Page 591 - Small Animal Internal Medicine, 6th Edition

CHAPTER 35 Hepatobiliary Diseases in the Cat 563

TABLE 35.2
VetBooks.ir Important Differences Between Cats and Dogs With Hepatobiliary Disease REASON FOR DIFFERENCE

CATS
DOGS
PARAMETER
Disease spectrum Cats have a higher prevalence of Chronic parenchymal disease Unknown. It has been proposed
hepatobiliary diseases than is the most common, usually that the high prevalence of
dogs. progressing to fibrosis and biliary tract disease is caused
Chronic parenchymal disease, cirrhosis, with portal by differences in anatomy,
fibrosis, cirrhosis, and portal hypertension. but this has not been proved.
hypertension are much less Biliary tract disease (acute In most cats, the bile duct joins
common than in dogs. and chronic) does occur but the single major pancreatic
Concurrent biliary tract disease, is uncommon. duct before entering the small
pancreatitis, and inflammatory Secondary hepatic lipidosis intestine at the major
bowel disease are possible in can develop in association duodenal papilla, whereas in
either species but are more with other diseases but is most dogs the bile duct enters
common in the cat. Ascending not usually a clinical the duodenum separately
infections of the bile duct are problem. from two pancreatic ducts.
also proposed to be more Underlying cause of hepatic
common in cats. lipidosis in cats is not fully
Cats are particularly susceptible to elucidated (see text) but likely
clinically serious hepatic caused by differences in
lipidosis (primary or secondary). metabolism.
Ability to Cats have a relative deficiency of Because dogs are generally Cats are less likely than dogs to
metabolize drugs glucuronyl transferase, reducing more likely to scavenge, have toxic liver damage
or toxins their ability to metabolize drugs they may have more access associated with environmental
and toxins and making them to hepatotoxins. toxins. However, cats are
more susceptible to oxidant Dogs generally have no generally less able to
toxins. However, cats are deficiency of enzymes, but metabolize toxins than dogs
pickier with their food and there are some breed and are therefore more
therefore less likely to scavenge variations (e.g., Doberman susceptible than dogs to toxic
toxins. Pinschers that have an liver damage caused by
impaired ability to detoxify many potentially hepatotoxic
potentiated sulfonamides). drugs.
Isoenzymes of Cats do not produce a steroid- Dogs have a steroid-induced Even mild increase in ALP levels
alkaline induced isoenzyme of alkaline isoenzyme of ALP and ALP in cats suggests a significant
phosphatase phosphatase (ALP) and the that has a long half-life; the ongoing problem.
(ALP) and steroid half-life of ALP is very short in half-life of hepatobiliary ALP ALP level does not increase with
hepatopathies cats (6 hours). is 66 hours and the half-life steroid therapy (or HAC
Hyperadrenocorticism (HAC) is of glucocorticoid-induced before the development of
rare in cats. ALP is 74 hours. diabetes mellitus) in cats.
Hyperadrenocorticism is Steroid treatment and HAC are
common in dogs. major differentials for high
ALP levels in dogs.
Hepatic Adapted to high-protein diet— Adapted to use dietary starch; Cats will rapidly develop
metabolism of postprandial hepatic postprandial insulin release protein-calorie malnutrition
glucose and gluconeogenesis from protein results in glucose storage. and start breaking down their
protein and constantly high activity of Dogs can downregulate own body protein if fed a
protein catabolizing enzymes in hepatic protein, protein-restricted diet in liver
the liver, which cannot be metabolizing enzymes as disease.
downregulated. necessary when the diet is Arginine deficiency can
High dietary requirement for low in protein. contribute to the development
arginine for the hepatic urea Lower arginine requirement of hyperammonemia in cats
cycle. than cats. with liver disease if the cat is
Taurine is an essential dietary No obligate dietary taurine fed a diet deficient in
requirement, and bile salts are requirement provided diet arginine (e.g., dairy protein).
all conjugated with taurine. contains enough sulfur Taurine, arginine, and protein
amino acids. deficiency can contribute to
the pathogenesis of hepatic
lipidosis in cats.