Dually Noted: The effects of a pressure headcollar on compliance, discomfort and stress in horses during handling

Abstract

Horse handlers often encounter problem behaviour resulting from a lack of stimulus control. Handlers are often only 15% of the weight of horses, which evolved strong flight responses. Therefore, many riders and handlers resort to the use of "aids" to maintain control of their animals. However, there are increasing concerns about the efficacy and welfare implication of such devices, particularly when applied to sensitive facial structures. One such device is a Dually® headcollar which aims to increase compliance. Despite its popularity, little is known about the effects of this aid on behaviour or stress. The aim of the current study was to determine whether the use of a Dually headcollar improves compliance during handling and, if so, whether this might be achieved with concomitant increases in stress or discomfort. Subjects completed two novel handling tests, one wearing a Dually with a line attached to the pressure mechanism and one attached to the standard ring as a Control. Crossing time and proactive behaviour were recorded as indicators of compliance. Core temperature and the discrepancy between eye temperatures were measured using IRT before and after testing as an indicator of stress. The Horse Grimace Scale (HGS) was used to measure discomfort caused by each configuration of the device. The Dually did not result in more compliant behaviour, compared to the Control (p=0.935; p=0.538). However, the Dually configuration did result in a significantly higher HGS scores (p=0.034). This may indicate that there is an impact on animal welfare by using this device that is not justified by improved behaviour. However, IRT readings of core temperature (p=0.186) and discrepancy between the eyes (p=0.972) did not indicate the Dually increased stress in subjects. Taken together, this suggests the Dually is ineffective in naïve horses but causes increased discomfort.

Dually investigated: The effect of a pressure headcollar on the behaviour, discomfort and stress of trained horses

“…There was no significant difference between Naïve and Trained Control HGS ( Trained and Naïve horses (Table 5). (Ijichi et al, 2018). One of the limitations to the first study was that subjects had no prior training in the Dually™, therefore it could be expected that training would improve compliance.…”

“…To determine a potential effect of training on behaviour and physiology in horses wearing a Dually™ headcollar, previously collected data from 20 naïve horses who had not been trained in a Dually™ headcollar was also included (Ijichi et al, 2018).…”

“…These subjects underwent the same testing procedure over novel objects, full details of which are reported by Ijichi et al (2018). Eye temperatures, crossing times and proactive behaviour were available for these subjects, but not HRV or salivary cortisol.…”

“…However, research investigating bridles which apply pressure to similar sensitive facial structures highlights welfare concerns (Doherty et al, 2017;Fenner et al, 2016;McGreevy et al, 2012). Further, Ijichi et al, (2018) found the Dually™ did not improve compliance in naïve horses but did result in higher Horse Grimace Scale scores (HGS). However, in the previous study, subjects were naïve to the Dually™ and had not been trained to give the desired response, resulting in release of pressure.…”

“…Ocular temperature measured by infrared thermography (IRT) (Yarnell et al, 2013), heart rate variability (HRV) (von Borell et al, 2007) and salivary cortisol (Hughes et al, 2010) were measured as indicators of stress and arousal. Data from the previous study on naïve horses completing similar tests (Ijichi et al, 2018) was also included to compare the responses of trained and naïve horses. Results were compared between Control and Dually™ in Trained horses and between Naïve and Trained horses.…”