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I would go all concrete as it is the easiest to clean. Put a house or something in their for the pup to lay in/on and if you can, cover the area for shade as well as protection from the weather. One nice thing about concrete over the whole thing is you don't have to worry about the little rascals digging out.
so if you hunt chukar, hills, rough shale, I have been told that you can condition pads in the kennel by either gravel or "rough" concrete floor. I am shifting to a new pad, rough concrete for this reason...
My kennel for my lab is 12 X13, 1/2 covered by my carport roof. I have a igloo dog house. and the floor is pea gravel. Cheap and clean. just rake it once in awhile. Any bad stuff not picked up just filters away.I clean up droppings every day.I bed her house with straw so she can nest.