Litster A. Transmission of feline immunodeficiency virus (FIV) among cohabiting cats in two cat rescue shelters. The Veterinary Journal 2014;201:184-8.
Housing of FIV positive cats in shelters and foster home and adoption of these cats to private homes frequently poses a conundrum to cat welfare workers, as these animals are frequently healthy and have normal lifespans, but could have the potential to transmit the disease to FIV seronegative cats present in the shelter or housing situation. Another concern is the frequency of vertical transmission of FIV from seropositive queens to their kittens. In both situations, FIV positive cats and seronegative cats exposed to them may be euthanized without good reason. It is generally known that FIV is commonly transmitted between cats via bite wounds, and FIV may also be transmitted through parenteral routes. Mucosal transmission between individuals is relatively inefficient compared to feline leukemia virus or human immunodeficiency virus (HIV).
In the first portion of this study (shelter 1), 138 cohabiting cats, all spayed and neutered, were followed over a period of years. Initial testing demonstrated that 130 cats were FIV seronegative and 8 were FIV seropositive. Only one of the FIV negative cats went outdoors, and this particular cat was also aggressive towards the other cats but no skin wounds were noted on cats he engaged with. Cats in this shelter, a privately owned rescue in a house operated by a single caregiver, had unrestricted access to each other. They had no history of FIV vaccination and shared litterboxes, food, water, dishes, and bedding. The second round of retrovirus testing was performed on 45 of the seronegative cats and 5 of the seropositive cats at a median 28 months after the first (range 1 month-8.8 years) showed no changes in the results. At median 38 months after the first test (range 4 months-4 years) 4 of the seronegative cats and one of the seropositive cats had maintained their original status. In 33 cats tested for FIV using both ELISA and PCR, no cats were found to be FIV ELISA negative and PCR positive.
The second part of the study was performed in a private, feline-only foster care situation (shelter 2), involving 5 FIV seropositive queens and their nursing kittens. The queens had no access to other FIV positive cats and had had no known FIV vaccinations. FIV serology was performed on all 19 kittens after weaning; all were seronegative.
Limitations of this study included the small number of cats at shelter 1 who could be followed longitudinally due to an active adoption program at this shelter. In the shelter 2 study, kittens were tested for FIV after weaning but were not followed with FIV testing subsequently to see if they seroconverted later on. Also, a higher ratio of FIV positive to FIV negative cats in a cohabitation situation might increase the risk of fighting and transmission of FIV, especially if the cats are stressed and have few opportunities to escape from each other. Based on the results of this study, shelter personnel may co-house already neutered FIV positive and negative cats and adopt FIV positive cats to homes where FIV negative cats already live with a high degree of confidence that FIV is unlikely to be transmitted to seronegative cohabiting cats. Most cats who cohabit in a home or shelter are unlikely to inflict bite wounds on each other that would facilitate transmission of FIV, but careful monitoring and separation of cats who fight and bite is essential. There is no need to euthanize healthy FIV positive cats if they can be adopted to homes where they are kept indoors and owners are willing to be vigilant regarding their health. [PJS]