Autism spectrum disorders (ASD) are a group of neurodevelopmental disorders characterised by significant deficits in social communication and a pattern of restricted and repetitive behaviours and interests. Recently, sensory integration problems, specifically sensory hyper- and hyper-reactive behaviours, have been included in the international classifications of diseases as a symptomatology of ASD. Sensory integration problems in autism affect sensory modulation but are also the origin of other proprioceptive and vestibular difficulties related to postural control and balance. This article presents a tool that serves both as an intervention program and as an observation rubric for balance improvements, by using horses as an intervention tool. Horses are used because they provide an emotional relationship justified by biophilia and, in addition, their movement and cadence promote the improvement of balance. Therefore, the aim of this work is to present the design and validation of an instrument (rubric) to be used with a group of students with ASD. The methodology used for validation comprises two parts. On the one hand, the logical review carried out by a group of experts, who answered a questionnaire on the quality of the proposed items. Agreement among the judges was measured with the Fleiss Kappa Concordance Coefficient, which showed an agreement of 85.71%. On the other hand, and subsequently, the empirical review was carried out with a sample of children with ASD. Cronbach's Alpha indicated an overall reliability of the scale of 0.978, thus suggestingthe internal robustness of the questionnaire. Finally, the results of its use showed the effectiveness of the validated instrument, as it was succesfully used to carry out the assessment and evolutionary follow-up of the balance in the children participating in the sample under study.