The empty glass jars you fill at the Peka Glade, do any of them work at all when given to your pets?

Nope, you'll need to fill the Ornate Floral Pitcher at the glade to get a Glade Potion if you want to change your pet.

->

Ah. . .thats what I wanted to know. So if you give them any of the other vases, they're worthless?

any of the other vases filled with peka glade water are just plain food.