What Is the Cat Grimace Scale?

The Cat Grimace Scale, also called the Feline Grimace Scale, is a structured observation method that helps owners and veterinary professionals look for facial changes associated with acute pain in cats.

Where the scale comes from

The Feline Grimace Scale was developed from research into the facial expressions of cats experiencing acute pain. The original development and validation study was published in 2019 in Scientific Reports (Evangelista et al.). Researchers identified five facial action units that tend to change together when a cat is uncomfortable: ear position, orbital tightening, muzzle tension, whisker position, and head position. Instead of asking a person to judge whether a cat simply looks painful, the scale asks for a separate 0, 1, or 2 score for each of those five areas.

The approach is based on the same idea used in human and animal pain assessment: breaking a complex judgement into smaller, repeatable observations makes the result more consistent between different people and between different moments. For owners at home, that structure is useful because it provides a checklist rather than a vague feeling that something is wrong.

Why cats need a different kind of observation

Cats are prey animals as well as predators, and they often hide signs of weakness. A cat that is painful may not limp, cry, or stop eating right away. The changes are more likely to appear in small details: ears held slightly lower, eyes narrowed a little, a muzzle that looks more drawn than usual, or whiskers that point forward instead of curving to the sides. Individually, each change can be explained away. Together, they form a pattern worth noticing.

This is why the scale emphasises facial features rather than obvious behaviour. Behaviour can be useful too, but it is shaped by the environment. A frightened cat and a painful cat may both hide, while a confident cat may still interact normally despite discomfort. Facial action units give observers a more direct, standardised view of one part of the picture.

The five facial action units

• Ear position — whether the ears are forward, slightly rotated outward, or flattened.
• Orbital tightening — how open or narrowed the eyes appear.
• Muzzle tension — whether the muzzle looks relaxed and rounded or tense and drawn.
• Whisker position — whether the whiskers curve to the sides or straighten and point forward.
• Head position — whether the head is held above, level with, or below the shoulder line.

Each action unit is scored on its own, and the five values are added together to make a total from 0 to 10. You can read more about each feature on the cat facial expressions guide.

What the scale is used for

In veterinary settings, the scale can support pain assessment after surgery or during treatment. For owners at home, the value is slightly different: it gives a calmer way to look at a cat's face before deciding whether to seek advice. An owner can photograph the cat, compare the photo with reference images for each feature, and produce a score without needing to interpret medical terminology.

The tool on this site walks through that process one feature at a time. It keeps the photo in the browser, offers a skip option when a feature is not visible, and explains the result at the end. You can start a Cat Grimace Scale assessment here.

What the Cat Grimace Scale is not

The scale is not a diagnostic test. It does not measure pain directly, it cannot identify arthritis, dental disease, or any other condition, and it should not be used to decide whether a cat needs medication. A score is an observation of the face at one moment, made from a photograph, and it is affected by stress, sleep, lighting, and camera angle.

A low score does not guarantee that a cat is comfortable, and a high score does not prove that a cat has a serious illness. The scale works best as a prompt: it helps an owner look more carefully and, when needed, describe what they saw when they speak to a veterinarian.

How the score is structured

Each feature is scored as absent, moderately present, or markedly present. Those three states are recorded as 0, 1, and 2. A total of 0 means no facial signs were scored, while a total of 10 means all five features were scored as markedly present. Published owner guidance commonly uses a total of 4 or higher as a prompt to contact a veterinarian, although the threshold is guidance rather than a diagnosis. For a more detailed explanation, see how to read a Cat Grimace Scale score.

Limitations to keep in mind

Photographs flatten a three-dimensional face, hide movement, and depend heavily on angle and light. A photo taken from above can make the eyes look narrowed, while a dark image can hide the muzzle outline. Cats also differ from one another: some naturally have flatter faces, larger eyes, or whiskers that sit forward. The most reliable result comes from comparing a cat with itself over time, in the same setting, rather than comparing one cat with an ideal average.

For a fuller picture of how the five features behave and how they interact, read the guide to how the scale works or explore other signs a cat may be in pain.

Sources and further reading

• Feline Grimace Scale official website — felinegrimacescale.com
• Evangelista MC, et al. Facial expressions of pain in cats: the development and validation of a Feline Grimace Scale. Scientific Reports. 2019. DOI 10.1038/s41598-019-55693-8