I am not an expert, but I would recommend rinsing the conditioner. You can leave a little, but I believe not rinsing at all would make the matting problem worse and give your baby the itchies.
I think keeping your pup clean and brushed is the best way to combat mats and tangles. You can also try a brushing/leave-in conditioner or similar product. Finding the right one for your pup's hair can be a challenge. What works for one coat, may not work for another.
Many people like Chris Christensen's Ice on Ice Spray. Some people use a dab of PetSilk Silk Serum. I like Vellus Anti-Stat spray. There are rave reviews here about Iv San Bernard for cotton coats. The list is long.
