RELIABILITY AND ACCURACY
OF FACIAL EXPRESSIONS
FOR ASSESSING PAIN IN MICE
 What
do we know about facial expressions ?
Inheritance
Similarities between
Man and animals
(Darwin, 1872)
Tool for assessing emotions
FACS (Facial Action Coding System)
(Ekman & Friesen, 1976)
1 facial movement = several Action Units (AUs)
 Do animals exhibit facial
expressions ?
Primates:
Ekman et al., 2002
http://scan.oxfordjournals.org/content/1/3/221/F2.expansion
Mice:
Langford D.J. et al.(2010). Coding of facial expressions of pain in the laboratory mouse. Nature
Methods 7, 447-449
Rats:
Sotocinal S.G. et al. (2011). The Rat Grimace Scale : A partially automated method for quantifying
pain in the laboratory rat via facial expressions . Molecular Pain, 7:55
 Why focusing on
facial expressions?
To study the
feasability a new
method to assess pain
in mice
To effectively assess
pain during
routinely painful
procedures
To assess the efficacy
of analgesics
The mouse oucher scale
© Charles River Limited
 Facial expressions of
pain
Definition of the MGS (Mouse Grimace Scale)
AU modification
not present
moderately visible
obvious
ORBITAL
TIGHTENING
NOSE BULGE
Langford D.J. et al.(2010). Coding of facial expressions of pain in the laboratory
mouse. Nature Methods 7, 447-449
 Facial expressions of
pain
Definition of the MGS (Mouse Grimace Scale)
AU modification
not present
moderately visible
obvious
EAR POSITION
CHEEK BULGE
Langford D.J. et al.(2010). Coding of facial expressions of pain in the laboratory
mouse. Nature Methods 7, 447-449
 Facial expressions of
pain
Definition of the MGS (Mouse Grimace Scale)
AU modification
not present
moderately visible
obvious
WHISKER
CHANGE
Langford D.J. et al.(2010). Coding of facial expressions of pain in the laboratory
mouse. Nature Methods 7, 447-449
 Standard study :
material and methods
Analysis of videos from a previous unrelated study
Day 1: Pre-op video recording
Day 2 : Bilateral vasectomy + Post-op video recording
ANALGESIA
(Carprofen
5 mg/kg SC route)
30min
TREATMENT
- Saline (n=6)
per os
- Paracetamol (n=6)
246mg/kg per os
15min
60min
BILATERAL
VASECTOMY
RECOVERY
40min
POST-OP
VIDEO RECORDING
 High Definition study: material and methods
Day 1: Pre-op video recording
Day 2 : Bilateral vasectomy + Post-op video recording
30min
TREATMENT
- Saline (n=6)
2mg/ml SC route
- Meloxicam (n=6)
20mg/kg SC route
- Bupivacaine (n=6)
5mg/kg local
infiltration
ANALGESIA
(Buprenorphine
0.05mg/kg SC route)
15min
60min
12min
BILATERAL
VASECTOMY
RECOVERY
POST-OP VIDEO
RECORDING
 Mouse Grimace Scale Method
Grabbed pictures were scored by 21 trained participants
 Standard Study : 50 pre and 50 post-surgery (25 per treatment group)
 HD Study : 30 pre and 30 post-surgery (10 per treatment group)
Each FAU was scored as follow :
Facial Coding Key
Scale
Not visible
0
Moderate
1
Obvious
2
* MGS = Average scores of all the FAUs except whiskers
=> Composite of 4 FAUs
 Results of
High Definition study
***
***
P< 0.001
P= 0.001
Non-significant
The Assessment of Post-Vasectomy Pain in Mice using Behaviour and the Mouse Grimace Scale
Leach et al., PLoS ONE, 2011
Pre-op
Saline post-op
Meloxicam post-op Bupivacaine post-op
 What can
we conclude on the MGS ?
To effectively assess
pain during
routinely painful
procedures

To study the
feasability a new
method to assess pain
in mice
+/-

To assess the efficacy
of analgesics
Mice exhibit a change in facial expressions following
vasectomy surgery
- Good results with a very little training
- But not easy to see whiskers
- Pictures number
- Practicability of the method at cage-side
Facial expressions respond to the
administration of effective analgesia
Acknowledgements
AFSTAL
&
Laboratory Animals Ltd
for financial support
Tête de caractère
Franz Xaver Messerschmidt
**
BCLAS