Feline Pain Scales: Glasgow CMPS-Feline and the Feline Grimace Scale
How to score acute pain in cats with the Glasgow CMPS-Feline and the Feline Grimace Scale, with intervention levels, a worked example and when not to score.
The two most studied acute pain scales for cats are the Glasgow Composite Measure Pain Scale for cats (CMPS-Feline) and the Feline Grimace Scale (FGS). The CMPS-Feline combines behaviour items with two facial expression items for a maximum of 20, and a score of 5 or more means the cat needs analgesia. The FGS scores five facial features from 0 to 2 each, and a total above 0.39 out of 1.0 (about 4 out of 10) signals the need for rescue analgesia.
Quick Reference
- Glasgow CMPS-Feline: maximum 20, analgesic intervention level 5/20 or higher.
- Earlier rCMPS-F (no facial items): maximum 16, painful at 4/16 or higher.
- Feline Grimace Scale: 5 action units, each 0 to 2, cut-off above 0.39 of 1.0.
- Both are for acute pain. Neither is designed for chronic pain such as osteoarthritis.
- Do not score a cat that is sleeping, eating, grooming or playing.
Why Cats Need Their Own Pain Scales
Cats do not show pain the way dogs do. A painful cat is more likely to sit still, hide, stop grooming and lose interest in food than to cry or guard a limb. The Colorado State University feline form notes that early signs are often subtle in hospital and more likely to be noticed by the owner at home.
In a University of Glasgow study, 68 observers looked at photographs of painful and pain-free cats. Only 13 percent of them could correctly pick out more than 80 percent of the painful cats. That result is why researchers built structured tools, and why the newer tools pay close attention to the face.
Dog scales do not transfer to cats. Use a tool that was developed and tested in cats, and use it exactly as published.
Glasgow Composite Measure Pain Scale for Cats (CMPS-Feline)
How it was developed
The Glasgow group first published a behaviour-based cat scale, the revised CMPS-F (rCMPS-F). It contains six questions covering the cat's overall appearance, its response to interaction and its response to palpation of a potentially painful area. It has a maximum of 16, and a score of 4/16 or more was used to define a painful cat. Its sensitivity was moderate, with a misclassification rate of 26.7 percent.
To improve it, the group developed a simple facial scale based on ear position and the shape of the muzzle. In the 2014 development work, standardised mouth and ear measurements together separated painful from pain-free cats in 98 percent of cases. A cartoon-style picture scale was then drawn from these images.
The definitive CMPS-Feline embeds that three-point facial scale, for ears and muzzle, inside the behaviour questions. The total is the sum of all answers, with a possible maximum of 20.
The intervention level: 5 out of 20
Reid and colleagues tested the CMPS-Feline in 119 cats at three university veterinary schools, four general practices and two charity clinics. A veterinary nurse or technician scored each cat, and a veterinarian who did not know the score decided whether the cat needed analgesia. With the intervention level set at 5 and above, 82.4 percent of cats were classified correctly. The misclassification rate fell to 17.6 percent, compared with 26.7 percent for the older rCMPS-F.
In practice, a total of 5/20 or higher means the cat should be reassessed by the veterinarian and given analgesia according to the plan. Rescore after the drug has had time to work.
Do not mix up the numbers
Dog CMPS-SF: 6/24, or 5/20 without mobility. Cat CMPS-Feline: 5/20. Older cat rCMPS-F: 4/16. If a question gives a cat a score out of 20, the action point is 5.
The Feline Grimace Scale (FGS)
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The Feline Grimace Scale was developed at the Université de Montréal and published in Scientific Reports in 2019 by Evangelista and colleagues. It scores only the face, which makes it fast. The developers describe it as usable by veterinary professionals and by cat owners.
The five action units
| Action unit | What a painful change looks like |
|---|---|
| Ear position | Ear tips pulled apart and rotated outwards |
| Orbital tightening | Narrowed eyes, eyelid gap less than half the eye width, or tightly closed (squinted) eyes |
| Muzzle tension | Muzzle flattened and stretched from round to elliptical |
| Whiskers change | Whiskers moved forward, away from the face, as if spiked |
| Head position | Head below the shoulder line or tilted down, chin toward the chest |
How FGS scoring works
Each action unit is scored 0 (absent), 1 (moderately present, or you are unsure) or 2 (obviously present). If an action unit cannot be seen, it is marked "not possible to score" and left out. The total is the sum of the scores divided by the maximum possible score for the units you scored. With all five units scored, the maximum is 10, so 4 out of 10 gives 0.4.
In the validation study, the cut-off for rescue analgesia was a total above 0.39 out of 1.0. It gave a sensitivity of 90.7 percent and a specificity of 86.6 percent against the rCMPS-F. The FGS correlated very strongly with the rCMPS-F (rho 0.86), and scores fell after cats received analgesics.
