MIL feeds her dog dog food plus human food - dog gets 2 meals of dog meat and kibble a day plus 2 or 3 meals of human food, not just leftovers, she cooks extra so the dog can have
If MIL goes out for a meal to a restaurant, she takes a bag with her and empties leftovers into it.
If she goes to a party with buffet food, she nicks a load of food for the dog (she once brought home 17 chicken drumsticks)
AIBU to think this is unacceptable and to be embarrassed by it