that's the way smart folks do it . kinda hard to keep line breeding dogs when your foundation dogs don't make it out the woods one day , ain't no differant than breeding roosters you get some good foundation stock and test the offspring . the brood fowl or brood dogs are tested by the quality of the offspring . you can cull anytime .
No disrespect intended to you, but if a cur dog dies at 10months-2 yrs old on a hog in the woods, then that dog has "proven" to be a bit more careless than I'd want as my "foundation". Now, accidents do happen of course but I'd say on the whole that natural selection is helping to ensure that a carelessly gritty dog isn't spreading his careless genes around. I would hate to spend year after year after year having to always run a pack of pups because I was too proud to recognize that all of the dogs I'd been producing have a tendency to get killed by their second year of hunting.