Frequently asked questions The Feline Grimace Scale (FGS) for veterinarians
See below common questions regarding how to proceed in specific situations and/or tips on clinical decision-making.
Click here for the most up to date scientific information on the FGS.
Cat is grooming, eating or playing
Wait until these activities are finished for FGS scoring.
Cat scored 4/10, but I am uncertain if it is indeed painful
Reassess the cat in 15-20 minutes.
I administered analgesics before surgery and when I scored the cat 45 minutes after surgery, the scores were 9/10.
FGS scores of 9/10 are high and the cat is probably painful requiring additional administration of analgesics. Analgesics are frequently required before, during and after surgery for optimal analgesia. See the ISFM guidelines on acute pain management.
What is the cut-off score for administration of rescue analgesia?
Rigorous statistical analysis from scientific studies with the FGS indicates that cats scoring ≥ 4/10 are likely to be in pain requiring the administration of rescue analgesia.
Are there automated means to see if my cat is painful using the FGS? For example, can I take a picture of my cat and automatically know the if he/she is painful?
No. Some companies are advertising the use of the Feline Grimace Scale for automated assessment of cats’ emotions. However, the FGS was scientifically validated for evaluation of acute pain only and it should not be used for evaluation of other emotions (e.g. happiness or sadness). Our laboratory does not have any relationship with these companies and we are currently working on scientifically-sound methods to produce a robust, science-based tool with high specificity, sensibility and precision followed by peer-reviewed publications.
Cat is shy or fearful
Attempt to score the cat from a distance, if possible. Consider using fear-reducing and feline-friendly handling techniques for all patients to facilitate pain assessment. In our experience, shy or feral cats may present changes in facial expressions that may be due to anxiety and fear, and not always pain.
Cat scored 3/10, but I think it could be painful
Reassess the cat in 15-20 minutes.
Cat scored 6/10 and I just administered an intramuscular injection of opioid
Reassess the cat in 30-40 minutes. The FGS scores should be reduced. If FGS scores have not decreased, a second dose of rescue analgesia might be required or a change in analgesic plan should be considered.
Can I assess pain in a patient by only looking at a photo?
Research shows good agreement between real-time and image scoring. However, you must consider:
1) The image must be representative of the cats’ facial expressions over several minutes. Changes in facial expression related to pain do not occur once in a split second. Changes in facial expressions are dynamic and may occur due to other things unrelated to pain (e.g. background noise, anxiety and fear).
2) The clinical context, cat’s history and physical examination must be evaluated along with the image. Cats with acute pain frequently show other changes in behavior associated with pain (e.g. decreased activity, decreased interest in the surroundings, decreased appetite, etc.).
Can I use the FGS to evaluate pain in other species?
No. The FGS was validated for use in cats only. Grimace scales for evaluation of pain in other nonhuman mammals are available and have been recently reviewed. Click here for more information.
Is there a phone application for the FGS?
I want to learn more about pain management in cats
Numerous resources about pain management in cats are freely available on this website and across the internet. For example, you can read the 2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats.