Can I return my 4 dead cats and 2 dead birds back to the pet shop?

I bough 2 birds 3 years ago and recently found their corpse behind the stove. My other 4 cats died sometime in the backyard about 1yr ago. I don't really know why or how but their dead now. Didn't really notice they were gone until I got home from my months Christian music tour. Can I return these pets back to the pet store? I still have the receipt and feel I got them defected.