of HE develop in animals with por-
tosystemic vascular anomalies and a decreased functional liver
mass. Typical signs include aggression (cats) (Figure 68-2),
aimless wandering, manic barking (dogs), ataxia, lethargy, epi-
sodic weakness, ptyalism (cats especially), altered conscious-
ness (disorientation, stupor or rarely coma), head pressing
(Figure 68-3), sudden blindness, circling, pacing and seizures
(Center, 1995). These signs may be episodic and may be
linked to meals, dietary changes, GI hemorrhage or some
other event.
A normal liver can be difficult to palpate in dogs and cats; the
edges are normally sharp and the liver resides cranial to the
ribcage. Hepatomegaly, however, is readily palpated in most
cases. Hepatomegaly may be caused by passive venous conges-
tion, inflammation, neoplasia, nodular hyperplasia and infiltra-
tion by fat, amyloid or glycogen. On the other hand, reduced
liver size is difficult to palpate in dogs and cats. Abdominal
enlargement associated with ascites usually develops slowly and
Figure 68-1. A 14-year-old Persian cat with ptyalism due to liver insidiously. Small amounts of effusion may go undetected,
disease.
whereas moderate to severe abdominal effusion becomes obvi-
ous. Hyperadrenocorticism may also cause distention from ab-
dominal wall muscle weakness and hepatomegaly from steroid
hepatopathy.
When liver disease is included in the differential diagnosis
based on one or more of the historical or physical findings,
additional diagnostics are required. Figure 68-4 presents a
diagnostic algorithm for liver diseases.

Laboratory Evaluation
It is beyond the scope of a nutrition textbook to discuss in
detail, specific laboratory tests and imaging techniques (i.e.,
ultrasound, nuclear imaging techniques, laparoscopy) used to
detect and confirm hepatobiliary disease. Readers are referred
to small animal internal medicine, GI and surgical texts for
these details. However, routine tests that help establish param-
eters for developing feeding and reassessment plans are sum-
marized below.
Liver disease is most often discovered during hematologic,
Figure 68-2. An eight-month-old Himalayan cat with clinical signs of serum biochemistry and urine tests performed either as part
aggression associated with hepatic encephalopathy due to a con- of a routine wellness screen or diagnostic evaluation of sick
genital portosystemic shunt.
dogs and cats. Hematologic changes may include anemia,
abnormal erythrocyte morphology, reduced platelet numbers
weight loss. Bleeding tendencies (which are rarely noted clini- or function and detection of icteric or lipemic plasma (Center,
cally) may develop due to a decrease in hepatic production of 1995, 1996e; Dial, 1995). A regenerative anemia caused by
clotting factors, to consumption coagulopathy (disseminated blood loss due to GI hemorrhage and/or a bleeding diathesis
intravascular coagulation) (Rothuizen and Meyer, 2000) or may by present. More commonly, a nonregenerative anemia is
malabsorption of vitamin K, which is essential for production found and is associated with chronic disease, chronic blood
of vitamin K-dependent factors in patients with prolonged loss, malnutrition and reduced erythrocyte survival (Center,
extrahepatic bile duct obstruction (Center, 1995). Subclinical 1995, 1996e). Target cells, poikilocytes and spur cells, Heinz