Page 604 - Small Animal Internal Medicine, 6th Edition

576 PART IV Hepatobiliary and Exocrine Pancreatic Disorders

Treatment and Prognosis of the nonhematopoietic tumors. No predisposing factors
Treatment is supportive because there is no specific antiamy- have been identified except possibly primary copper storage
VetBooks.ir loid medication. Colchicine is of uncertain efficacy and is not disease (Hurwitz et al., 2014). In cats, in contrast to dogs,
benign tumors are more common than malignant tumors;
indicated for cats because of its potential toxicity. Instead,
the focus should be on reducing or eliminating the underly-
other diseases.
ing inflammatory disorder driving the amyloid deposition they are frequently an incidental finding during workup for
and supportive care with antioxidants and vitamin K supple- An unusual benign tumor occasionally found in cats is
mentation as necessary (0.5 mg/kg SC or IM every 7-20 the myelolipoma, which has a suggested association with
days). Blood transfusions may be necessary in cats with acute chronic hypoxia and hepatic involvement in diaphragmatic
hemoabdomen. The long-term prognosis is poor, and most hernias. Biliary carcinomas are the most common malignant
cats die as a result of intraabdominal bleeding. tumors in cats, which may mirror the high prevalence of
biliary tract disease in this species. Trematodes are also a
predisposing cause in humans and possibly in some cats,
FELINE COPPER STORAGE DISEASE but bile duct carcinomas also occur in cats outside the
range of liver fluke infestations, so there are other factors
Primary and secondary accumulation of copper is much less involved. Also in contrast to dogs, primary hepatobiliary
common in feline liver disease than in dogs (see Chapter 36), tumors are more common than metastatic neoplasia in
however, it has been reported (Whittemore et al., 2012; cats. Secondary tumors include particularly hematopoietic
Hurwitz et al., 2014). It is therefore important to consider tumors, such as lymphoma and, less commonly, leukemias,
staining feline liver biopsies for copper. histiocytic tumors, and mast cell tumors, as well as metas-
Primary copper storage disease has been reported in cats tases from other organs (e.g., pancreas, mammary glands,
with typical centrilobular distribution of copper on histology gastrointestinal tract). Hemangiosarcomas in the liver may
and a high dry weight concentration of copper on analysis be primary or secondary, and sometimes the origin is dif-
of liver (Hurwitz et al., 2014). Affected cats can be any sex ficult to ascertain if multiple organs are involved, although
or breed but tended to be young (median 2 years). Clinical, primary hepatic hemangiosarcomas appear to be more
clinicopathologic, and imaging findings overlap other feline common in cats than in dogs.
hepatobiliary disorders, particularly cholangitis. All cats had The common feline primary liver tumors recognized and
elevated ALT and, in some affected cats, the elevation was their behavior are outlined in Table 35.4.
marked. Diagnosis was on the basis of histopathology and
on measurement of copper > 700 µg/g of liver sample dry Clinical Features
weight. Cats were treated with a low copper diet (Prescrip- Primary malignant tumors of the liver are usually seen in
tion Diet L/D Feline Hepatic Health, Hills Pet Nutrition Inc, older cats (mean age, 10-12 years), and there is no obvious
Topeka, Kansas or Veterinary Diet Feline Hepatic, Royal gender predisposition reported. The presenting clinical signs
Canin, St Charles, MO.) and chelation with penicilliamine and clinicopathologic findings are indistinguishable from
10 to 15 mg/kg per os every 12 hours. Close monitoring is those in cats with other types of primary liver diseases. There
necessary because one cat developed hemolytic anaemia may be lethargy, vomiting, weight loss, ascites, or jaundice.
during treatment, which resolved with cessation of penicil- Some affected cats may have palpable hepatomegaly, ascites,
lamine. Alternatively, elemental zinc (2-4 mg per os every 24 or liver masses on abdominal palpation. However, at least
hours) could be used instead of chelation, although the rela- 50% of cats with liver tumors are asymptomatic.
tive efficacy is unclear. It is important not to use zinc concur-
rently with penicillamine as zinc will compete with the Diagnosis
copper for chelation. Administration of antioxidants is also Diagnosis relies on a combination of diagnostic imaging,
wise (vitamin E and SAMe). cytology, and histology. A suspicion may be gained from the
clinical findings, but given that more than half of affected
cats have no clinical signs, the liver mass may be a seren-
NEOPLASIA dipitous finding while the cat is being evaluated for another
reason. On clinical pathology, high liver enzyme activity
Etiology and bile acid concentration and mild anemia and neutro-
Primary liver tumors are uncommon in cats but appear to philia are common but nonspecific findings. Jaundice is
be more common than in dogs. Hepatic tumors are much uncommon but can occur. Liver function is usually normal
less common in both species than in humans, possibly because the tumor must involve more than 70% of the liver
because two of the predisposing factors for development mass before resulting in a reduction in liver function. The
of liver tumors (hepatitis virus infection and α-protease exception to this is a diffuse hematologic malignancy (e.g.,
inhibitor deficiency) have not been recognized in small lymphoma), which can result in a significant disturbance of
animals. Cirrhosis also predisposes to liver tumors in hepatocyte function (including coagulopathies). The func-
humans but is rare in cats. Liver tumors represent 1% to tional defects often resolve when the tumor is cytoreduced
3% of all neoplasms in cats (Liptak, 2007) but up to 7% by chemotherapy.