What do you mean you've never kept a dog for longer then 4 years? I think your mom needs to learn dogs are NOT toys and you can't just throw them away when they can't do their "job" anymore. Why don't you talk to her about breeding dogs? Explain about puppymills and BYB's, and that she is probably a BYB....
Who knows...maybe it's best if Trigger gets a new home. With all the love he deserves.

IMO.