The effect of insect bite hypersensitivity on the movement activity and behaviour of the horse

Abstract: It is well known that IBH in horses causes itching which in turn can lead to open wounds. The suffering and pain related to an open wound is relatively obvious, but less is known about how itching affect the welfare in the horse. The aim of this study was to investigate IceTag® accelerometers reliability to detect steps (n), lying (t) and lying bouts using two horses kept - and video filmed in boxes for one night (validation study). The aim was also to compare the movement activity of horses with IBH with non – affected horses using IceTags (IBH study). A higher movement activity, a lower lying time and a higher frequency of itching behaviours in horses with IBH compared to controls was hypothesised. Direct observations were performed to com-pare behaviours between horses with IBH and controls and to investigate the IceTags reliability to detect steps (n) and lying bouts. In total 11 horses of different breeds including six with known IBH and five controls were investigated. The horses were kept in paddocks and equipped with one IceTag on the hind leg and one at the neck for a study period of approximately seven days. Direct observations were performed in the morning and in the evening for 30 minutes and in total six times per horse. When comparing IceTag data with video recordings from the validation study, 43 – 99.7 % of the lying bouts recorded by IceTags were found to be false. Only small differences were found for steps (n) and lying (t) between IceTag data and video recordings. In the IBH study, IceTags placed at the hind leg recorded a mean lying time of 6.5±1.7 % of the study period (IBH – affected horses) versus 5.5±1.9 % (con-trols). IBH – affected horses performed in average and in total 15.5±3.9 lying bouts compared to 20.6±.6.4 in controls during the study period. For the approximately seven days study period, all horses included in the study had a mean motion index of 143 218, which is a measurement of the animal’s overall activity measured from three different dimensions. For the same period, mean motion index of the head and neck when horses were standing still was 3.14 for IBH – affected horses and 1.425 for controls. No significant differences were found in motion index, steps (n), lying (t), number of lying bouts and head and neck activity between IBH – affected horses and controls. According to direct observations, both groups showed a similar time budget. IBH – affected horses were found to perform in average – and total 78 itching behav-iours and behaviours that was considered to occur due to irritation for biting insects. The corresponding number for controls was 96.2 and was not significantly higher than the number for horses with IBH. In conclusion, no differences in movement activity and behaviour were found between IBH – affected horses and non – affected horses. IceTags placed at the hind leg of the horse were able to detect reliable data of steps (n) and lying (t) but overestimated number of lying bouts. In future studies, larger sample sizes and/or monitoring horses without protective clothing is suggested.