The assessment of pain in cats is an area of increasing interest in the veterinary profession. Many scales and systems to assess pain have been developed, however, they have not been directly compared. Three widely used scales; the Glasgow Feline Composite Measure Pain Scale (CMPS–Feline), the Colorado State University Feline Acute Pain Scale (CSU – FAPS), and the Feline Grimace Scale (FGS) are considered user-friendly and reliable in clinical settings.

The CMPS–Feline has been validated for post-surgical pain and various pain syndromes, and some reports suggest that users may obtain reliable results even without extensive training. The FGS was initially validated for abdominal pain but is applicable to acute pain from various conditions. The CSU – FAPS is undergoing initial validation with promising results, and is notable for its ease of use, potentially making it faster to apply in clinical settings. Recent research supports the reliability of these scales and indicates their usability by people with diverse backgrounds and training.

Despite their clinical utility, one limitation of behavior-based pain scales is their subjectivity, which can be influenced by the assessor’s expertise in pain assessment and feline medicine in general. This study aimed to evaluate the inter-observer reliability of the three above-described commonly used feline pain scales. The authors hypothesized that these scales would show fair to moderate agreement between assessors with different backgrounds and expertise levels.

The study involved client-owned cats undergoing routine neutering surgery at two veterinary teaching hospitals. Three assessors were included: a board-certified veterinary anesthetist, a veterinary anesthesia technician, and a final-year veterinary student. These individuals independently assessed the cats using the three pain scales both preoperatively and postoperatively. The assessors were blinded to each other’s scores.

Statistical analysis included a sample size calculation based on the hypothesis of fair to moderate pairwise agreement between independent assessors. The Cohen’s weighted kappa test and Cronbach’s α method were used to assess reliability, with inter-class correlation coefficient values indicating reliability levels. The study classified inter-rater agreement and inter-class reliability into categories ranging from none to almost perfect based on standard systemology.

The results showed that inter-observer reliability varied from poor to fair/moderate, indicating substantial subjectivity in these pain assessment tools. The levels of agreement differed between pairs of assessors, with the veterinary anesthesia technician and final-year veterinary student exhibiting better agreement than the pairings that included the board-certified anesthetist. While the authors of this study recognize the clinical utility of these scales in assessing perioperative pain in cats, it underscores the need for users to consider potential variations in outcomes based on the assessor and their interpretation of scale application. The findings caution against over-reliance on these scales as objective measures of pain in cats, highlighting the inherent subjectivity in their application.  ~MRK