Sally, I really think the trouble I'm having is because I only had access to Nature's Variety frozen stuff for so long. It was great for the initial transition when they had the rabbit. But note the second ingredient on NV Rabbit is pork fat.

My cats didn't love rabbit meat. They loved rabbit meat with pork fat.

So when I had no choice but to use pretty much only NV lamb or chicken, they got sick of it and bored. So I went to the supermarket, and bought fresh lamb from NZ, and organic pasture-fed chicken and turkey. They LOVE fresh meat. I realize it's not balanced nutritionally, and I have been giving a meal of just fresh meat at least every-other day here for a couple of weeks now... but for my guys, the problem isn't that they don't like meat. They don't like Nature's Variety - or the other rather dry, frozen commercial patties (Stella & Chewy's, Primal).
And yes, we're having issues - though not all our cats are. I think it's something people should expect when transitioning.

If there are no problems - GREAT! But think of it like this:
All your life, you've been eating cereal whenever you want throughout the day. It's got vitamins added, meets all your nutritional needs. You also eat canned stew, though you switch between beef and chicken stew.
Your next shopping trip, instead of getting cereal and canned stew, you go to the health food store. You buy organic fruits and vegetables and whole wheat pasta, and that's what you start eating.
Being a person, you force yourself, even though the pasta tastes like cardboard to you, you know it's good for you. Your mouth and teeth hurt from chewing on carrots and biting apples. Your body is in shock from this sudden switch.
That's not to say it wasn't the right thing to do. But you may have problems with diarrhea or constipation or feeling nauseous and throwing up as your body adjusts to the new diet.
On the other hand... you sleep better, you have more energy. So you know it's worth the problems of the transition.
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I don't know anything about CRF and raw feeding, but found this:
http://www.shirleys-wellness-cafe.com/renalfailure.htm I don't know how closely you work with your vet, but I would definitely find out if your vet is open to the idea of raw feeding.
In the meantime, I think the first step is moving to timed meals. I think you should get your kitties on probiotics now, while you decide how to proceed.

Does your vet already have Sven on digestive enzymes? If not, why not? would be a good question for the vet.

In everything I've just seen regarding CRF, it seems digestive enzymes are an important tool. These may also ease some of the transition problems.
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I transitioned mine from free feeding kibble to canned food, timed meals in November 2010. It was NOT fun. My biggest hurdle was getting Flowerbelle, Lazlo, and Tuxedo to eat enough food at each meal. I had to settle on four meals a day to get them to eat enough. And they still didn't, so even though I did not free feed kibble, I definitely continued to feed kibble to just them. I didn't become a kibble-free home until ... a few days? a week? into the raw transition. I replaced the snacks of kibble they were getting with Whole Life chicken.

Flowerbelle hates it, so for a while there I'd give her some canned food as a treat.
But the switch to timed meals is the first hurdle. You'll probably have to do four (do you work? If so, you may have no choice but to make it three!) ... that said, the problem I'm having now with Tuxedo, I'm pretty sure, is because I'm moving from four meals a day to three. On raw food, the cats produce more stomach acid. This makes them nauseous if they don't eat when they're used to eating. So if you CAN move them to three meals a day, that is the better option, because it doesn't tie up so much of your time - and it MAY be easier in the long run to get them eating their kibble at the times you would want them eating canned or raw.

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Issues with transition:
Some cats will love meat right away: Lauren's Wendall and Walden; my Billy, Ming Loy, Chumley, and Sheldon - though he hates NV, he loves meat - Flowerbelle, and Spooky. (Yes, Spooky's having an issue, but it's not because she doesn't like raw food). Flowerbelle's issue isn't that she doesn't like meat. Her issue is that she would rather eat 3 or 4 bites of food at a time, about a 100 times a day.

I have to use the "enticements" to get her to eat - not because she doesn't like the food, but because I need her to eat enough at each meal.
Some cats will not even recognize raw as food: Carolina's Lucky.
Some need convincing: Bugsy, Hope, Lauren's 4Ps, and my Lazlo and Tuxedo.
Flowerbelle and Spooky do NOT like Halo or Whole Life (like Halo, but cheaper) chicken. Dehydrated, rehydrated, doesn't matter. So you need other tools in the arsenal, for increasing "palatability." (Meaning stuff to help you get them to both recognize it as food, and to encourage them to finish their meals). In my arsenal: Whole Life chicken, Whole Life lamb, Fortiflora, dried chicken livers, and dried beef liver. These are all used sparingly - light sprinkles or coating on top. Helps to get them going, and helps them to keep going. I do NOT use Fortiflora as a probiotic (which is what it is). I use it to make the food smell enticing.
Other things to consider:
Bone-in meals vs. calcium supplemented meals. If your cats are used to eating kibble, based on what Carolina is going through with Lucky right now, I would REALLY recommend starting with commercial raw that is NOT bone-in. Nature's Menu is relatively affordable even with shipping, and it has calcium supplemented rather than being bone-in.

Rad Cat seems to be a GREAT transition food (also supplemented and not bone-in), but it is expensive, even if you can find someone that supplies it where you live. Look into it and see. But it seems that starting with Rad Cat or Nature's Menu might be a good plan.

And yes, Lucky went straight from kibble to raw.

I wouldn't bother with introducing them to canned - unless you've just never offered it to them. If they like it, it can be a valuable tool in the transition.
What I would do if I were in your place, I think, is first I'd talk to the vet about Sven and raw. I'd talk to the vet about getting him on digestive enzymes, and I would definitely get them all on probiotics.
And the next time you're making chicken or pork chops for dinner, as GoingPostal suggests, slice off a very small piece for each kitty and offer it to them as a treat. See what happens!
But focus on one thing at a time... and the first thing to worry about is getting them on timed meals, IMO. And you don't need to buy expensive raw food to see if they like it. Start with little snips of whatever you're having before you cook it.

(Although a lot of cats DO seem to have a problem with beef). Just don't offer them already-ground stuff from the supermarket. And personally, I had my cats on probiotics for about two weeks before I fed them any raw, just to make sure their gut flora was in good shape.
If they don't like it... then don't invest in commercial raw yet. Just keep putting that little snippet of chicken or whatever on their plate when you feed them kibble.
