Debby....I don't know if this will help....but when my sister and I were teens, "her" cat was a sweet tabby named Squeak.

Squeak did get hit by a car....but managed to reach the yard...there were no apparent signs of damage, but the internal injuries were what did the damage.

The same thing happened to my neighbour last year(she will NOT make her cats indoor kitties! grrr. And don't take that wrong - I KNOW you had taken great care to cat-proof your yard and kept an eye on your babies...like kids, just two seconds, and they can wander off. My neighbour just lets hers wander all day anywhere...)

Maybe that happened to poor Payton.

hugs hugs hugs to you!

Catty1