Hey KYHunter,
Where are you located? I'm in Bowling Green, Ky. The pad should be larger than the kennel. Is this up against a building?Where do the dogs sleep? Dog house or in the building? Advice: Put the pad against a building where ther dogs will enter to sleep. Inside the building the dog box can be used as a work bench. Your building should be at least 8' wide to accomadate storage for food and other supplies. Your slab should be pitched for easy run off. The ones I prefer have a gutter that goes to a 6" drain that is attatched to a pipe going to a drain well. Dig a 3'x4' hole and fill with rip rap on the bottom, let the drain line enter the pitup top, don't use dense grade . I fyou are on a hill then run the drain under ground to the side of the hill. Call for a concrete truck to save time. Make sure your form boards are secure and that you know how to pour and float concrete, a 6" slump is usually easy, you may need to tell your driver to juice it up if it is too stiff when he gets there. Most concrete pours require a minimum 4 yd pour @ $70 a yard. If you are going to build the whole thing from scratch then pour enough to lay blocks for one side of the building. Pole barn the other three sides. The building can have processed 11's as a floor. Lay 2 courses of block on the slab. Your dogs will enter above these and then common frame that wall. A common mistake is to not have enough pitch in the slab or to have low spots that pond out in the middle of the slab.
If you are just pouring a slab quickcrete has a reference guide for the do-it-yourselfer to estimate bags needed. One thing that is a pain is to have 6" of slab beyond the kennel you have to step up on to enter the kennel. Extend this side 40" and you have a walk way. Let me know where you are. If it's close I'll stop and look at it. Masonry is how I make a living and dogs are one of the things I live for.