Fox urine as an aversive stimulus: modification of a passive avoidance task.

Predator urine, specifically fox urine, is a noxious but harmless olfactory stimulus. The results of previous studies have shown that fox urine is aversive to rats, and that rats react to fox urine in a similar manner as to other psychostressors. In the present study, the authors further investigated the use of fox urine as an aversive or stressful stimulus, specifically examining behavior change in open-field place-preference task. Three methods of presenting the fox urine were examined. Results indicated that fox urine decreased behavior, especially locomotion, during both fox-urine presentation and during a post-fox-urine recovery session. Data suggested that (a) there were fewer ambulatory episodes and less distance was traveled during the presentation of fox urine, regardless of presentation method, and (b) there were fewer vertical movements during fox-urine presentation when a fox-urine-laced cotton ball was set in the wood shavings than when it was placed on a bare floor or in a cup. The data suggested that fox urine may be an effective but nonharmful stimulus alternative for use in avoidance tasks.