Hi just wondering if this has happened to any one else with cats? Both female and spayed, had since kittens over year and a half old. Both are indoor and outdoor cats but they prefer indoors! One went missing Thursday 12th April and the other on sat 21st just gone. Is this common for both cats to leave or should I be fearing the worst? Thanks

Have you checked around with your neighbors?
Sometimes cats will take off and stay gone for a couple of days the only way to prevent it is to keep them indoors.
Depending on what type of area you live in, any number of things could have happened,
Taken in by another family, roaming around scavenging, victim of neighborhood dogs, lots of possibilities.
I do you you find them and they are safe and healthy.