The influence of early life factors on the determination of phenotypes that are vulnerable or resilient to developing stereotypies in horses

• Grant number: 22/16471-1
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Adroaldo Jose Zanella
• Grantee: Ana Carolina Dierings Montechese
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Stereotypies are repetitive and invariant behavioural patterns with no apparent function or goal which are frequently performed by individuals in conditions of compromised welfare. Although they are extensively described in horses, their causes and mechanisms are still under debate and the determining factors for resilient or vulnerable phenotype are still unknown. Abrupt weaning appears to be the starting point for the development of stereotypies in foals, and exposure to stress is a commonly suggested factor for affected individuals, however studies regarding the influence of early life factors are scarce and the determination of the relationship between the function of the hypothalamic-pituitary-adrenal axis and the performance of stereotypies is complicated by contradictory results. The objective of this project is to investigate the factors involved in the determination of vulnerability or resilience to the development of stereotypies in horses, considering known risk factors for predisposition to higher stress reactivity such as excessive fetal exposure to glicocorticoids and negative maternal-filial interactions. For this purpose, 100 Brasileiro de Hipismo foals will be followed during their first three years of life through samplings of placental tissues, umbilical cord blood, hair and saliva for assessment of concentration of cortisol and gene expression of NR3C1 (glicocorticoid receptor) and HSD11B2 (11-²-Hydroxysteroid dehydrogenase), as well as behaviour observations of mare-foal interactions, behavioural responses to abrupt weaning and performance of abnormal behaviours including stereotypies. (AU)