Modulating captive mammalian social behavior: A scoping review on olfactory treatments

Many species use olfaction as a primary form of communication. Because of this, odor signals could be a useful tool to improve captive animal welfare by reducing aggression and promoting socio-positive behavior. However, to fully gauge the potential benefits of odor manipulations, the quality of existing literature must first be evaluated. Therefore, a systematic search and scoping review was conducted to summarize prevalent methods, treatment outcomes, and modulating factors in existing literature on the effect of mammalian, intraspecies odors on non-reproductive social behavior. Results from a systematic search of three databases were included if they were published in a peer reviewed journal, used a terrestrial mammalian species, and contained original data evaluating how an odor signal from the subject species directly affected non-reproductive social behavior. All articles were screened by two researchers, data were extracted by one, and reporting quality was assessed by both using the SYRCLE risk of bias tool. Sixty-three articles were included based on this criteria. Most subjects were sexually mature, male rodents. The most common odor treatment originated from urine and aggressive behavior was measured most often. Overall, urine and saliva treatments had a variable effect on aggression, while urine most often increased scent marking and social investigation behavior. Concerningly, most articles showed unclear or high risk of bias. Data from this review highlights a need for additional research on how odor signals from sources other than urine affect behavior and how socio-positive behaviors are affected in general. Further, it emphasizes the need for more transparent reporting as the current body of literature makes it difficult to determine each experiment's quality and how much weight it should be given when interpreting outcomes pertaining to our overall understanding of olfactory communication.