Effects of feline immunodeficiency virus on cognition and behavioral function in cats.

Experimental intravenous challenge of 8-week old cats with the Maryland isolate of feline immunodeficiency virus, Maryland isolate (FIV-MD) was investigated for its effects on cognitive and behavioral function at 12 months postinfection. Six cats infected with FIV-MD were compared with age-matched controls on several behavioral measures. These measures included an open field observation, locomotion tests, traversing planks of various widths for food reinforcement, and a spatial learning task. No group differences were observed on any measure of locomotion. Differences were present with exploratory and stationary activity in the open field observation, with infected cats exhibiting higher levels of exploratory activity and in less stationary activity compared with that of control cats. In the plank-walking experiment, infected cats were less able to successfully cross progressively narrower planks compared with control animals. A holeboard paradigm was constructed to test spatial learning and memory, in which cats were required to locate food reinforcement based on position in the holeboard array. As a group, FIV-infected cats committed more reference (exploring an unbaited cup) and working memory (returning to a previously visited baited cup) errors than control cats. The main difference demonstrated was a higher activity level and associated distractibility in FIV-infected cats that appears to be related to their overall deficient performance when learning new tasks. These results indicate that behavioral function is altered and cognition is quantitatively impaired in FIV-infected cats.