Parvo is definatly VERY contagious- I had a fun bout of it while I was doing rescue- after years of never having an outbreak a sick puppy snuck by us and came into the kennel with Parvo, unfortunatly at the same time a sick kitten snuck by us with Calcivirus (similar to distemper, but more vampant and deadly) and I had a parvo/calci outbreak at the same time! We ended up with 32 sick kittens/cats and 8 sick puppies, but with ROUND THE CLOCK constant care we were able to save most of them.. We lost 1 puppy and 18 kittens (Calci is INCREDIBLY fast moving, they would be perfectly fine, then they would sneeze and within a few minutes be dead in some cases) I had SubQ and IV bags everywhere and I made all the volunteers change gloves and scrub covers before moving from each cage, and we scrubbed everything down with bleach on a daily basis. I dotn think I slept at all those two weeks, or if I did it was for like 15 minutes at a time
Afterwards, we treated the yard and kennels- this is absolutely possible, because she can still pick it up in the soil after she has been treated- what we did is I took a couple dozen gallons of bleach, loaded it in a pressure washer and bleached the entire backyard- it killed everything, including my grass- but no more parvo.
I really hope they complained about that vet. Thats unbelievable that he didnt test for parvo, especially if she had diarreah you can LOOK at diarreah and tell if its a parvo dog by the color. And with her coughing and just having come from the shelter? He should be fired over that, that's a no-brainer diagnosis. They should at least get their money back.
Shes adorable, glad to hear she made it!