You get a lepto jab in with the parvo jabs you get when they are pups, BUT....they only cover several strains of it, not all of them.
I have always taken pups along to ratting when i could, you will probably find it will be a bit overcome by the whole thing and watch, perhaps joining in a bit at the end? Mine were more bothered about playing than working, but that is ok also, they are still getting used to being out with a pack of dogs who are in kill mode with no aggression displayed towards other dogs, a good way of socialising them.
Get some hibiscrub, and give any bites a good wash with