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The Feline Grimace Scale: A New Tool To Evaluate Pain in Cats

Written by: Ingrid King

Last Updated on February 7, 2024 by Catster Editorial Team

man petting a sick siberian cat

The Feline Grimace Scale: A New Tool To Evaluate Pain in Cats

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.

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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.

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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

Featured Image Credit: Olesya Alexandrova,Shutterstock

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