Page 618 - Small Animal Internal Medicine, 6th Edition

590 PART IV Hepatobiliary and Exocrine Pancreatic Disorders

Treatment of Underlying Cause reserved for patients with an identified underlying cause.
If an infectious cause is identified, this should be treated Without a biopsy, nonspecific treatment should consist of
VetBooks.ir appropriately. Any significant copper buildup should be che- choleretics, antioxidants, and diet. The use of glucocorticoids
and copper chelators must be reserved for biopsy-confirmed
lated (see later) and managed with a low copper diet. Any
suspected hepatotoxic drug or nutraceutical should be
Choleretics
removed and replaced as necessary with a safe alternative. cases only.
This can be particularly difficult in the case of a dog with Ursodiol is widely and commonly used in dogs with
chronic hepatitis and concurrent life-limiting degenerative chronic hepatitis. It is a synthetic hydrophilic bile acid that
joint disease where the continued use of nonsteroidal anti- is choleretic and modulates the bile acid pool in biliary stasis,
inflammatory drugs (NSAIDs) is contraindicated. making the bile less toxic to hepatocytes. It also has antiin-
flammatory and antioxidant properties, and studies suggest
Diet that it is synergistic with SAM-e and vitamin E. The only
Dietary management is always an important part of treat- absolute contraindication is complete biliary obstruction,
ment for patients with liver disease because the liver is the which is very rare in dogs and would usually result in obvious
first stop for nutrients on their way from the gut to the sys- acholic feces. It can be used in any dog with chronic hepati-
temic circulation, and it is intimately involved in the metabo- tis, particularly in those associated with biliary stasis, and
lism of nutrients. This metabolism is compromised in can safely be used without a biopsy. However, as with other
patients with liver disease; in addition, dogs with chronic drugs used for the treatment of canine liver disease, there is
hepatitis typically have protein-calorie malnutrition, so limited, although encouraging, evidence about its efficacy. It
excessive restriction of nutrients can be harmful. may be more helpful in some diseases than others, but this
The nutritional requirements for dogs with liver disease has not yet been determined for dogs. The recommended
are outlined in Table 36.2. The most important consideration dose is 10 to 15 mg/kg orally (PO) q12h (or divided into two
is dietary protein concentration. It is now recognized in doses given q12h).
humans and dogs with liver disease that, to avoid a negative Antioxidants
nitrogen balance, dietary protein should not be restricted. A variety of antioxidants are used in dogs with chronic
However, it is important to feed a high-quality, highly digest- hepatitis. The best documented are vitamin E and SAM-e.
ible protein to reduce hepatic work and decrease the amount Vitamin E appears to be beneficial at a dosage of 400 IU/
of undigested protein that reaches the colon, where it is day PO for a 30-kg dog, given as a water-soluble preparation
converted to ammonia. Most ammonia reaching the sys- once a day. Dosages for smaller dogs are scaled appropriately.
temic circulation in the portal blood of animals with con- SAM-e is a glutathione precursor and is of particular benefit
genital and acquired PSSs originates not from dietary protein for dogs with toxic hepatopathy (see earlier) and those with
but from enterocyte catabolism of glutamine as their main biliary stasis because bile is a potent oxidant. It is synergis-
source of energy. This cannot be avoided without starving tic with vitamin E and ursodiol, and an argument could be
the enterocytes, so other means of controlling HE are recom- made for it being beneficial in any dog with chronic hepa-
mended in addition to dietary restriction (see later). Most titis. The recommended dose is 20 mg/kg PO q24h. There
prescription diets available for dogs with liver disease (Hill’s are some studies documenting its use in dogs, but more
l/d diet, Hill’s Pet Nutrition, Topeka, KS; Royal Canin Hepatic research is needed to define in which diseases it is most
Formula, Royal Canin USA, St Charles, MO) are ideally useful. SAM-e is a very unstable molecule because it is a
formulated, except that they have lower protein than is ideal methyl donor and must therefore be carefully packaged and
for a dog with chronic hepatitis. Therefore these diets should given on an empty stomach. The pharmacokinetics and GI
be fed as a baseline in small amounts and often with the availability in dogs have been published for the pure prepa-
addition of high-quality protein to the food. Dairy and veg- ration (Denosyl, Nutramax Laboratories, Edgewood, MD;
etable protein produce the best results in humans and dogs Center et al., 2005). However, SAM-e is increasingly being
with liver disease; cottage cheese is a good choice to add to marketed as a polypharmacy nutraceutical in preparations
the diet. The amount to add to the food is difficult to esti- with other nutraceuticals and vitamins combined. Pharma-
mate. It is advisable to start with 1 or 2 tablespoons of cottage cokinetic and absorption data should be sought from the
cheese per meal, monitor clinical signs and blood protein manufacturers of these products to ensure that the SAM-e
levels, and for gastrointestinal disease such as Hill’s ID diet is absorbed in effective amounts.
or Royal Canin gastrointestinal or a clinical diet formulated Another antioxidant commonly used in dogs with
adjust accordingly. Alternatively, a clinical diet formulated chronic hepatitis is milk thistle (Silybum marianum). The
for liver disease with a less restricted protein content can be active ingredients are flavonoids, commonly referred to as
used, such as Purina HP. silymarin; the most effective of these is believed to be silybin.
There are few studies on the use of flavonoids in dogs, and
Drugs the only clinical studies are in regard to acute toxic hepati-
Drug support in dogs with idiopathic chronic hepatitis is tis. Silybin may have the potential to be a helpful adjunct
nonspecific, and attempts to slow the progression of disease to therapy in some cases, but much more information on
and control clinical signs. Specific drug treatments are absorption, availability, and ideal dosage is necessary. Silybin