FIV Transmission Among Cats Still Poorly Understood

Feline Immunodeficiency Virus (FIV), in some ways is similar to HIV in humans, is a retrovirus that attacks the immune system and leaves the body vulnerable or depleted, prone to other diseases or infections. However, unlike HIV, the routes of transmission for FIV are still being studied and remain relatively unknown. Researchers know that the main mode of transmission is via bite wounds, as well as vertical or pediatric transmission (meaning in utero, intrapartum, or via milk/colostrum). However, studies of “mixed households” with cohabitating FIV-positive and FIV-negative cats have shown that infection rates are variable and somewhat unpredictable.

In this study, researchers wanted to investigate the “horizontal transmission of naturally-acquired FIV between cats in a mixed, multi-cat household and to investigate viral transmission from naturally-infected FIV-positive queens to their kittens.” They collected information from two cat-only shelters over a long-term period. They found that in a mixed household, over a period of months to years — and despite mutual grooming, mild aggression, shared food bowls, litter boxes, bedding etc. — there was no evidence of transmission of infection from FIV-positive to FIV-negative cats. They also found no evidence of vertical FIV transmission at one of the cat shelters.

If these results can be generalized, then they could have major implications for rescues and shelters that have strict policies about housing and adopting out FIV-positive cats: while the researchers noted that they did not detect any instances of horizontal transmission (which is a great sign for cohabitation), “careful management is required when cats are first introduced to one another, as the potential for agonistic interactions that could result in FIV transmission is increased.”