LABORATORY EVALUATION OF LIVER DISEASE IN DOMESTIC ANIMALS

31 LABORATORY EVALUATION OF LIVER DISEASE IN DOMESTIC ANIMALS



1 What are the major types of inflammatory liver disease described in dogs?


Despite decades of study, the classification of canine inflammatory liver disease is poorly defined. Although many etiologic agents have been defined, a cause cannot be established for most cases of chronic hepatitis. The histopathologic classification of chronic liver disease is controversial. “Chronic hepatitis” is a general, all-inclusive categorization used by many clinicians. More specific terms include chronic progressive hepatitis, chronic active hepatitis, chronic lobular dissecting hepatitis, and cirrhosis.



2 List the known causes of acute hepatitis in the dog and cat.



a. Infectious: bacterial abscesses, cholangitis, cholangiohepatitis, canine adenovirus type 1, feline infectious peritonitis, histoplasmosis, toxoplasmosis

b. Drugs: thiacetarsemide, diethylcarbamazine, acetaminophen, mebendazole, halothane, methoxyflurane, aprinidine, ketoconazole, methotrexate, nalidixic acid, tetracycline, tolbutamide, trimethoprim-sulfadiazine, diazepam (cat)

c. Chemicals: carbon tetrachloride, dieldrin, chloroform, arsenic, chlorinated hydrocarbons, naphthalenes, chlorinated biphenyls, phosphorus, copper, mercury, iron, selenium, tannic acid


3 List the causes of chronic hepatitis in the dog.



a. Infectious: bacterial cholangitis or cholangiohepatitis, canine adenovirus type 1, leptospirosis, canine acidophil cell viral hepatitis, histoplasmosis, dirofilariosis

b. Drugs: primidone, phenytoin, phenobarbital, ketoconazole, methotrexate, milbolerone, methotrexate, trimethoprim-sulfadiazine, glucocorticoids

c. Copper accumulation disorders: Bedlington terriers, West Highland white terriers, Skye terriers, Doberman pinschers

d. Autoimmune disorders

e. Alpha-1-antitrypsin disorder


4 What are the major types of hepatitis described in cats?


Categorization of feline inflammatory liver diseases is controversial. Some authors prefer to use cholangitis or cholangiohepatitis to describe all inflammatory liver diseases. Other authors have used more specific categories, including lymphocytic portal hepatitis, lymphocytic cholangitis/cholangiohepatitis, suppurative cholangiohepatitis, chronic cholangiohepatitis, and sclerosing cholangitis. This categorization is complicated by evidence that lymphocytes accumulate in portal areas of aged cats.



5 What are the major clinical and laboratory abnormalities in acute hepatitis?


Clinical signs of acute hepatitis include anorexia, vomiting, icterus, and hepatic encephalopathy. A marked (>100-fold) increase in alanine transaminase (ALT) and aspartate transaminase (AST) is a consistent finding. Alkaline phosphatase (ALP) is moderately increased in the dog but may not increase or may increase only slightly in the cat. Gamma-glutamyltransferase (GGT) may remain within reference limits or increase slightly. If lesions are diffuse, liver dysfunction may occur, as detected by increased serum bile acids or serum bilirubin and sulfobromophthalein (BSP) retention. Serum albumin and globulin concentrations are usually within reference limits but may be increased if hemoconcentration is present. Dogs with acute hepatitis are predisposed to development of disseminated intravascular coagulopathy.



6 What are the major clinical and laboratory abnormalities associated with canine chronic hepatitis?


Frequent clinical signs of canine chronic hepatitis include weight loss, anorexia, mild to moderate nonregenerative anemia, polyuria, polydipsia, and decreased liver size. In late-stage hepatic failure, icterus, ascites, or signs of hepatic encephalopathy may develop. Leakage enzymes are variably increased. The magnitude of increase roughly correlates with numbers of hepatocytes that are being destroyed. The term chronic active hepatitis has been used to describe chronic hepatitis in which large increases in leakage enzymes persist over time. Consistent large increases in cholestatic enzymes are present, and the magnitude of increase in cholestatic enzymes exceeds the magnitude of increase in leakage enzymes. Hepatocellular dysfunction can usually be identified at initial diagnosis. Polyclonal gammopathy and mild nonregenerative anemia are usually present. In late-stage liver failure, hypoalbuminemia, increased serum ammonia concentrations, and hyperbilirubinemia may be present.



7 What are the major clinical and laboratory abnormalities associated with canine steroid hepatopathy?


Clinical signs of steroid hepatopathy are usually not seen in the dog, although signs of hyperadrenocorticism or a history of glucocorticoid administration should be present. Lesions in the liver are characterized by multifocal areas of hepatocellular vacuolar change. Intracellular lipid content may also be increased. Leakage enzymes may be mildly to moderately increased due to altered cell membrane permeability and enzyme induction. A marked increase in ALP is present in dogs. Tests of liver function are usually within reference limits.



8 What are the major clinical and laboratory abnormalities associated with congenital portosystemic shunting of blood?


Clinical signs of congenital portosystemic shunting include microhepatia, hepatic encephalopathy, and hypoglycemic coma in young dogs. Leakage and cholestatic enzymes are usually within reference limits. Baseline plasma ammonia and postprandial bile acids are usually abnormal.



9 What are the major clinical and laboratory abnormalities associated with feline suppurative cholangiohepatitis?


Suppurative cholangiohepatitis tends to occur in young and middle-aged cats. Clinical signs include severe illness characterized by lethargy, fever, vomiting, and icterus. Liver size may be normal, increased, or decreased. Laboratory findings include neutrophilia, left shift, hyperbilirubinemia (mean 4.7 mg/dl), moderate to marked increase in ALT, and little or no increase in cholestatic enzymes. As cholangiohepatitis becomes more chronic, neutrophilia and left shift may not be present, ALT tends to be lower, and cholestatic enzymes may increase.

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  4. METABOLIC ACID-BASE ABNORMALITIES

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Aug 26, 2016 | Posted by in INTERNAL MEDICINE | Comments Off on LABORATORY EVALUATION OF LIVER DISEASE IN DOMESTIC ANIMALS

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