[stars & stripes forever]

Perhaps the family that had the dog could not afford to feed him because of the rising prices.

[Salamander]

Someone took her, kept her, didn’t bother to return her to her chip-registered rightful owners and then threw her away when she became old and sick.
Thank God her real owners have her now and can care for her.
Bet on it.
Hope karma is watching.

[PghBaldy]

The most likely answer is the family entered a time portal for what seemed like a few minutes, but back in this Universe, twelves years had passed on Earth.