Development of odor-guided behavior in Wistar and Sprague-Dawley rat pups.

The odor of home-cage shavings attracts Sprague-Dawley and Wistar pups 3-4 days old. Attraction increases during postnatal week one in both strains. Lemon odor repels Sprague-Dawley pups 3 and 8 days old equally, while Wistar aversion to lemon increases during the first postnatal week. Shavings from the nests of strange litters 4 or 8 days old attract Sprague-Dawley pups 4 but not 8 days old equally. Sensory changes appear to underlie Sprague-Dawley response development, while locomotor and sensory changes may mediate Wistar response ontogeny.