The Feline Grimace Scale, developed by researchers at the University of Montreal, has gained wide acceptance and use among veterinarians to determine the pain level a cat may be experiencing.
The accurate assessment and management of pain is essential in ensuring the best quality of life for animals. The recognition and evaluation of pain remains a major limiting factor in pain management for pets. There is good evidence that facial expression can be a useful, valid, and reliable tool for recognizing and evaluating pain in humans and other animals. Both the sensory and emotional components of pain have been demonstrated to affect facial expression. Many of the mammalian species studied to date have similar facial expression responses to pain.
The researchers categorized, tested, and scored five facial action units indicative of 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 relaxed 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
A score of 0 means the absence of the facial action unit, 1 is moderate appearance or uncertainty, and 2 is obvious appearance. A total score of 4 or more means the cat is in pain. The maximum total score is 10.
The cat with no pain has ears standing up, eyes round and wide open, a rounded muzzle, relaxed whiskers, and head above the shoulders.
A cat experiencing some pain will have eyes squinted, ears more to the side, less curvature in the whiskers, a less-rounded muzzle, and head at the shoulder level.
Cats with more severe pain will have eyes squinted or shut, ears flat to the sides, straight or upwardly curved whiskers, more tension in the muzzle, and head below the shoulders.
Once it is determined the cat is experiencing pain, the next step is to determine the cause. Arthritis, urinary infection or blockage, dehydration from kidney disease, gastrointestinal upset, and wounds are some of the possibilities. If you suspect your cat is showing signs of pain, a trip to your veterinarian for a full examination, bloodwork, and radiographs should be arranged.