Read an excellent article on the challenges of recognising chronic pain by BVRSMA committee member Gwen Covey-Crump BVetMed CertVA DipECVAA MRCVS CertVetAc(IVAS) Recognised RCVS Specialist in Veterinary Anaesthesia, EBVS European Specialist in Veterinary Anaesthesia and Analgesia here:
https://veterinary-practice.com/article/the-challenges-of-recognising-chronic-pain