These ones are made with a Water Resistant pul shell with super absorbent terry cloth lining with cotton batting on the inside.

They can take quite a bit of water or pee in them and won't soak through; for full bladder loads will probably need an extra liner added to it

XSmall - $12.00 5lbs & under
Small - $14.00 5lbs to 20lbs (Cat Size) 
Medium - $16.00 20lbs to 60lbs
Large $18.00 - 60lbs to 100lbs
XLarge $20.00 - 100lbs t0 140lbs

Custom Order, measurements are needed 

Belly Bands