Sharing an environment with sick conspecifics alters odors of healthy animals

• Published in: Scientific reports Vol. 8; no. 1; pp. 14255 - 13
• Main Authors: Gervasi, Stephanie S., Opiekun, Maryanne, Martin, Talia, Beauchamp, Gary K., Kimball, Bruce A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.09.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 631/92/604; 64; 64/60; 704/158/856; Animals; Avoidance behavior; Avoidance Learning - physiology; Behavior; Behavior, Animal - physiology; Body odors; Conspecific odors; Conspecifics; Endotoxins; Generalization Trials; Healthy Conspecifics; Humanities and Social Sciences; Illness Behavior - physiology; Immune response; Lipopolysaccharides; Male; Mathematical models; Mice; multidisciplinary; Neuroendocrine system; Odorants - analysis; Odors; Olfactory discrimination; Olfactory discrimination learning; Science; Science (multidisciplinary); Sick Mice; Smell - physiology; Social Behavior; Statistical models; Urinary Volatiles; Urine; Urine Donors; Volatiles; Healthy Conspecifics; Generalization Trials; Urine Donors; Sick Mice; Urinary Volatiles
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-32619-4

Body odors change with health status and the odors of sick animals can induce avoidance behaviors in healthy conspecifics. Exposure to sickness odors might also alter the physiology of healthy conspecifics and modify the odors they produce. We hypothesized that exposure to odors of sick (but non-infectious) animals would alter the odors of healthy cagemates. To induce sickness, we injected mice with a bacterial endotoxin, lipopolysaccharide. We used behavioral odor discrimination assays and analytical chemistry techniques followed by predictive classification modeling to ask about differences in volatile odorants produced by two types of healthy mice: those cohoused with healthy conspecifics and those cohoused with sick conspecifics. Mice trained in Y-maze behavioral assays to discriminate between the odors of healthy versus sick mice also discriminated between the odors of healthy mice cohoused with sick conspecifics and odors of healthy mice cohoused with healthy conspecifics. Chemical analyses paired with statistical modeling revealed a parallel phenomenon. Urine volatiles of healthy mice cohoused with sick partners were more likely to be classified as those of sick rather than healthy mice based on discriminant model predictions. Sickness-related odors could have cascading effects on neuroendocrine or immune responses of healthy conspecifics, and could affect individual behaviors, social dynamics, and pathogen spread.