I own and rescue purebred AUSTRALIAN CATTLE DOGS..this is what the breed is and it's recognized in USA, Canada, the UK, and Australia as this breed. Stay away from any other iteration of what someone might want to think is any kind of "Cattle Dog". Or "Blue Heeler" or some dumb "designer dog". Then tell your MIL to get out her search engine and research The Australian Cattle Dog and see what she thinks. Pick up some dog books at the library too.
These dogs are high drive, opinionated and do focus on WORK. If you do not give hem proper and acceptable "work" they will of of course make up their own version which is certainly not going to be something you like. LOL
Any breed has it's bred in personality, and prey drive depending on what it is bred for. Any breed should go to school and be given plenty to do, both using it's brains and giving it exercise. But this breed needs it more than most.
Being as how these dogs were bred to "heel" (this means BITE heels)cattle and not take any guff off of mother cows with calves or enraged bulls, They need a strong leader who can stand up to their independence.
Having said that I love ACDs! LOL I like their attitudes as they are known amongst those who are familiar with the breed as VELCRO DOGS, this because they tend to glom onto the person of their choice and stick like glue.
I suggest that your mom look at a certified rescue organization for the breed she wants, there are lots of real purebreds out there that need homes. And she might even be better off with a young adult dog or even an older one who has already been trained instead of the problems and intense training that a puppy would take.
I have EIGHT little nine week old ACD crosses right now and they all will be adopted out once they are altered, microchipped, and given all their vaccines.
I put a lot of time, love and training into my foster dogs and will be real careful who they go to. No young children in the home...fenced yards only etc.
Good luck with your MIL...please ask her to use common sense here and not pay any attention to craigs list! If this was such a great breeding it would already be spoken for!
LQ