Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

The Feline Grimace Scale: How it Works & FAQ (Vet Approved)

man petting a sick siberian cat

Cats are masters at hiding it when they’re not feeling well or in pain, which can make it difficult for pet parents to know when something is wrong. Veterinarians first look for signs such as changes in behavior to determine if cats are in pain.

Feline facial expressions can also be incredibly informative. The Feline Grimace Scale (FGS) is a tool veterinarians use to tell if cats are in acute pain and, if so, how intense it is and if pain management may be appropriate.

divider 2 cats

How Does It Work?

Cats must be observed for about 30 seconds to obtain accurate scores, and they should be evaluated when they’re not eating, sleeping, or grooming themselves. Ear, whisker, head position, muzzle tension, and orbital tightening are called “action units,” and each is given a score ranging from 0 to 2; higher scores indicate more intense pain.

Cats with their ears facing forward, for instance, receive scores of 0 for that action unit, while those with ears that are flattened and pointing sideways get higher scores. Scores are provided for each action unit and added together to come up with a final total. Scores higher than about 4 indicate that pain management is required.

There’s a handy fact sheet with pictures and descriptions of what to look for at each action unit that pet parents can use to evaluate their companions’ pain. There’s also an app that makes it easy for pet parents to work with the tool.

Shocked cat looking close up
Image Credit: Pandora Pictures, Shutterstock

How Was the FGS Developed?

Researchers at the Université de Montréal developed the scale by comparing the facial features of cats in pain with those of a control group.1 Cats brought into the university’s teaching hospital for emergency treatment were observed and evaluated to determine if they were in pain.

Those who were in pain were filmed before receiving any medication. Video recordings of healthy control cats were also made. Still photos were made of the cats’ faces and scorers used the images to identify how the faces of cats in pain and those who aren’t differ. The features identified as different were used to create the FGS — they’re the scale’s action units.

Where Is It Used?

The FGS is used by veterinarians in clinical settings to determine if cats are in pain, such as after surgeries or dental procedures, or when evaluating pets suffering from conditions like urinary blockages and pancreatitis.

Behavioral changes can indicate that cats aren’t feeling well, but the FGS can tell veterinarians how much acute pain cats are experiencing so it can be addressed with medication when warranted. Pet parents can also use the tool to get an idea of if their companions are in severe pain or not.

red tabby cat in pain walking on grass outdoor
Image Credit: lagunabluemolly, Pixabay

Can Pet Parents Use the Tool?

Yes. Scholars ran a study in which veterinarians and cat owners were asked to look at pictures of cats and score their pain levels using the FGS. The scores given by the two groups were largely the same (although there were some differences), leading researchers to conclude that the scale can reliably be used by pet parents.

The cat owners who participated in the study were able to work with the tool effectively without any special training. The FGS website has a section where pet parents can practice their skills.

The tool is designed to evaluate acute pain, so it’s not appropriate for understanding how cats with chronic conditions are feeling. Still, it can help pet parents get an idea of the level of pain their cats may be experiencing due to surgery, wounds, urinary obstructions, and constipation.

divider 2 cats

Frequently Asked Questions (FAQ)

Are There Grimace Scales for Other Animals?

Yes! Grimace scales have been developed to evaluate pain levels in mice, rats, rabbits, sheep, ferrets, and horses.

Why Do Cats Hide Signs of Pain?

Cats really haven’t been domesticated for that long, and they still have many of the behavioral traits that served their wild ancestors well, such as a tendency to hide signs of illness.

Cats in the wild are both predators and prey, and predators target animals who are easy to catch, such as those who are hurt or ill. Hiding signs of an illness is an evolutionarily sound strategy that contributes to cats’ ability to survive in the wild.

domestic striped kitten with a sad face feels sick
Image Credit: Julia Cherk, Shutterstock

How Do Veterinarians Treat Feline Pain?

Veterinarians sometimes rely on medications to help relieve feline pain, but there are other options, including physical therapy, acupuncture, and massage. Dietary supplements are also occasionally recommended. Human pain medication should never be given to cats, and pets who aren’t feeling well or appear to be in pain should be seen by a veterinarian immediately.

If you are concerned about the health and well-being of your pet, seek veterinary advice for the best course of action.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content for PangoVet2 save money

divider 2 cats

Conclusion

The FGS was developed by researchers at the Université de Montréal to help veterinarians evaluate acute pain levels in cats. Cats’ ears, whiskers, head positions, orbital tightening, and muzzle tension are all scored when using the FGS; higher numbers indicate more serious pain.

