Can you help with the Feline Grimace Scale research?


Editor's Picks
15 February 2021
Scientists have developed a way to tell if your cat is in pain just by reading their facial expression — and now they need your help with it. Researchers Beatriz Monteiro and Paulo Steagall explain all.

Image: Example of a cat without pain (right) and a cat with severe pain (left).

Note on the pain-free cat: the ears are erect and facing forward, the eyes are wide open, the muzzle has a round shape, the whiskers are loose and relaxed, and the head is higher than an imaginary line crossing the shoulders.

Note on the cat in pain: the ears are low and rotated backwards, the eyes are squinted, the muzzle has an elliptical shape, the whiskers are tense and clumped together, and the head is about the same height as the shoulders.

Beatriz Monteiro and Paulo Steagall, along with colleagues from the University of Montreal, have developed a way of recognising if our cats are in pain just by looking at their faces. Here, Beatriz and Paulo explain how this works and ask if you can help develop this incredible tool — it could benefit cats all over the world…

Cats are brilliant at hiding illness or pain. So, if you could look at your cat and recognise they were in pain, would you be interested in doing so? Being able to would allow owners to seek veterinary care and catch health issues sooner, which could mean cats suffer less, treatment could be more successful, and it could cost owners less too.


Along with colleagues from the University of Montreal, we have developed what is called the Feline Grimace Scale — a tool developed for the assessment of pain in cats based on changes in facial expressions.

The Scale works by observing a cat for 30 seconds and looking at their facial features: how open the eyes are, how the ears are positioned, how tense the muzzle is, how curved and tense the whiskers are, and how the head is held above or below the shoulders. Each action is assessed and an overall score given to indicate the level of pain the cat is in. You can find out more about the tool by visiting

Following development, the tool underwent several steps of scientific validation to ensure that it measures what it is intended to measure (in this case pain), that it is repeatable by different evaluators and over time, and that it can discriminate between different conditions. It was found that it works on cats with different medical and surgical conditions, and that it can be used both by looking at the cat itself or at a picture of the cat.

The Feline Grimace Scale has been found to be a valid, fast, reliable and easy-to-use tool that helps with pain assessment, which could be revolutionary in helping our cats.

Content continues after advertisements


We think of pain in two different ways: chronic and acute. Chronic pain refers to long-term conditions, such as osteoarthritis. Acute pain is shorter-term pain and, for example, includes pain after surgery, trauma, constipation, obstruction causing an inability to pass urine, and cystitis. The Feline Grimace Scale is used in the assessment and recognition of acute — not chronic — pain. However, pain is a very dynamic process and acute pain episodes can also occur in conditions which usually cause chronic pain.

Cats with acute pain may show changes in their facial expression for several minutes to several hours, depending on the cause of pain. Changes in facial expressions related to pain do not happen just for a split second. For example, if your cat is resting on the couch, half sleeping, and hears a noise in the background, it might have a facial expression which is similar to that of pain (the ears are low, the eyes are half closed, and the head is down) for a few seconds. However, a few moments later, the ears should return to their normal position. This means that evaluation of pain in cats should not be done if the cat is sleeping, eating, grooming, or performing another activity. We must wait until the cat has stopped these activities to evaluate their facial expressions. Facial changes related to pain will persist for more than just a few seconds.


Pain in cats has been neglected over the years, probably because our feline friends hide it so well. The veterinary world recognises that cats receive less pain relief for problems in comparison to dogs. The Feline Grimace Scale was developed to help vets to recognise and treat pain in cats better. For example, based on the scores of the Feline Grimace Scale, the vet knows if the cat is in pain, if pain killers are needed, and if pain decreases after treatment.

Working with final year veterinary student Netta Lee from the University of Edinburgh and in collaboration with International Cat Care, the next step is trying to find out whether cat owners, without any veterinary training, are able to detect acute pain in cats by using the Feline Grimace Scale, and we would like readers of Your Cat Magazine to help.


Until this year, all the studies on The Feline Grimace Scale had been performed using scores from vets. More recently, a small study showed that cat owners too can reliably use the Feline Grimace Scale. On two different occasions, a few cat owners scored images of cats with different degrees of pain. Their scores were similar to those from vets and they were able to repeat these scores one week later. What the researchers would like to know is whether these findings would be the same if lots of cat owners across the world undertook the same test.

So, as a cat owner, you are officially invited to contribute to a follow-up research study aiming to investigate cat owners’ ability to assess acute pain in cats using the Feline Grimace Scale. Cat owners and breeders are invited to complete an online survey available from March 15 — May 15, 2021 using the following link:


Your participation is entirely voluntary and anonymous. Anyone older than 16 years old who owns or has previously owned a cat, and who does not have veterinary training (vet or nurse) can participate. The survey takes approximately 20 — 25 minutes to complete and includes 10 images of cat faces with different degrees of pain. You will be asked to read a short training manual and to score these images using the Feline Grimace Scale — you can still look at the manual, so it is not a test of memory!

It looks at different aspects of the head and face (called action units) which are: ear position, orbital tightening (the shape of the area around the eye), muzzle tension (the area around the nose), whisker position, and the position of the head in relation to the cat’s shoulders. Participants will not be identified but can choose to respond to a few demographic questions at the end of the survey which will be available in English and Spanish languages. This will allow researchers to understand the effects of different ages, sex, backgrounds, household settings, and geographical locations on the Feline Grimace Scale scores.

Results from this study could represent a major contribution in our understanding of feline pain. The Feline Grimace Scale could be the first instrument for feline acute pain assessment that could be used by cat owners at home — this would be a great advance for feline medicine.


or for more information, visit

Content continues after advertisement