Inter-observer reliability of three human-horse relationship tests

The perception of humans and of the interaction with them was shown to have a major impact on horse welfare and safety of people. The aim of the study was to evaluate if trained assessors agree in their evaluation of human-horse relationship tests. Four observers with no experience in assessing equine welfare were trained to perform and score 3 standardized human-horse behavioural tests derived from literature: a modified Avoidance Distance test (AD), a modified Voluntary Animal Approach test (VAA) and a modified Forced Human Approach test (FHA). Tests were performed in the home box. A scoring system for each test was developed. Training procedure of observers consisted of giving a detailed verbal explanation of each test and scoring system, using PPT presentations with photographs and a written training guide, practical trials (video and live).They then conducted live assessments, paired with the trainer (silver standard), until each assessor consolidated his/her experience through applying the tests and the scoring system to a minimum of 5 correct repetitions in a row. After a final exam, the assessors tested 184 horses of 6 different stables, aged between 3 and 35 years (mean=10,3yrs). Assessors worked in pairs: each horse was scored live by the assessor performing the test and the other assessor observing from a distance. Observers did not talk or discuss during assessments. Kendall’s coefficient of concordance (W) for k related samples from a continuous field and Interclass Correlation Coefficient (ICC) were calculated to measure inter-observer reliability. Observers significantly agreed scoring Avoidance Distance test (W<0.05),Voluntary Animal Approach test (W<0.05; ICC=0.94) and Forced Human Approach test (ICC=0.93). Our results clearly show that inter-observer reliability in scoring human-horse behavioural tests can be achieved. Sufficient theoretical and practical training of assessors should be taken into consideration for developing standardized human-horse relationship tests.