Dog eating too fast

New post for clarification: My 5 year old pit bull eats his food way too fast. He already has a slow feeder, and even only putting a little in it at a time he still tries to suck it down too fast and chokes cause he doesn't chew it at all. Besides having to feed him a single piece of food at a time (which he still will not chew), how can we help him so he's not hurting himself from eating. He is on a regular feeding schedule and eats the vets recommended daily amount, has been for years.