Veterinarians use the scale to identify whether cats need pain medication after surgical and dental procedures, and it can help pet parents determine if their companion is in serious distress and needs veterinary assistance.


Featured Image Credit: Olesya Alexandrova, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Why Do Cats Like Fish? 4 Interesting Vet-Reviewed Reasons

There are few things more ingrained in our thoughts and beliefs about domestic cats than the connection of cats liking fish. It is...

10 Famous TikTok Cats: Iconic Cat Influencers in 2025

The internet loves cats, so it’s no surprise that some cats have risen to fame and become influencers on social media. Cats are...

How Many Cats Can You Own in Ohio? What Law States

There are typically laws or ordinances in place in certain areas that restrict the number of pets a household can own. As an...

Tooth Resorption in Cats: Signs, Causes & Treatment (Vet Answer)

Everyone who has owned a cat has had the dreaded dental disease conversation with their vet. And it should be no surprise to...

More related

Is Your Cat Sleeping Too Much or Not Enough? Vet-Reviewed Signs & When to Worry

A quick glance in my bedroom on a sunny day will likely reveal my three male cats sprawled on the bed. If I...

7 Best Scratching Posts for Large Cats in 2025 – Reviews & Top Picks

Dogs must bark, birds must fly, and cats must scratch. While you adore your kitty for their cuddly demeanor, playful nature, and angelic...

Why Is My Sick Cat Hovering Over Their Water Bowl? (Vet Answer)

A cat’s water intake depends on a number of factors, including their diet, age, and activity levels. However, what if you’ve noticed your...

How to Use Cat Nail Clippers: 4 Vet-Approved Steps

Devoted cat parents go above and beyond to create comfortable environments for their felines and ensure their furry friends are always well-fed and...

Keep reading

Cat Love Bites: What They Mean & Why They Happen

Almost every cat owner has experienced playtime gone wrong. One minute, you’re petting your cat’s fuzzy head, and the next, they’re biting your fingers. Well, assuming that your cat isn’t drawing blood with the bites, it is safe to assume...

A,Young,Tabby,Cat,Bites,A,Woman's,Feet.,Cute,Kitten

How to Introduce a Cat to a New Litter Box (7 Vet-Approved Tips)

There are several possible reasons you might need to switch up your cat’s litter box. Perhaps they have outgrown their present one, are having difficulties getting in and out, or need something more open or enclosed. Simple enough, right? Not...

sphynx cat using purple cat litter box

Are Rubber Plants Toxic to Cats? Vet-Reviewed Houseplants Examined  

The American rubber plant (Peperomia obtusifolia) is native to South America. However, it will flourish indoors with proper humidity and adequate sunlight. This plant is also called a baby rubber plant and a pepper face plant. Your cat may take...

Catster_Are Rubber Plants Toxic to Cats

Can Cats Eat Dragonflies? Vet Approved Facts & FAQ

Cats love to chase things, especially things that fly quickly. It is one reason why so many birds die due to domestic cats every year (which can actually become a serious problem in some areas). Dragonflies are another animal that...

Can Cats Eat Dragonflies

Weruva Patés Cat Food Review (2025 Update)

Review Summary You may be familiar with Weruva, as it’s a brand that’s been around since 2006, but you might not be as familiar with all their food lines. One of their lines is the patés line, featuring patés high...

Weruva Classic Cat Paté Review

Can Cats Eat Corned Beef? Vet Approved Risks & Nutritional Information

Cold corned beef and boiled cabbage may be a St. Patrick’s Day staple for many Americans, but unfortunately, this dish is another human food that your cat needs to skip. While cats can and should eat meat, the high salt...

Can Cats Eat Corned Beef

Can Cats Be Allergic to Dogs? Vet-Approved Facts & FAQ

Cats can be allergic to certain food ingredients, flea saliva, dust mites, molds, and even outdoor particles like pollen from trees, grass, and weeds. Itchy skin, gastrointestinal problems, and even difficulty breathing can all be caused by allergies. If you...

Jack russell terrier dog and irritated white cat on the bed

Why Is My Cat Over-Grooming? 5 Vet-Reviewed Reasons

It’s completely natural and healthy for cats to groom themselves and each other, but if your cat starts overgrooming, there may be a medical issue that needs addressing or environmental changes to consider. Signs of overgrooming include excessively licking the...

cat licking paws