Some people, yours truly included, do not have children and their pets serve as surrogate children. So there's that attachment.
I also cannot conceive of a God (that I'd care to worship) that would create a heaven yet leave out our faithful animal companions. Something like that wouldn't be heaven at all; it would be very much the other thing.
As much as I hope and feel that all beloved pets will be with their people in Heaven, to put them above God is blasphemy. It is God who makes Heaven what it is, not the presence of any other souls and certainly not the presence of pets.
Because of His perfect love, we will be unable to feel sorrow for those we will never see again, people or pets. Even if God does not allow earthly pets into Heaven, I take comfort in believing that they would simply rest in peace.
Still, I'm hoping.
Put another way, the very fact of being alive means there is a soul (even in plants and amoebas) and that soul is connected to a realm as real as dimension time yet not at the mercy of temporal shift. The fact that ALL humans will be resurrected --some to life everlasting in God's presence, some not in God's presence-- is an indication that All life will be resurrected and the innocent will remain in God's presence. ALL animals are innocent of spiritual rebellion (because they lack a spirit though they are souls with bodies) thus they are suffering now only because of Adam's fall and the resurrection of Christ has dissolved that curse for them.