Worked example
A cat with suspected pancreatitis has ears rotated outwards (2), squinted eyes (1), a tense muzzle (1) and its head level with its shoulders (0). Its whiskers are hidden against the cage wall, so that unit is "not possible to score". The sum is 4 out of a possible 8, which is 0.5. That is above 0.39, so report the score and give analgesia as ordered.
When not to use the FGS
- Do not score a cat that is sleeping. Make sure it is truly asleep and not feigning sleep because of pain.
- Wait until the cat has finished grooming, eating or playing.
- Do not use it for chronic pain such as osteoarthritis. The developers state it was validated for acute pain only.
- Expect a 1 or 2 point difference between observers. If the cat still looks uncomfortable at a low score, reassess and tell the veterinarian.
In the original study, cats were filmed undisturbed in their cages, with no staff present, after a short settling period. Observing from a distance before you open the door gives you the most natural expression.
Other Feline Pain Tools You May See
CSU Feline Acute Pain Scale. A 0 to 4 descriptive form with a body map. Published testing found moderate to good reliability but weak agreement with the CMPS-Feline. See our guide to the Colorado State University pain scales.
UNESP-Botucatu multidimensional composite pain scale. A validated behaviour-based scale for cats, cited in the FGS paper alongside the Glasgow tool. The FGS authors point out that its validity was tested for a single type of painful stimulus, ovariohysterectomy.
Comparing the Main Feline Scales
| Scale | What you score | Range | Action point |
|---|---|---|---|
| Glasgow CMPS-Feline | Behaviour, interaction, palpation, ears and muzzle | 0 to 20 | 5 or more |
| Feline Grimace Scale | Five facial action units only | 0 to 1.0 (0 to 10) | Above 0.39 |
| CSU Feline Acute Pain Scale | Behaviour, palpation, body tension, body map | 0 to 4 | 2 or more: reassess plan |
What the VTNE Expects
The Pain Management and Analgesia domain has 10 of the 150 scored VTNE items. The task statements include recognising the need for analgesia and helping carry out the pain management plan. For cats, expect questions that test whether you know that quiet, hiding or inappetent cats may be in pain, that facial changes such as squinting and flattened, rotated ears are pain signs, and which score triggers analgesia on each scale. For drug choices and multimodal plans, review the pain management study guide.
Related Resources: Pain Scoring Systems Overview · Glasgow Pain Scale for Dogs · Pain Management Practice Questions · Anesthesia Study Guide
Frequently Asked Questions
What is the Glasgow feline composite measure pain scale?
It is the cat version of the Glasgow scale, the CMPS-Feline. It combines behaviour questions with ear and muzzle images for a maximum score of 20. A score of 5 or more means the cat needs analgesia.
What score on the Feline Grimace Scale needs pain relief?
A total above 0.39 out of 1.0. With all five action units scored, that is 4 out of 10 or more.
Can owners use the Feline Grimace Scale?
The developers say it can be used by veterinary professionals and by cat owners. They also warn owners not to give any medication without veterinary advice, because some human painkillers can kill cats.
Can the Feline Grimace Scale assess arthritis pain?
No. It was validated for acute pain only and should not be used for chronic pain such as osteoarthritis.
Can I use the dog Glasgow scale on a cat?
No. The dog short form was developed and validated in dogs. Use the CMPS-Feline or the FGS for cats.
Key Takeaways
- Glasgow CMPS-Feline: maximum 20, give analgesia at 5 or more.
- FGS: ears, eyes, muzzle, whiskers and head, each 0 to 2, act above 0.39.
- Leave out FGS units you cannot see and divide by the maximum for the units scored.
- Do not score sleeping, eating or grooming cats.
- Both tools are for acute pain, not chronic pain.
Check What You Know
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- Reid J, Scott EM, Calvo G, Nolan AM. Definitive Glasgow acute pain scale for cats: validation and intervention level. Veterinary Record. 2017;180(18):449. doi.org/10.1136/vr.104208
- Holden E, Calvo G, Collins M, et al. Evaluation of facial expression in acute pain in cats. Journal of Small Animal Practice. 2014;55(12):615-621. doi.org/10.1111/jsap.12283
- Evangelista MC, Watanabe R, Leung VSY, et al. Facial expressions of pain in cats: the development and validation of a Feline Grimace Scale. Scientific Reports. 2019;9:19128. PMC6911058
- Université de Montréal. Feline Grimace Scale and FAQ. felinegrimacescale.com and FAQ
- Shipley H, Guedes A, Graham L, et al. Preliminary appraisal of the reliability and validity of the Colorado State University Feline Acute Pain Scale. Journal of Feline Medicine and Surgery. 2019;21(4):335-339. doi.org/10.1177/1098612X18777506
- Hellyer PW, Uhrig SR, Robinson NG. CSU Feline Acute Pain Scale. 2006. Form (PDF)
- AAVSB. VTNE Candidate Information Handbook. aavsb.org