Demi Lovato -- Dog Mauled to Death by Coyote

Demi Lovato's dog Buddy was ripped apart by a coyote ... and she's the one who made the gruesome discovery.

TMZ has learned Demi's dog was torn to shreds Sunday ... after a coyote wandered onto the backyard of her LA home.

Demi was devastated saying, "We are absolutely heartbroken to be writing this but Wilmer and I are devastated to inform you that we lost our little angel Buddy last Sunday. He was taken from us way too soon in a tragic accident."

The pop singer was so stricken with grief she cancelled her "Good Morning America" appearance scheduled for Thursday.

RIP Buddy.