I believe we live forever...and once we are reborn as a human we NEVER revert back to being an animal....if you can get a copy of "Gnani Yoga" by Yogi Ramacharaka (long out of print) he explains everything.

"First the mineral (remember crystals are living beings)...then the plant....then the animal" (please remember insects and the hated spiders are God's children too)...."then the human".

This is what Ramacharaka called "the evolution of souls"...how a soul starts as a little spark of the divine life as a mineral,then a plant....after several lifetimes becoming an animal...the domestic animals (dogs,cats etc) are living several lives with humans to get their final (although they don't realise it) instruction in being human.

When a soul becomes human....your troubles start..."Being cast out of the Garden of Eden" would be a good description...animals live for the NOW...no regrets over yesterday,and no worries about tomorrow (aren't they lucky?)

But we "superior" humans are different....we have a subconcious mind and a concious one...the subconcious gives ideas to the concious .....(like Eve giving Adam an apple)....and the human is driven out of Eden.

We are now capable of deceit,and plotting....and worrying about tomorrow !!....instead of trusting God like animals and birds do.

Blessings.....Mike