On a average how long does a catch dog last?

I got my gyp from a boy for twenty five bucks. He put her in the woods one time and she didn't catch. I went and picked her up and took her hunting the same day and she caught three hogs. The second one she caught weighed 225. I have been catching hogs with her ever since. But i always run a vest and collar on her. if she gets a cut that i cant handle she goes to the vet. I have never spent more than a hundred bucks on a catch dog, every one of them caught and i have never had one killed. But i dont believe in spending no 500 or more dollars for one because like every one says, it only takes that one bad hog.