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Evaluation of facial expression in acute pain in cats

Holden, E; Calvo, G; Collins, M; Bell, A; Reid, J; Scott, E M; Nolan, Andrea M


E Holden

G Calvo

M Collins

A Bell

J Reid

E M Scott


To describe the development of a facial expression tool differentiating pain-free cats from those in acute pain.
Observers shown facial images from painful and pain-free cats were asked to identify if they were in pain or not. From facial images, anatomical landmarks were identified and distances between these were mapped. Selected distances underwent statistical analysis to identify features discriminating pain-free and painful cats. Additionally, thumbnail photographs were reviewed by two experts to identify discriminating facial features between the groups.
Observers (n = 68) had difficulty in identifying pain-free from painful cats, with only 13% of observers being able to discriminate more than 80% of painful cats. Analysis of 78 facial landmarks and 80 distances identified six significant factors differentiating pain-free and painful faces including ear position and areas around the mouth/muzzle. Standardised mouth and ear distances when combined showed excellent discrimination properties, correctly differentiating pain-free and painful cats in 98% of cases. Expert review supported these findings and a cartoon-type picture scale was developed from thumbnail images.
Initial investigation into facial features of painful and pain-free cats suggests potentially good discrimination properties of facial images. Further testing is required for development of a clinical tool


Holden, E., Calvo, G., Collins, M., Bell, A., Reid, J., Scott, E. M., & Nolan, A. M. (2014). Evaluation of facial expression in acute pain in cats. Journal of Small Animal Practice, 55, 615-621.

Journal Article Type Article
Acceptance Date Sep 15, 2014
Online Publication Date Oct 30, 2014
Publication Date 2014-12
Deposit Date Nov 25, 2014
Publicly Available Date May 1, 2016
Journal Journal of Small Animal Practice
Print ISSN 0022-4510
Electronic ISSN 1748-5827
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 55
Pages 615-621
Keywords Facial expression; Cats; facial features; pain assessment;
Public URL
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