I am often asked if horses are put under stress when they are in an electrified fence irrespective if they show no outward signs of stress. I was pleased to come across this scientific study from a Swiss University evaluating the stress levels of horses under the sort of situations they encounter.
"Most horses respect electric fences, but can they be a source of stress in their lives?
Swiss researchers have found no evidence of any stress response in horses as a result of being contained within electric fencing. It did not matter whether the enclosed area was large or small, with the smaller of the two areas assessed being no bigger than a conventional stable. Temporary electric fencing is increasingly used at some events to contain horses, providing them the opportunity to move and eat some grass.
Rupert Bruckmaier and his colleagues from the University of Bern said some concern existed that electric fencing systems could potentially affect horse behaviour, cause chronic stress and reduce the accessible space in a pasture.
Their finding may be summarised as follows;-
- No indication of stress in electrically fenced paddocks.
- Cardiovascular, endocrine, and behavioural parameters similar in all paddocks.
- Horses use less of the available area in electrically fenced and small paddocks.
- Horses avoid the area near the fence in electrically fenced paddocks.
They set out to measure stress responses in 20 horses kept in four different outdoor enclosures on pasture. They used two different-sized areas, with either wooden fencing or electric fencing.The smaller of the two sizes was 12.25 square metres – the size of a modest stable – and the larger enclosure was nearly three times that size, at 36 square metres.The researchers recorded the horses on video to later check for behavioural signs indicating stress, and determine whether there were any differences in pasture use between wooden fencing and electric fencing.The horses, aged between 6 and 18, were put through the four enclosures, with each getting 90 minutes in each one.
Periodic measurements of the animals’ heart rate and heart-rate variability were taken, and samples of saliva were also taken for cortisol analysis – all of which paint a picture of the stress response in the animals.“The total amount of stress-indicating behaviour did not differ between the two fence types,”
Salivary cortisol and heart-rate variability did not differ between the paddocks.Horses used the available area significantly less in the electrically fenced enclosures, and also in the smaller of the wooden-fenced areas.The border area – 50 centimetres – was used less both in electrically fenced and small paddocks.Horses moved less in the small and electrically fenced paddocks than in big and wooden-fenced ones. Horses rolled less in small paddocks.
Some stress-indicating behaviour tended to be more prominent in the small fenced areas, the research team noted, but they continued:
“Based on the measured physiological parameters, there is no indication for stress in electrically fenced paddocks.”
Twenty horses aged between 6 and 18 years were tested comparing two paddock sizes (12.25 m2/36 m2) either with wooden or electric fencing in order to evaluate physical and behavioural parameters. Each horse was tested in a randomised sequence in all four paddock types during 90 min per type. During the experiments the horses were continuously recorded on video for later analyses of behavioural patterns and the utilisation of the available paddock area. Additionally, periodic measurements of heart rate (HR), heart rate variability (HRV) as well as standardised salivary samplings for later cortisol determination were carried out. Horses used the available area significantly less both in electrically fenced and small paddocks (p < 0.001). The border area (50 cm) was used less both in electrically fenced and small paddocks (p < 0.001). The total amount of stress-indicating behaviour did not differ between the two fence types. Horses moved less in small (p < 0.001) and electrically fenced (p < 0.005) paddocks than in big and wooden fenced ones. Horses rolled less in small paddocks (p < 0.001). Fence contact was significantly less with electric fencing (p < 0.001). Stress-indicating behaviour tended to be more prominent in small paddocks. Salivary cortisol and HRV parameters did not differ between the paddocks but a slight tendency of alteration of the low frequency/high frequency ratio indicating stress reactions was observed with electric fencing. Based on the measured physiological parameters there is no indication for stress in electrically fenced paddocks. However horses use less of the available paddock area both in electrically fenced paddocks and small paddocks, especially by avoiding the area near the fence.