Do you cook in oven before dehydrating venison jerky to kill possible bacteria?
Jerky does not need to be pre-cooked, in fact the process of making jerky probably predates the invention of cooking.

The process of salting and drying (and additionally adding sugar, acid, and/or smoke) inherently kills or inhibits growth of bacteria and mold. As long as your meat is cut thin, evenly salted, and well dried you do not need to pre-cook it.

Since the meat is thin, cooking it beforehand will just result in overcooked, stringy meat. If you are using the oven method or a food dehydrator with a heating element the meat will end up cooked.