Hello, sorry I got on here so late, but I see you have had quite a bit of advice. Three of my dogs eat Taste of the Wild-Pacific Salmon. So far, they have been doing well on it. I haven't had experience with liver problems in dogs-so I don't know what the diet should be. I do know that prednisone can have side effects-so if it is possible, it would be best if she could get off it. Zoey is a beautiful gal, and you must have been so worried about her.
If your dog is showing symptoms of liver disease, it may make sense to make some dietary adjustments. It is better to feed several small meals a day rather than one or even two, if possible. I would recommend feeding moderate amounts of both high quality protein and fat. Dairy products, including cottage cheese, ricotta cheese and yogurt, may be easier to digest and produce less ammonia than meat products -- you may want to look for low salt varieties if you feed a lot of cottage cheese, or if your dog develops ascites (fluid retention). Eggs are an excellent protein source for dogs with liver disease. White fish can also be used.

Liver disease is one condition where it makes sense to add grains, as soluble fiber helps remove ammonia from the system so the liver does not have to process it. Oatmeal is particularly high in soluble fiber and would be good to use, as long as your dog doesn't have any problems with it (use whole rolled or quick oats (cooked), which have more soluble fiber than instant). Boiled white rice and, to a lesser degree, pasta are useful due to their high digestibility. I prefer feeding at least half meat and other animal products, and no more than half grains and other carbohydrates, unless less protein is needed to control symptoms of hepatic encephalopathy. For those who use a spreadsheet, you should feed a minimum of 1 gram of protein per pound of body weight daily (as determined by a nutritional analysis, not grams of meat), and carbohydrates should not provide more than 45% of calories.
Avoid supplements with copper and [replacer_a], including most organ meats, especially beef liver (but not chicken or turkey liver, which have little copper) -- see foods that are high in copper for more information; also see the Vitamin & Mineral Content of Various Organ Meats but be aware that you can't compare these foods directly as they use different measurement sizes for different foods. Copper can accumulate in the liver when bile excretion is reduced and cause further damage. Lamb, pork, duck and salmon are high in copper; turkey, chicken, and other fish have moderate amounts of copper; and beef, cheese and eggs are low in copper. In advanced stages of liver disease, both copper and sodium (salt) must be severely restricted; salt is restricted to help prevent ascites (fluid build-up in the abdomen) related to low albumin levels, which are caused by poor liver function. You can use the Copper Nutrient List to check for amounts of these nutrients in specific foods. You can also give a zinc supplement to help bind copper, especially if you suspect copper accumulation. See this article on USDA Nutrient Database for more information. Also see [replacer_a] for an overview. I found a list of [replacer_a] showing copper content of various commercial foods, but I would verify the amount of copper in the food with the manufacturer before using any of them, as things may have changed since that list was created.
The amino acid [replacer_a] can help with fat metabolism and thereby be beneficial for liver disease, and [replacer_a] may be helpful in reducing ammonia that can accumulate with liver disease. Dogs with problems absorbing fat may benefit from a low fat diet using medium-chain triglycerides (MCTs), a form of fat found in dairy products and coconut oil. Use virgin (unrefined) coconut oil sold in glass jars and give up to 1 tsp per 10 lbs of body weight (start with less and increase gradually).
Good supplements to give would also include Vitamin B complex and vitamin E. Zinc should be increased above normal levels to help bind copper, and because its antioxidant properties help to protect the liver. Vitamin A should be limited with liver disease -- normal amounts are fine, but don't give higher amounts. Cod liver oil, which is high in vitamin A, should be used sparingly, if at all, and liver should also be limited (liver is also high in copper). Vitamin C should not be given to dogs with copper retention, but otherwise is beneficial. Fish oil (body oil, not liver oil) can be given in moderate amounts, maybe 1000 mg per 20-30 lbs of body weight, it's not known whether it's helpful for liver disease or not but can help with inflammation.
Dr. Jean Dodds recommends her [replacer_a] for dogs with liver disease, but it is very important to understand that this type of diet is only needed for dogs with very severe liver disease that is causing hepatic encephalopathy (neurological problems caused by too much ammonia in the system). It is definitely not indicated simply because your dog has elevated liver enzymes, which may not even indicate liver disease (see above). Although I feel it is unnecessary, I see no problem using this diet short-term (two or three months) for dogs that may have liver disease, if it makes you feel better and your dog does not object, but I do not recommend feeding such a restricted diet with so little variety long-term unless absolutely necessary. If your dog is suffering from hepatic encephalopathy and needs a severely restricted diet for this reason, this diet would be appropriate, though more variety would still be preferable. See [replacer_a] for a more complicated, but more complete, version of the same diet. It's fine to use the simple version in the short term, but if you need to feed a restricted diet for more than two or three months, you should use the more complete version. Again, you should also use variety rather than always feeding the same exact foods (for example, Dr. Dodds mentions substituting chicken for fish, and adding eggs to the diet).
See [replacer_a] for information on a cooked diet and treatment protocol that one person used successfully to treat their Cairn Terrier with terminal cirrhosis of the liver. Othershave also reported success using this diet, and it is not as low in protein as the Dodds diet above, so it would be a better choice for most dogs. Note this recipe doesn't include calcium. Add calcium at the rate of around 800 mg per pound of food. You can use eggshells that have been ground to powder in a clean coffee grinder, where 1/2 teaspoon ground eggshell provides about 1,000 mg calcium.You may also want to substitute eggs and dairy for some of the turkey.
[replacer_a] has additional information on this subject, and I have also seen Donald Strombeck's book, [replacer_a] recommended for liver disease recipes (these are cooked diets without bone). All of these are low in protein and so would not be appropriate except for dogs with advanced liver disease. You can see his recipes on his website: [replacer_a].
As always, I recommend that a variety of different Copper Toxicity/Chronic Active Hepatitis be fed, rather than just a single, unvarying Diets for Dogs with Copper Associated Liver Disease like The Best Foods For Dogs With Chronic Active Hepatitis.
There is a possibility that certain fruits are liver protective, including watermelon, grapefruit, lychee, fig, kiwi, cherry, Japanese plum, and papaya.