Feline Immunodeficiency Virus I just found out the cat I had hoped to take to the vet, and just have it wormed and vaccinated can't be a house cat because it has Feline Immunodeficiency Virus. I am really disappointed about this. I actually sat in my van and cried about it. Poor little thing. It looks soooooo healthy, weighs 12 lbs and kicks the crap out of the other strays that hang around our barn too.