Page 434 - Problem-Based Feline Medicine

426 PART 7 SICK CAT WITH SPECIFIC SIGNS

energy must be restricted 50–75% for at least hepatic lipidosis. Histologic confirmation is the pre-
2 weeks to induce hepatic lipidosis. ferred modality, as recent reports have noted poor cor-
● Hepatic lipidosis occurs either as a primary idio- relation between cytologic interpretation and histologic
pathic event or secondary to another disease findings in cats with liver disease.
process. Frequently it occurs secondary to underly-
Histopathologic confirmation requires specialized pro-
ing diseases, most commonly cholangiohepatitis,
cessing to assess.
inflammatory bowel disease, and acute or chronic
● Both hematoxylin/eosin and specific staining for fat
pancreatitis. A recent study for 30% of cats had
should be performed.
acute pancreatitis.
● Greater than 50% of hepatocytes contain lipid vac-
● Acquired carnitine deficiency may be related to the
uolation.
development of hepatic lipidosis. Carnitine is pri-
marily synthesized in the liver and is essential for Abdominal ultrasonography may suggest hepatic lipi-
enzyme-mediated uptake of fatty acids into mito- dosis versus extrahepatic biliary obstruction, cholan-
chondria. In health, it also facilitates fatty acid giohepatitis and neoplasia.
product transport and the oxidation of long-chain ● Cats with hepatic lipidosis have diffuse hyper-
fatty acids. Starved cats have diminished capacity echogenicity, hepatomegaly, and an absence of bil-
for fatty acid beta-oxidation or export of VLDL, iary tract abnormalities.
leading to hepatic triglyceride sequestration.
Non-regenerative anemia is seen in 30% of cats.
● Less commonly observed in association with dia-
betes mellitus and toxicity (e.g., aflatoxins, bacter- Biochemical liver parameters are often suggestive of
ial toxins). hepatic lipidosis.
● Marked but discrepant increases of serum ALP in
Fat accumulation in hepatocytes results in cholestasis
comparison to ALT and AST.
and hepatic jaundice.
● Total bilirubin values exceed 2 mg/dl as most cats
Progressive liver dysfunction causes anorexia, vomiting are severely jaundiced.
and dehydration.
Approximately 30% of cats are hypokalemic.
Signs of overt hepatic encephalopathy (ptyalism,
Abnormal coagulation tests are observed in > 50% of
seizures) are uncommon.
cats. Approximately 20% have clinical evidence of
excessive bleeding. Vitamin K deficiency is the most
Clinical signs common coagulation abnormality.
● Carefully appraise coagulation status prior to liver
Most commonly seen in middle-aged to older cats of
aspirate or biopsy.
either sex. There is no breed predisposition.
The most common early signs are progressive anorexia
Differential diagnosis
and depression with intermittent vomiting over several
weeks. Cats with inflammatory liver disease (cholangiohepati-
tis) are often febrile and may have ascites. Increased
Common presenting complaints include, weight loss,
ALT +/− AST and hyperglobulinemia are prominent
prolonged (> 2 weeks) anorexia, vomiting and lethargy.
features in these cats and are not observed in cats with
Jaundice, hepatomegaly and dehydration are detected hepatic lipidosis.
on physical examination.
Sonographic abnormalities to the biliary excretory
Ascites, fever and ptyalism are uncommon. pathway or hepatic parenchyma are evident in most
cats with extrahepatic biliary obstruction and neopla-
sia, respectively.
Diagnosis
Cytologic examination of hepatic parenchyma obtained
Treatment
via fine-needle aspirate, or histologic examination of
a liver biopsy specimen is usually diagnostic for Cats must be fed 65–90 kcal/kg/day until eating.