My parents had a dog who exhibited this type of behovior right after spaying. She was mothering her squeaky toys. Since she was still a pup, we were able to get her over the hump by first admiring her "babes" and cuddling them, and then squeaking them, and then finally throwing them and reminding her that they were really toys and fun to play with. She was back to normal after a few games of catch.
It is our choices that show what we truly are far more than our abilities. ~A. Dumbledore