If I'm just going to run to the vet or to a close lake where I go out trail riding, then no, I don't use any bedding, they can pee outside. On trips longer that 1 hr, like from my house to a horse show in Tulsa or OKC, I'll toss down about 1/2 bag of bedding just in case they need to pee. On LONG trips, like from here to Sport Horse Nationals in KY, I bed DEEP. I have an oversized 3 horse slant load trailer and I'll use 5 bags of shavings in it for a long trip to keep things soft of their legs and to absorb any and all pee or spilled water. Once I get to my destination, I clean out the solid waste and wet spots just like cleaning a stall. Once back home, I clean it all out and then pull the mats and wash the trailer down really well.