Rest Patterns Assessment in Horses Using Electroencephalogram (EEG) and Characterization of an Ethogram to Identify Non-NREM Sleep-Related Inactivity While Standing

• Grant number: 24/20303-2
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2025
• End date: October 31, 2028
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Raquel Yvonne Arantes Baccarin
• Grantee: Ângela Perrone Barbosa
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Society's concern with the welfare and ethics in the use of horses in equestrian sports is increasingly present, especially after Olympic periods, when equestrian sports gain visibility in the media and attract an audience that is not familiar with the sport. Consequently, studies focusing on animal welfare have grown to ensure the safe participation of equine athletes in competitions, both from a sanitary and animal welfare perspective. In this context, studies on equine sleep have shown their importance for welfare and athletic performance. Horses have a polyphasic sleep pattern, alternating between REM (Rapid Eye Movement) and NREM (Non-Rapid Eye Movement) phases, totaling about three hours of sleep per day, mainly at night. Sleep is a physiological activity for energy conservation, while non-sleep-related inactivity may be associated with negative affective states and decreased well-being in mammals. The concept of inactivity has been recently implemented, with higher prevalence of inactivity often being associated with boredom, unstimulating environments, and lack of well-being; and little inactivity is associated with frustrations due to the lack of opportunity to demonstrate the species' behavioral repertoire, causing increased locomotor activity and frequency of stereotypic behaviors. The objective of this study is to construct an ethogram capable of characterizing inactive behaviors in horses in different environments and distinguishing them from beneficial behaviors, namely NREM sleep while standing. To this end, the electroencephalogram (EEG) examination will guide the construction of an ethogram that is effective in differentiating inactivity from NREM sleep while standing. In a subsequent stage, we will test the ethogram's efficiency in identifying behavioral changes, namely inactivity, in horses subjected to husbandry changes or REM sleep deprivation and monitored by filming. In the final stage, we will test the efficiency and effectiveness of the ethogram in hospitalized horses, to assess both inactivity and NREM sleep, as a method for evaluating hospital welfare. Thus, the study will be conducted in four phases: in the first phase, eight horses will be monitored through nighttime recordings in the stall during the EEG exam to correlate different behaviors with NREM sleep or inactivity. In the second phase, after a 45-day rest period, without leaving the stall, these same horses will be filmed, and the recordings evaluated to identify stereotypic or inactive behaviors. Then, they will begin daily management and be reassessed at the end of the experiment period. In the third phase, with the constructed ethogram, videos of 10 horses subjected to REM sleep deprivation will be analyzed, and the observed behaviors compared with control periods. During this phase, other horses diagnosed with REM sleep deprivation will be filmed for 36 hours, and the behaviors evaluated using the same ethogram. In the final phase, the ethogram will be applied to 20 hospitalized horses, which will be filmed for at least five days. These latter will use Inertial Measurement Units (IMUs) on the right metacarpophalangeal joint to monitor movements and the number of times they lie down. The data will be correlated with sleep deprivation, inactivity, and stereotypic behavioral changes. Our hypothesis is that many horses have periods of inactivity associated with negative affective states and lack of welfare, and that with an ethogram, both inactivity and sleep deprivation disorders can be more easily identified and differentiated.