Many members on the forum use a hair dryer, it has to be held far away from the pig, so they get minimum heat on their fur, and has to be set on the lowest setting. No harm will come to the piggy if you hold the hair dryer far away. Some piggies cannot have a hair dryer on them as they get distressed and scared.its not a good idea, you cant see when a guinea pig is getting burnt by it, they burn so easily too
If he was soaked he could have a urine infection. Maybe he needs a check up?