If the pet is sick or old, try to talk with your kids about the possibility of his death.

-Let him/her express his/her emotions and tell them its okay to feel sad.

-Never tell him/her that the pet ran away, you will be giving your child a false hope that he might return.

-No need to tell your child details about how the pet dies, give limited answer.

-You can welcome another animal to your house when the pain starts to go away.