Research resource:

Dyson, S., Thomson, K., Quiney, L., Bondi, A. and Ellis, A.D. (2020). Can veterinarians reliably apply a whole horse ridden ethogram to differentiate nonlame and lame horses based on live horse assessment of behaviour? Equine Veterinary Education 32, (10) pp. 112-120. (Not an open source article.)

Link to the "Horses and People" article which lists the ethogram: https://horsesandpeople.com.au/ridden-horse-ethogram-helps-identify-pain/