Behavioural and physiological indicators of hoof trimming stress in restrained juvenile stable- and forest-born Konik Polski horses: A cross-sectional and longitudinal field study

Abstract

Behavioural and physiological responses are suggested indicators of horse stress. The responses can vary according to changing intrinsic factors, for example, age or habituation to human handling and restraint.

In this study, the same 53 Konik Polski horses that were born in either a forest-born (FB) sanctuary or a stable-born (SB) sanctuary were assessed for consistency in their behavioural and physiological responses over months, and the relationship between avoidance behaviour (withdrawals, head shakings, jerks, rearings, stepping and their total: AB), leaning behaviour and cardiac responses (heart rate: HR and heart rate variability HRV: SDRR and RMSSD during routine hoof trimming at 6, 12 and 18 months of age was examined. Additionally, the effect of age and birthplace on avoidance behaviour and cardiac parameters and their correlations was investigated.

The avoidance behaviour, leaning behaviour and HR and HRV parameters differed between SB and FB horses (P < 0.01). A significant effect of increasing age/habituation was found in each birth-place group at each age (both effects P < 0.01). Additionally, the correlations of and between behaviour and cardiac parameters were fairly consistent both over age and within groups. The findings indicate that physiological and behavioural markers that are frequently used may not adequately represent the stress status of restrained horses; rather, they may only represent the animals' short-term, current state. Age and prior experience are significant factors to consider when evaluating stress related to husbandry management procedures. Providing that the differences between forest and stable horses remain until 18 months old, the rearing conditions up to weaning would seem sufficient to develop a specific human reception in young horses.