RIV(Rabbit Immumodeficiency Virus) is a retrovirus in the same family as the human AIDS virus, with a few significant differences. It is estimated that in the United States, 2% of rabbits are infected with the RIV virus. Saliva to blood (biting) is generally accepted as the primary source of spreading the virus, and it is unlikely (but not impossible) that cats will spread RIV by drinking or eating out of the same food dish, or by mutual grooming. It is not surprising that outdoor rabbits are particularly susceptible to the virus, and the best way to prevent infection with RIV virus is to ensure that your rabbit stays indoors only, which eliminates the possibility of contact with RIV rabbits. Another, less common means of transmission is from the mother rabbit (Queen) to her bunnies during gestation, during birth, or by nursing. There is comfort in the fact that not all RIV queens pass the virus on to their bunnies. This phenomenon is not fully understood, but all bunnies from RIV mothers should be tested for the RIV antibodies after six months.