Young gyp dies mysteriously

This has nothing to do with your case but late last spring I had some sort of virus come through my yard and it only messed with a group of pups I had that we’re all about 8 months old and had their shots and walking definitions of health, my dad had a litter of beagle pups at his house which is about 500 yds from my place if that, and my cousin had a litter of bulldog pups next door, neither set of those pups had any type of shots or wormer and were all good looking, it was all the same symptoms of parvo, semi bloody stool, severe vomiting and diarrhea, I stayed on top of them and gave them Zofran in the morning before I went to work when I fed them for the vomiting, and kaopectate before work, soon as I got home and again at evening feeding when I normally feed up, this lasted 3 days, I had given a friend of mine a male as soon as they started getting sick not knowing how sick they were about to be, he didn’t give his the attention it needed and give it a 9-1 shot on top of what ever virus the dog had, and he didn’t make it, and I lost another male that was running loose that got down and laid up where I couldn’t find him and by the time I did it was to late, now all these pups were in the same age group but out of 3 different litters and had all had shots and regular wormings, this whole time pups from both my cousins and my dads dogs all somewhat intermingled at some point in time and none of those pups had any shots and were already weaned and not a single one of them ever got the least bit sick or ever missed a beat, damndest thing I’ve dealt with health wise, and why it only effect the older vaccinated pups...