Page 1125 - Small Animal Clinical Nutrition 5th Edition

Hepatobiliary Disease 1171

protein deficiency may play a major role in the development of DM taurine. Although no minimum recommended allowances
VetBooks.ir feline idiopathic hepatic lipidosis. Cats with hepatic lipidosis for taurine for healthy dogs have been defined, foods for dogs
with liver disease should contain at least 0.1% DM taurine.
have signs of protein malnutrition include hypoalbuminemia,
Appropriate amounts of high quality dietary protein are also
anemia, muscle wasting and negative nitrogen balance (Biourge
et al, 1994; Barsanti et al, 1977). Specific amino acids (e.g., important in patients with chronic hepatitis and/or cirrhosis,
methionine and arginine) become limiting during fasting in portal hypertension and dogs with copper-associated hepato-
obese cats (Biourge et al, 1994). Protein or amino acid deficien- toxicosis. Hypoalbuminemia, which reflects depleted body
cy may induce lipid accumulation in the liver by limiting stores and reduced protein synthesis, is a frequent and serious
lipoprotein synthesis needed for normal lipid metabolism and problem in patients with chronic liver disease. Protein plays a
transport (Biourge et al, 1994). Protein supplementation at only leading role in hepatic regeneration; therefore, patients with
one-fourth of the daily requirement (22 g protein/day) signifi- liver disease require adequate protein intake to remain anabolic
cantly reduced lipid accumulation in the liver and promoted and support regeneration of hepatocytes. On the other hand,
positive nitrogen balance during long-term fasting in obese cats dietary protein restriction may be important in patients with
(Biourge et al, 1994a). endstage cirrhosis,hyperammonemia and HE.Protein,or more
Cats with hepatic lipidosis will usually tolerate moderate accurately, nitrogen excess, is a major contributor to neurotoxic
amounts of dietary protein unless they are suffering from con- precursors formed when amino acids are metabolized to
current HE, which is uncommon. Commercial veterinary ther- ammonia. For patients with liver disease, the goal is to provide
apeutic foods containing 30 to 45% DM protein are well toler- adequate dietary protein to support hepatic regeneration while
ated by cats with hepatic lipidosis and have been used success- avoiding excess dietary protein that might contribute to HE.
fully in many cases. Protein needs for cats with cholangitis are The protein requirements for patients with PSS have been
similar to those for cats with hepatic lipidosis. roughly estimated from a nutritional study in adult dogs with
Adult cats and ferrets developed hyperammonemia and HE surgically created shunts (Laflamme et al, 1993). This study
when fed foods devoid of arginine (Boxes 68-1 and 68-2). showed that ingestion of 2.11 g crude protein/kg body
Foods for cats with hepatic lipidosis should provide adequate weight/day with an 80% or greater availability was adequate to
arginine. Arginine levels in food should always be above the maintain body protein reserves without producing HE. In the
minimum dietary allowance for adult maintenance (≥0.77% absence of other data, this recommendation for dietary protein
DM [NRC, 2006]). More arginine is required in cat foods that intake seems appropriate. This equates to approximately 14 to
contain more than 20% DM protein (NRC, 2006). Arginine 16% protein calories (15 to 20% DM protein) for dogs and 25
levels in foods for cats with liver disease should be between 1.5 to 30% protein calories (30 to 35% DM protein) for cats.These
to 2.0% DM. Good quality commercial foods are typically ade- protein levels are also appropriate for dogs and cats with most
quate in arginine. Homemade vegetable-based foods and hu- other forms of liver disease, except hepatic lipidosis (described
man enteral foods fed to cats with encephalopathic clinical above) and HE. Patients with evidence of HE will often need
signs should be supplemented with arginine. restricted dietary protein levels for the short term (10 to 15%
Ensuring adequate taurine intake is important for anoretic DM for dogs and 25 to 30% DM for cats). For a point of ref-
cats with hepatic lipidosis. Cats and dogs primarily synthesize erence, the minimum recommended protein allowances for
taurine in the liver and bile salts are mainly conjugated with foods for normal adult dogs and cats are 10 and 20% DM,
taurine. Compared to cats, dogs have a high capacity to synthe- respectively (NRC, 2006).
size taurine; therefore, dietary taurine is usually not essential. In addition to the absolute amount of protein fed, the amino
Food-induced bile salt excretion into the gut can result in sig- acid profile and digestibility are important for optimal protein
nificant loss of taurine, particularly when normal enterohepatic usage. Amino acids from poor-quality protein sources are de-
recycling is interrupted. Taurine synthesis is limited in cats; aminated and metabolized to a greater extent than amino acids
therefore, dietary taurine is essential. Adequate taurine nutrit- from higher quality protein sources and exacerbate hyperam-
ure is important in patients with enterohepatic circulation monemia. Intestinal bacteria may degrade poorly digested pro-
abnormalities and possibly in liver disease. In certain species, teins and add to the body’s ammonia burden.
taurine also stimulates synthesis and turnover of bile independ- The importance of the dietary protein source has been stud-
ent of its role as a bile acid conjugate. Taurine appears to aid ied in human patients with HE and in several experimental
choleresis in dogs and possibly cats. This role may explain the studies in dogs with PSS (Center, 1996b). Vegetable and dairy
observation that taurine prevents cholestasis in certain models protein sources have produced the best results in maintaining
of liver disease. Most commercial cat foods and foods for stress positive nitrogen balance with minimal encephalopathic signs
and recovery for dogs and cats are fortified with taurine. in human patients with liver disease (Uribe, 1990; Bianchi et al,
However, homemade and human enteral foods fed to cats 1993; Weber et al, 1985). Foods containing soybean meal avert-
should be supplemented with taurine (250 to 500 mg/day) ed encephalopathic signs in dogs with experimentally created
(Chapter 10). The minimum recommended allowance for dry shunts (Center et al, 1997; Thompson et al, 1986; Schaeffer et
expanded and moist foods for adult cats is 0.10 and 0.17% DM, al, 1986). In addition, dairy products (especially cottage cheese)
respectively (NRC, 2006). Foods for cats with hepatic lipidosis have been recommended for use in homemade foods for dogs
and other liver diseases should probably contain at least 0.3% and cats with PSS and chronic hepatic insufficiency (Center,