Treatment of liver disease: Medical and nutritional aspects (Sponsored by Nestle Purina)
Few controlled studies have investigated treatments for liver disease in dogs and cats. My basic treatment goals for patients with this disease are
The liver is paramount in an animal's metabolism, playing a key role in regulating protein, carbohydrates, fat, vitamins, and minerals. Metabolic derangements that occur with liver disease can lead to malnutrition, impaired hepatic regeneration, and the clinical consequences of hepatic insufficiency.Basic nutritional concepts
Anorexia and weight loss occur commonly in patients with liver disease. Therefore, one of the most important aspects in liver disease therapy is ensuring that the patient has appropriate energy intake to minimize catabolism.1 When treating liver disease, there is a common misconception regarding the fat content in the diet. This is especially true of nutritional management of feline hepatic lipidosis, as some believe that affected patients should be fed lower-fat diets. Fat not only improves palatability but also provides important energy density to the diet. In general, lipid restriction is unnecessary in patients with liver disease.
Carbohydrates should make up no more than 35% and 45% of the diet's total calories in cats and dogs, respectively.1,2 Adequate carbohydrate intake is important to maintain glucose concentrations. Additionally, feeding small yet frequent meals throughout the day may help maintain glucose concentrations.
A misconception also exists regarding the optimal dietary protein content in animals with liver disease. It was previously thought that patients with liver disease should be placed on a protein-restricted diet to reduce the liver's workload and the production of detrimental nitrogenous waste products. This assumption, however, is not well substantiated. Many veterinary nutritionists and gastroenterologists now believe restricting protein could be detrimental, especially in patients with a negative nitrogen balance.1,3 The goal of dietary protein intake is to adjust the quantities and types of nutrients to meet the patient's nutrient requirements and to avoid the production of excess nitrogen byproducts, which cause hepatic encephalopathy.
It is always important to provide the patient with a high-quality, highly digestible protein source.1 Poor-quality proteins may aggravate hepatic encephalopathy and fail to promote hepatic regeneration. In some instances, the protein requirements for patients with liver disease may actually be greater than those for healthy animals. Most high-quality commercial or prescription diets are suitable for this purpose. As a general recommendation, dietary protein should represent 15% to 20% of the digestible kilocalories (kcal) of the diet.1 In general, most highly digestible diets, such as gastrointestinal diets, would be adequate for most liver conditions. Clinically, protein restriction should be instituted only in patients with evidence of protein intolerance; most often these are patients with portosystemic shunts or signs of hepatic encephalopathy.4 Because cats have such a high protein requirement, I rarely—if ever—limit protein intake in cases of feline liver disease, such as lipidosis, and I find hepatic encephalopathy is an uncommon consequence in cats.