Published by: Ingrid King. Last Updated on: June 26, 2023 by Crystal Uys


Cats are masters at masking pain. Their ability to hide pain goes back to their wild origins. In the wild, a sick animal becomes prey. While acute pain may be more obvious, chronic pain from conditions such as arthritis can be challenging to discern for even the most dedicated cat parent. Even veterinarians often overlook signs of feline pain.

The Feline Grimace Scale

A new scoring system that interprets changes in facial expression could help provide guidance to veterinarians and eventually cat parents.

Dr. Paulo Steagall, an associate professor of veterinary anesthesia and analgesia at the University of Montreal, developed the Feline Grimace Scale through an observational, case-controlled study of 31 privately owned cats in pain and 20 pain-free control cats.

The researchers categorized and tested five facial actions indicative of pain in cats: ear position, tightening of the eyes, muzzle tension, whisker position, and head position. Next, two observers independently compared screenshots of the two groups of cats (painful and pain-free) to evaluate differences in facial expressions. The researchers then categorized, tested, and scored five “facial action units” (ears, eyes, muzzle, whiskers, head) that signal pain in cats:

  • Ear position — Ears facing forward, ears slightly pulled apart, or ears flattened and rotated outward
  • Orbital tightening — Eyes opened, eyes partially opened, or eyes squinted
  • Muzzle tension — Muzzle relaxed (round), muzzle mildly tense, or muzzle tense (elliptical)
  • Whisker position — Whiskers loose and curved, whiskers slightly curved or straight, or whiskers straight and moving forward
  • Head position — Head above the shoulder line, head aligned with the shoulder line, or head below the shoulder line or tilted
Images of cats in which pain was absent, moderately present, or markedly present (courtesy of Dr. Paulo Steagall via

Scores were then evaluated prior to and after receiving pain control medications.

According to an article on the AAHA website, the researchers are currently testing the reliability of the tool when applied by veterinary care professionals other than veterinarians. My experience working in veterinary clinics has been that support staff are often the ones who alert veterinarians to pain, and I wouldn’t be surprised if vet support staff was already using cats’ facial expressions as an indicator of pain long before this study.

The results of the study were published in the journal Scientific Reports.

The Feline Musculoskeletal Pain Index (FMPI)

A tool that helps cat parents assess pain in their cats at home is already available.

Feline Musculoskeletal Pain Index (FMPI, developed by, is a product of the North Carolina State University (NCSU) College of Veterinary Medicine’s Comparative Pain Research and Education Center and the Integrated Pain Management Service, both under the direction of Dr. Duncan Lascelles, and Assisi Animal Health, the makers of the Assisi Loop.  to assist with diagnosing pain, physical function and quality of life. The FMPI is the only clinically validated instrument for diagnosing and monitoring feline chronic pain arising from degenerative joint disorders.

The FMPI is easy to use: simply answer the 21 questions, and you will receive a score for your cat. This important tool can be used by cat parents and veterinarians.

In a perfect world, every cat would arrive at the vet appointment with an FMPI filled out online, and then printed out for discussion with the vet. The site can also be accessed right in the vet’s waiting room, via any number of devices, including your laptop, tablet or smartphone. Statistics from completed FMPI’s will be tracked and analyzed at the NCSU College of Veterinary Medicine.

For more information and to complete the FMPI, please visit

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8 Comments on The Feline Grimace Scale: New Tool To Evaluate Pain in Cats

  1. I really appreciate this study and it’s conclusive results. In retrospect, I’ve observed my precious Boots exhibiting the expressions shown in the 3rd photo above (on the right side), especially the squinting of the eyes. I used to administer Buprenorphine (a tiny morsel) in her mouth, which I know is not recommended to do without a Vet’s approval. However, it was apparent that it gave her some relief. Thanks so much for this article!!

  2. Kitties talk to people who will listen and pay attention to them. This is a great article. Nova mentioned this a bit in its episode Cat Tails. Thanks.

  3. I could of used this last week for Tubby. He was in some pain and it was hard to tell except he wasn’t himself. Got him on some meds and it helped.

  4. i dispute the idea that cats ‘hide’ their pain for psych reasons. There’s a orthomolecular reason, namely they don’t show the expected level of pain because ascorbate is a decent pain reliever and they make it in their livers… so what would be painful to us, is sometimes not painful to them, UNTIL they reach their limit on C production…

    and so it’s disappointing that the researchers solution to getting the cats free of pain is to DRUG THEM WITH PAIN MEDS,… Even terminal cancer patients [in the Vale of Leven study] who came into the study dosed with morphine and bedridden, were off the pain meds and up and about with normal activity, once they were on regular IV- C as well as oral…. and stayed that way all the way to the end of the study, even the ones that died of cancer.. and those in the study lived their chosen lives for 5 times longer than the standard terminal cancer patients with their kind of cancer…….. ttyl

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