Which chemical constituents from dog feces are involved in its food repellent effect in sheep?

This study is an attempt to identify the active chemicals (signal) of the odor of dog feces that suppress feeding in domestic sheep. The repellent effects of the odors of dog, wolf, pig, and sheep feces (potential predator and nonpredator species) were assessed on sheep, using a food-choice situation. The odors of wolf and dog feces has the highest repellent effect. A total pentane extract of dog feces was split by micropreparative gas chromatography and the fractions obtained were analyzed and presented to sheep in a food-choice situation. The quantitatively major constituents of the pentane extract, identified by gas chromatography-mass spectrometry, are indole nad fatty acids. In food repellency tests, indole had no repellent effect. The active odorous signal contained in dog feces appears to consists of fatty acids mixed with neutral compounds acting synergically. These experiments underline the complexity of this biological signal and constitute a first step in the development of a practical repellent for ungulates.