Evangelista et al. Facial expressions of pain in cats: the development and validation of a Feline Grimace Scale. Sci Rep 9, 19128 (2019)


  • Pain-induced behavioral changes are unique in cats and can be subtle


  • The instrument has been developed and validated to be used by veterinarians
  • It is currently under testing for use by other veterinary care professionals


  • The Feline Grimace Scale is a simple method of acute pain assessment. It is based on changes in facial expressions and can be easily and quickly performed in the clinical setting
  • It differentiates painful and non-painful cats and response to analgesic treatment


  • The FGS is used for acute pain assessment in cats with medical, surgical or oral pain, etc.
  • Pain assessment should be performed as often as needed and on a case-by-case basis



  • There are five action units (AU): ear position,
    orbital tightening,
    muzzle tension,
    whiskers position and head position
  • Each unit is scored:
    0 (absent),
    1 (moderately present) or
    2 (present)
  • The final score is calculated by the sum of scores divided by the maximum possible scores
  • Analgesic treatment is suggested when the final score is 4/10 or 0.4/1.0

0 = AU is absent

  • Ears facing forward
  • Eyes opened
  • Muzzle relaxed (round shape)
  • Whiskers loose and curved
  • Head above the shoulder line

1= AU is moderately present*

  • Ears slightly pulled apart
  • Eyes partially opened
  • Muzzle mildly tense
  • Whiskers slightly curved or straight
  • Head aligned with the shoulder line

    *The score of 1 can be also given when there is uncertainty over the presence or absence of the AU

2 = AU is markedly present

  • Ears flattened and rotated outwards
  • Squinted eyes
  • Muzzle tense (elliptical shape)
  • Whiskers straight and moving
  • Head below the shoulder line
    or tilted down (chin towards the chest)