Dehydrated raw food as treats is...
If you expected 'good', you might be surprised when I say 'maybe good, maybe bad.' It depends on the number of treats that are given, actually.
Giving a cat a few small pieces of dehydrated chicken (or any other meat) won't cause a problem.
Giving a cat a handful of dehydrated treats and, well, you could have the problem my friend has. She was enthusiastic that her normally picky cat would eat a different treat (other than Whiskas Temptations) that she kept giving her cat the dehydrated turkey last night. This morning, the cat is sitting in the meatloaf position, refuses to eat, and acts as if her tummy hurts.
Most meats are 60-70% water (by weight). Commercially dehydrated meat has most of that water removed, so less than 10% of the normally present water remains. (Some dehydrated treats are less than 5%.) Dehydrated food (which hasn't been ground or pulverized) will re-hydrate readily if given water. When the dehydrated food enters the digestive tract, it will pull water from the digestive tract to re-hydrate and usually expand. If the cat is not fully hydrated or does not drink a lot of water near the time the treats are eaten, the now semi-re-hydrated treats will form a blockage as more water is pulled into it and the body slowly digests them. (Without sufficient water, the digestion of them is also slowed.) Eventually the body will move this mass along.
Notice I did put the caveat of not ground nor pulverized. Dehydrated meats that are dehydrated and then crushed and formed into patties, etc., don't seem to cause this type of problem. The reason I believe is the patty, for example, falls apart and does not form a large lump. Also, most dehydrated food specifically says to re-hydrate it before serving. And it is really amazing how much water one small dehydrated patty can absorb!
The solution to my friend's cat's problem is to give the cat sub-cutaneous fluids so that the cat has extra water to soften the treats and help them move along.
The overall solution is to limit dehydrated treats to 2-3 small pieces and only to give them to non-CRF (or other potentially dehydrated) cats.