New scale interprets pain from feline facial expressions

Published on September 11, 2019

Assessing pain in cats is difficult, but a new scoring system that interprets changes in facial expression could help provide practitioners with clinical guidance.

Dr. Paulo Steagall, an associate professor of veterinary anesthesia and analgesia at the University of Montreal, presented the Feline Grimace Scale for the first time in the United States during a session in August at AVMA Convention 2019 in Washington, D.C. He said details about the FGS will be published in Scientific Reports, a journal from Nature Research.

Researchers at the University of Montreal, including doctoral student Dr. Marina Evangelista, categorized and tested five facial action units indicative of pain in cats: ear position, orbital tightening, muzzle tension, whisker position, and head position. A score of 0 means absence of the 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 and needs rescue analgesia. The maximum total score is 10.

Feline Grimace Scale
Images of cats in which pain was absent, moderately present, or markedly present (Courtesy of Dr. Paulo Steagall)

The scoring of 0, 1, or 2, respectively, for each facial action unit is as follows:

  • 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.

Dr. Steagall led session attendees through scoring exercises. Among the examples were the following:

  • Maman, a 1-year-old female cat spayed a week earlier at a shelter, was admitted with inappetence and fever. A post-operative infection and infection with feline immunodeficiency virus were suspected. Before rescue analgesia, she received the maximum FGS score of 10. Afterward, the score decreased to 3.
  • Suzy Petit, a 7-year-old female cat, was admitted because of vomiting. A foreign body was suspected. Her score was 6 before rescue analgesia and 3 afterward.
  • Pacane, a 1-year-old female cat with pancreatitis, received a score of 4 before rescue analgesia and a score of 0 afterward.

Dr. Steagall said researchers at the University of Montreal are conducting a series of studies validating the use of the FGS specifically for cats with orofacial pain, such as after tooth extraction procedures.