If your dog has Cushings, there are several sources for dietary information on the Internet recommending that you abandon commercial dog food in favor of home prepared meals. I'm writing this because I want other pet owners to know that while this can work very well for your pet, under certain circumstances you need to stick to commercial pet food.
At the time we discovered that our dog Muttley has Cushings, we switched her over to home-prepared pet food. I tried to follow the advice from VetInfo.com in particular, since they seem to be the only authoritative source that also manages to explain the bias of their information:
"The only dietary recommendations I can find are in Small Animal Clinical Nutrition III by Morris, et. al. It says to feed a high protein, low fiber, low fat, low purine diet. It suggests that it is important not to oversupplement calcium. It is also important to make sure potassium levels are adequate and that sodium is not restricted in any way if mitotane (o'p'DDD) is being used to treat the hyperadrenocorticism. Also, it is important not to restrict water intake, as you might imagine. Feeding Hill's i/d diet is one way to meet the requirements for these things. One of the book's authors is the son of the veterinarian who founded Hill's, so there may be a little bias in the recommendations, at least as to the recommended diet."
As per their advice, I stuck as strictly as possible to low-purine, high-protein foods when preparing her meals, and the results were fairly immediate and impressive. Muttley was more alert, and more importantly her thirst and subsequent urination problems were reduced to a manageable level. Since we were in the process of waiting for a complete diagnosis (adrenal vs. pituitary Cushings) and then for a prescription for trilostane which is only available in our area through the mail, we were lucky that the home-made food worked so well. In the meantime, needless to say, she loved that food, and so did our other dogs.
However, Muttley, like many Cushings sufferers, is an older dog, and her health is delicate. We've found out through trial and error that the home-made food causes harmful side effects. She's had several bouts with both diarrhea and constipation, which can be very problematic for any senior animal, but which proved especially difficult for her, given her mobility problems. I'm sure there must be some way to give her exactly the amount of fiber she needs naturally. However, I didn't realize that by attempting to adjust the amount to suit her - and I tried a couple of times to get it right - I was essentially treating her as a lab experiment, and she's in no shape for that.
The solution was to put her back on straight kibble, to which I add some chicken stock (either strained home-made chicken stock or low-fat, low-sodium canned chicken stock) for flavor. We did, however, switch from the less costly Purina One to Natural Choice, Large Breed Adult, from Nutro. It seems to be worth the high price, because it returned Muttley to normal in about one day. And we know it's the Natural Choice that made the difference because of my failed attempts to make the home-made food work for her; each time, the return to kibble fixed the problem.
In general, home-prepared dog food is probably more nutritious, and if you've got the time to prepare it and a dog who responds well to it, I would recommend it over manufactured dog food any day. But if your dog is older, in fragile health, or under treatment for Cushings, and you find that home-prepared foods are causing her digestive or intestinal problems, you should feed her instead the best manufactured kibble you can find. Remember that dog food manufacturers do have the scientific knowledge to supply all your dogs minimal nutritional requirements and provide them with the correct level of fiber, and that can make all the difference.