Page 1130 - Small Animal Clinical Nutrition 5th Edition

1176 Small Animal Clinical Nutrition

(7 to 14 mg/kg body weight) also benefit weight loss, obesity (Meyer, 1998a). The same effect could not be reproduced by
VetBooks.ir prevention and hepatic lipidosis (Blanchard, 1998). Foods for feeding a BCAA-enriched food vs. an isonitrogenous control
food in dogs with HE. This finding may have been due to
cats with hepatic lipidosis should provide at least 0.02% DM
reduced consumption of the test diet, leading to a severe cata-
L-carnitine.
bolic state and increased endogenous ammonia production
Other Nutritional Factors (Meyer, 1998a). The primary positive effect of dietary and
Depending on the type of hepatobiliary disease, some of the intravenous BCAA enrichment may be the normalization of
following nutritional factors may also be important. nitrogen balance, rather than a direct effect on neurotransmit-
ter imbalances per se (Meyer, 1998a).
Carbohydrate
Patients with clinical evidence of HE should receive adequate Vitamins
carbohydrate intake. Studies suggest that feeding foods with a Vitamin deficiencies are common in patients with chronic
high carbohydrate component is advantageous (Zieve and hepatic disease. Deficient dietary intake and malabsorption are
Zieve, 1987). Providing at least 30 to 50% of dietary calories in the principal causes of vitamin deficiency, although decreased
the form of easily digested, complex digestible carbohydrate storage, metabolic defects and increased requirements also may
(e.g., corn, rice, wheat, barley) may help avert encephalopathic be involved (Marks et al, 1994).
clinical signs (Center, 1996b). Thus, the recommendations for Deficiency of water-soluble vitamins may occur due to inade-
DM digestible carbohydrates in foods for dogs and cats with quate intake,vomiting and urinary losses.Hepatic concentrations
liver disease are 45 to 55% and 30 to 40%, respectively. of folate, riboflavin, nicotinamide, pantothenic acid, pyridoxine
and vitamin B 12 are decreased in people with cirrhosis (Leevy et
Fiber al, 1982). Commercial pet foods usually contain sufficient quan-
Foods with increased dietary fiber levels may benefit patients tities of water-soluble vitamins to meet the needs of most
with hepatobiliary disease. Dietary fiber reduces the availabili- patients with liver disease. Supplementation with water-soluble
ty and production of nitrogenous wastes in the GI tract. vitamins is indicated in patients: 1) receiving aggressive diuretic
Although highly digestible foods were previously advocated to therapy for ascites, 2) with profound polydipsia and polyuria, 3)
maximize digestion and absorption and reduce colonic residues, with prolonged anorexia and 4) eating homemade foods.
considered a major source of encephalopathic toxins, this prac- Abnormal blood coagulation tests and excessive bleeding
tice is currently not recommended. Increased amounts of fer- reflect impaired hepatic synthesis, activation of clotting factors
mentable fiber encourage nitrogen fixation by enteric bacteria, and/or a consumptive coagulopathy. Vitamin K stores in the
resulting in reduced quantities of nitrogenous substances avail- liver are limited and can be rapidly depleted when dietary
able for absorption. Increased dietary fiber may bind noxious sources are inadequate or lipid (and therefore fat-soluble vita-
bile acids, endotoxins and other bacterial products. Dietary min) malabsorption is severe. Among other functions, vitamin
fiber is also useful in maintaining euglycemia (Chapter 29) and K catalyzes the activity of several clotting factors and normally
altering the pH of colonic contents. Total dietary fiber levels is recycled in the healthy liver back to its active form (this step
should be between 3 and 8% and be primarily soluble fiber. of vitamin K metabolism is sensitive to inhibition by dicumarol).
However, pet food labels and available product information list Vitamin K deficiency may develop in patients with hepato-
fiber content as crude fiber rather than total dietary fiber. Crude biliary disease for several reasons. Oral antibiotic therapy may
fiber analyses do not represent the soluble or fermentable fiber destroy the intestinal microflora that normally synthesize vita-
content of foods. Thus, for all practical purposes, this recom- min K. Chronic bile duct obstruction can interfere with entero-
mendation cannot be readily evaluated. Crude fiber levels in hepatic circulation of bile acids causing intestinal bile acid defi-
combination with knowledge of the soluble content of the fiber ciency and fat-soluble vitamin (including vitamin K) malab-
sources obtained from the foods’ ingredient lists could provide sorption. Inadequate intake of vitamin K may be a component
imprecise guidelines. Commercial and homemade foods can be of overall vitamin K deficiency, particularly if the patient has
supplemented with psyllium husk fiber (1 tsp/5 to 10 kg body experienced prolonged anorexia (cats with hepatic lipidosis).
weight, added to each meal). If loose stools occur, reduce the Coagulation abnormalities are common in dogs and cats
supplemental fiber by half. with hepatobiliary disease. In dogs with naturally occurring
liver disease, 50 and 75% had an abnormal prothrombin time
Branched-Chain Amino Acids (PT) and activated partial thromboplastin time (APTT), re-
The abnormal plasma amino acid profile in patients with spectively. More than 90% of dogs had at least one abnormali-
hepatic disease can be improved by feeding a protein with an ty (Center, 1996; Webster, 2005). At least one coagulation
amino acid composition high in BCAA and low in AAA, or by abnormality was present in 82% of cats with liver disease.
an intravenous amino acid infusion with a similar profile. How- Prolonged PT was noted in 73% of cats and factor VII activity
ever, a causal relationship between a deranged BCAA:AAA was below reference range (<60%) in 68% of cats. When clas-
ratio in plasma and cerebrospinal fluid and HE has yet to be sified according to underlying pathogenesis, vitamin K defi-
elucidated. Plasma ammonia levels decrease in dogs with HE ciency was the most common abnormality found (11/22).
after administration of BCAA-enriched intravenous infusions Other abnormalities were less common and included hepatic