I think most people can relate to not knowing. Times have changed. My one cat (Chewy) got out once, before this group started.
He was out once and apparently found a felv+ cat and had a fight. Not knowing anything about felv 3 months later he started to have trouble swallowing, got antibotics then 2 weeks later with the same problems we tested and he was felv+. The vet said to separate all the other 5 cats. I thought totally stupid considering they for 3 or 4 months were together. The sister of Chewy infact would groom him and he her and they licked tongue to tongue. None of my cats were positive but I did vaccinate. Chewy passed away not too long after. Charmed was a foster who was positive his siblings were not. They intermingled for a few months before I found out. None of them developed the vius. We also have a foster that has about 6 felv cats and 3 of them have been health and fine for about 3 yrs. Not even a cold. I truly think it has a lot to do with the strand of the virus. Carla