Boanerges,
As the owner of an elderly dog, I was so sorry to hear of your loss, and can well imagine how you must be feeling. I thought you might find the following comment by Matthew Henry on Romans 8:21-22, interesting.
"Sin is a burden to the whole creation; the sin of the Jews, in crucifying Christ, set the earth a quaking under them. The idols were a burden to the weary beast, Isa. xlvi. 1. There is a general outcry of the whole creation against the sin of man: the stone crieth out of the wall (Hab. ii. 11), the land cries, Job xxxi. 38. (3.) That the creature, that is now thus burdened, shall, at the time of the restitution of all things, be delivered from this bondage into the glorious liberty of the children of God (v. 21)-- they shall no more be subject to vanity and corruption, and the other fruits of the curse; but, on the contrary, this lower world shall be renewed: when there will be new heavens there will be a new earth (2 Pet. iii. 13; Rev. xxi. 1); and there shall be a glory conferred upon all the creatures, which shall be (in the proportion of their natures) as suitable and as great an advancement as the glory of the children of God shall be to them. The fire at the last day shall be a refining, not a destroying annihilating fire. What becomes of the souls of brutes, that go downwards, none can tell. But it should seem by the scripture that there will be some kind of restoration of them. And if it be objected, What use will they be of to glorified saints? we may suppose them of as much use as they were to Adam in innocency; and if it be only to illustrate the wisdom, power, and goodness of their Creator, that is enough."
Yours in Him,
Brian.