my westie does the same thing, we have to keep the area clipped. they also sell "baby wipes" for dogs, you can get them at pet smart. or if you're so inclined wipe his bum with a wet papertowel afterwards. my daughter is 12yrs old, i thought i was sooo done with bum wiping; until i got my puppy! his was so bad one time, it was like a toddler getting chewing gum stuck in their hair, i almost had to take him to the vet to have it removed, it actually fused to the hair all the way around his anus and he couldnt potty. that was absolutely awful. but me and my daughter finally got it.