Do odors from different cats induce equivalent unconditioned and conditioned responses in rats?

Since cats are predators of rats and mice, interest in the consequences of exposure to cat-associated odors has increased in the last decade, particularly regarding the development of putative animal models of post-traumatic stress disorder (PTSD). Although in the literature there are some comments on the variability of the effects depending on the individual cat used, there are no reports on this subject. In the present study, we demonstrated, using male Sprague-Dawley rats and cloths impregnated with fur/skin odors from three different cats (one ovariectomized female and two intact males), that the unconditioned endocrine (release of corticosterone) and behavioral (inhibition of activity and avoidance of the cloth area) responses to the presence of the cat odors were statistically significant and similar among the three cats. The conditioned behavioral response to a clean cloth, studied 7 days after the initial exposure to odors, was also evident with the three cats, with minor differences among them. In contrast, only the fur odor from one of the male cats clearly increased anxiety-like behavior in the elevated plus-maze 6 days later. These data indicate that: (i) evaluation of unconditioned and conditioned responses to cat odors does not appear to strongly predict long-lasting increases in anxiety-like behavior; and, therefore, both types of responses are partially dissociated; and (ii) differences among cats mainly affected the induction of long-lasting changes in anxiety-like behavior. The ultimate reasons for these differences are not known, but their characterization is critical for a proper understanding of putative PTSD models.