Our Daisy had parvo as a puppy. not as young as your Serenity though. It itook three days but after plasma and blood she came through it. My prayers and thoughts are w/ you . There is alot more they know about parvo in the 14 years since Daisy had it.
Miss Chevy Cruz - 1/25/2013-1/29/15
Thunder -1/25/13 -7/25/15
Lucky-GSD -Rescue -2/16/03 - 03-21-16
Charlie- GSD-Rescue - 7-4-12