Workup for dogs or cats with chronic liver disease is often recommended when liver enzymes are elevated on a bloodwork screening profile (ALT, ALP, total bilirubin, GGT). Unfortunately, these changes are not specific for one particular liver condition and additional testing is often required to narrow the possible differential diagnoses. The next level of testing may include imaging (abdominal ultrasound, radiographs), bile acid testing (pre and post-prandial), testing for hyperadrenocorticism (Cushing’s disease), blood ammonia levels, and tissue sampling (liver aspirates or biopsy with copper evaluation). The most common diagnosis on histopathology examination is chronic hepatitis which is characterized by variable types of inflammation mixed with signs of regeneration and/or fibrosis. The inciting cause of this chronic inflammatory condition may never be determined but various infectious agents, genetic conditions (copper storage diseases), drugs, or toxins may be considered.
The liver is responsible for numerous important metabolic functions involving proteins, carbohydrates, lipids, blood coagulation factors, vitamin storage, bile production and drug metabolism. There are usually no or minimal clinical signs until disease progression is quite advanced and symptoms may reflect the extent of liver damage. Signs of severe liver dysfunction may include fluid accumulation (abdomen), yellow discoloration of skin/eyes/mucous membranes (jaundice/icterus), decreased protein status (albumin, total protein), low blood sugar, bleeding tendencies, and signs of hepatic encephalopathy (HE) (confusion, lethargy, hypersalivation, wandering, ataxia, stumbling, star-gazing, seizures).
Key points for nutritional management of liver disease include feeding adequate (or appropriate) calories to maintain energy balance (unless weight loss is needed) and providing adequate high quality protein. Restriction of protein is not needed unless signs of HE are present. If HE is present, reduction of protein intake is indicated relative to the prior diet and preferred sources may be vegetable and dairy instead of meat-based proteins. Highly digestible carbohydrates should be present to provide a ready source of glucose along with a mixture of fibers to promote optimal gastrointestinal bacterial balance, normalize stool character and/or prevent constipation. Fat in the diet may be used for palatability and to increase energy density if weight gain is needed as long as bile production is adequate and fats are well tolerated. Water soluble vitamins may be deficient if appetite and intake is poor. Fat soluble vitamins may be compromised as well also due to poor intake or disruption of metabolism from abnormal bile flow. Abnormal copper accumulation can only be determined with a liver biopsy and quantification. If levels are elevated, medication and a low copper diet is used to decrease hepatic copper levels. Zinc supplementation may also be used after treatment. Antioxidants may also be used as supplements on top of a balanced diet (vitamin E, SAMe/milk thistle).
A key point is that diets for dog’s with liver disorders needs to be tailored to each individual patient as no set recommendations are available for all liver disorders. Diets also will need adjustments based on how they respond and/or for any concurrent medical conditions. Over time, if the liver disease progresses, continued adjustment of the nutrient profile may also be required. It is important to check in with your primary care veterinarian and your veterinary nutritionist to ensure you have the best diet for your pet.
Laura Gaylord, DVM, DACVIM (Nutrition)