Page 590 - Small Animal Internal Medicine, 6th Edition

562 PART IV Hepatobiliary and Exocrine Pancreatic Disorders

TABLE 35.1 obese animals, and the clinical signs are complicated by
those of the concurrent disease. For example, the clinical
VetBooks.ir Clinically Relevant Hepatobiliary Diseases in Cats signs of acute diabetic ketoacidosis are similar to those of
developing hepatic lipidosis.
PRIMARY
SECONDARY
Clinical signs are typical of an acute (reversible) loss of
hepatocyte function and of hepatocyte swelling, with resul-
Common tant intrahepatic cholestasis. Cats are usually jaundiced and
Idiopathic lipidosis Secondary lipidosis have intermittent vomiting and dehydration. They may also
Neutrophilic cholangitis Hyperthyroidism have diarrhea or constipation. There is usually palpable hep-
Lymphocytic cholangitis Pancreatitis atomegaly on physical examination. HE, most often mani-
Diabetes mellitus fested as depression and ptyalism, is related to severe
hepatocellular dysfunction and relative arginine deficiency
Uncommon or Rare to which the anorexic cat is predisposed. Previously obese
Congenital portosystemic Secondary neoplasia (less cats have extensive loss of muscle mass but maintain certain
shunt common than primary) fat stores, such as those in the falciform ligament and ingui-
Extrahepatic bile duct Biliary stasis associated nal region (Fig. 35.2).
obstruction with extrahepatic sepsis
Liver flukes (except common Hepatic abscess Diagnosis
in hunting cats in endemic The only truly definitive and reliable method of diagnosing
areas) and identifying concurrent and causative conditions is his-
Primary neoplasia topathology of a wedge biopsy of liver obtained at laparot-
Infections (see Box 35.5) omy or laparoscopy or (less reliably) a Tru-Cut-type biopsy
Drug- or toxin-induced taken under ultrasonographic guidance. However, all of
hepatopathy these procedures require a general anesthetic, and most cats
Biliary cysts with hepatic lipidosis are too ill on presentation to be safely
anesthetized. Therefore using fine-needle aspiration (FNA)
Sclerosing cholangitis/biliary cytology of the liver performed blindly or under ultrasono-
cirrhosis graphic guidance in an awake or sedated cat can yield a
Congenital ductal plate preliminary diagnosis; this will allow intensive management
abnormalities and tube feeding for a few days to stabilize the patient before
Primary copper-associated anesthesia is considered for a more definitive diagnosis.
hepatopathy Because coagulopathies are common in cats with lipidosis, a
Hepatic amyloidosis few days of therapy will help correct them before considering
Intrahepatic arteriovenous surgery. The clinician must be aware, however, that FNA
fistula cytology, although useful for emergency diagnosis and man-
agement, can be misleading in cats, and hepatic parenchymal
disease can be misdiagnosed as lipidosis using this tech-
disease and even in cats with a normal or thin body condi- nique. In addition, concurrent diseases of the liver and other
tion. Any anorexic cat with concurrent disease must there- organs, including the pancreas and small intestine, will be
fore be regarded as being at high risk of hepatic lipidosis, and overlooked without a laparoscopic or surgical biopsy. It is
appropriate feeding support should be instituted as rapidly important to differentiate mild to moderate lipid accumula-
as possible. Secondary lipidosis may occur in association tion in hepatocytes, which is common in sick and anorexic
with any disease causing anorexia, but has been most com- cats and causes no clinical problems, from clinically severe
monly recognized in cats with pancreatitis, diabetes mellitus lipidosis on cytology (see Fig. 35.1).
(DM), other hepatic disorders, IBD, and neoplasia. FNA can be performed under ultrasonographic guidance
while the cat is being evaluated or obtained blindly if there
Clinical Features is palpable hepatomegaly. The procedure is performed in a
Most affected cats are middle-aged, but they can be of any similar way to aspiration of a mass. The enlarged liver is
age or sex. In a recent study from Israel, 99% of affected cats palpated, and the abdominal wall overlying it is clipped and
were neutered and 66% were female (Kuzi et al., 2017). There prepped. A 22-gauge needle is passed through the skin into
is no reported breed predilection. Cats with primary lipido- the liver from ventrally on the left side, which prevents inad-
sis are commonly obese, are housed indoors, and have expe- vertent puncturing of the gallbladder, and gentle suction is
rienced a stressful event (e.g., introduction of a new pet into applied to a 5-mL syringe two or three times, before with-
the household, abrupt dietary change) or an illness that has drawing and gently expressing the needle contents onto a
caused them to become anorexic and lose weight rapidly. The slide (see Fig. 34.14). Analgesia is recommended for either
initiating event is not always known. Secondary lipidosis procedure because puncture of the liver capsule is painful.
may affect cats of normal or thin body condition as well as Opiate partial agonists, such as buprenorphine, are a good