I just have to say it, designer dogs are not mutts. They are specifically bred usually combining 2 pure breeds to create a mutt because PETA and others like them have convinced many that a pure bred dog is a bad thing. I love mutts, I have 2 but I also am aware that when I adopt a mutt I have no idea if the parents were health checked. I have no idea if SAS or PRA or dysplasia is in the ancestry. I have little idea of what sort of coat, long or short, the dog will have, if it will be lab sized or terrier sized.
When I want a new dog for my pack (which will be a pack of 2 humans and 1 dog when my 2 oldies die) I will adopt a mixed breed if I fall in love with one (such as I did with my dingo) or I will go to a reputable breeder, one who breeds specifically for show or work and buy a dog who will be a healthy, stable representative of its breed. It probably won’t cost as much as a designer dog and if I adopt from a breed specific rescue the cost will be even more minimal. The breeder will check my background and have me sign a contract that says if I find myself incapable of keeping the dog, they want it back. No hunting for an adoptive family, no dropping it off at the SPCA, BRING IT BACK TO ME!
Please do not get into this mutt snobbery, it is not always the best way for everyone.