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Scientific Abstract

Pheromone/Interomone effects of behavior of foals after weaning

K. A. Guay1, M. May and J. J. McGlone
Laboratory of Animal Behavior, Physiology and Welfare
Texas Tech University, Lubbock.

The stress of weaning is stressful to both the mother and offspring. After weaning, foals vocalize, pace, increase aggression and show increased activity. This was a preliminary study to determine if calming pheromones had an effect on foal behavior immediately after the weaning process. The pig pheromone (androstenone) was shown in our laboratory to reduce head-shy behavior of horses. The rabbit maternal pheromone (2-methylbut-2-enal) was shown to reduce anxious behaviors in dogs. Both the pig and rabbit pheromones act as interomones on other species. Ten foals were selected and randomly assigned to a treatment group. Foals were from a large commercial ranch in West Texas and were weaned on a single day. Foals were 8 to 10 months of age at weaning. All subjects were stock type, ranch horses (Quarter Horse). Foals were randomly assigned a treatment (pig pheromone; PP, rabbit pheromone; RP, or Control; CON). Treatments were administered as a gel to the nose of the animal. Stress behavior such as vocalizations, pawing, fighting, head shaking, defecation, pacing and sweating were recorded for 15 min post weaning. Analysis was done by 2 X 2 Chi-square. The CON group paced more (P < 0.01) than RP or PP groups (70.8, 15.7, and 13.4 %, respectively). The RP-treated foals vocalized more (P < 0.01) compared to CON (52.0 vs. 30.0%) and CON vocalized more than PP-treated foals (30.0, 18.0%, respectively). The CON group displayed more (P < 0.001) aggressive/fighting behavior than RP and PP (59.3, 7.3, and 33.33%, respectively), and PP fought more than RP (33.33 vs. 7.3%, respectively). Our findings suggest pheromones/interomones may reduce some of the negative behavioral effects observed at weaning. The RP and PP may calm weaned horses. More research is needed to describe behavioral and physiological influences of interomones on horses in stressful situations.

Key Words: Horse, Pheromone, Interomone, Weaning