Introduction

Appropriate pain assessment is required for proper treatment of pain. Pain evaluation should be part of the initial physical examination of all patients (TPR: temperature, pulse, respiration). Physiological changes such as heart and respiratory rates, pupil size, and neuroendocrine essays are not correlated with acute pain in cats. Anxiety, stress and fear will affect these variables particularly in the hospital setting. Appetite and blood pressure are the only physiological “markers” that have been correlated with increased pain, but blood pressure monitoring is not practical in a busy clinical practice and the cat may not eat simply because it is not hungry. Therefore, pain evaluation is mostly performed using subjective behavioral changes.

Pain Behaviours/Postures

Key behavioral indicators of abdominal pain in cats have been identified and include abnormal postures such as hunched-up guarding or splinting of abdomen.¹ An expert consensus using the Delphi-method has identified 23 items that are considered as certainly or often sufficient to establish the occurrence of pain.² Some of these behaviors are commonly observed in acute pain and include, for example, reaction to palpation, withdraw/hiding, decreased appetite, hunched-up posture, lower head posture, growling, groaning and eyes closed. Indeed, some of these signs/behaviors were already identified in the previous literature when using validated pain scoring systems.^1,3 However, some of these changes may be only related to the cat’s temperament and show how important the context/environment is when evaluating pain in cats. For example, the type and duration of surgery, severity of pain, hospitalization, individual variability, age and disease should all be considered in the assessment of pain.

Feline Pain Scoring Instruments/Tools

A systematic review investigated different pain scales in regard to validity (construct, criterion and content), reliability (internal consistency, intra-rater and inter-rater and test-retest) and sensibility (identification of a cut-off point and responsiveness) in cats.⁴ The UNESP-Botucatu multidimensional composite pain scale (MCPS) was the only one evaluated for the three above components.

The visual analog scale, the numerical rating scale and other descriptive rating scales did not present any kind of validation and should not be used for the evaluation of pain in cats. The MCPS refers to sensory and affective domains of pain; it was originally developed in Brazilian Portuguese and translated, and further validated, in English, Spanish, French and Italian languages.^3,5,6 These articles are free for download. The MCPS is a valid, reliable and responsive instrument that involves different domains such as ‘pain expression’ and ‘psychomotor change’. On the other hand, this scale has only been validated for evaluating cats after ovariohysterectomy and is time-consuming. It is not known whether this tool is suitable or would have the same “performance” in cats undergoing other types of surgical procedure, trauma, or with medical, neuropathic pain. Currently, a short form of the scale is under investigation and may circumvent some of the above issues. The Glasgow rCMPS-Feline has been shown to be valid with some evidence of responsiveness; nevertheless, reliability testing has not been reported. Construct and content validity were reported.⁷ The instrument is easy to use and theoretically, it can be applied to any kind of acute pain (medical, surgical, etc.). An updated version (Glasgow CMPS-Feline) has been recently published and includes facial expressions with a cut-off for interventional analgesia of ≥5/20.8 This latter version should be preferred as it showed increased discriminatory ability when compared with the previous version.⁸

Feline Grimace Scale (FGS)

Facial expressions have been used to evaluate pain in different species. Recently, the development of the Feline Grimace Scale revealed differences between painful and non-painful cats.⁹ Five action units have been identified and include ear position, orbital tightening, muzzle tension, and whiskers and head position. The Feline Grimace Scale is an interesting addition to feline acute pain assessment. At the time of writing, the manuscript reporting the scale was under review and will report the full validation of the instrument using image assessment. A review on acute pain assessment has been recently published.¹⁰ This lecture presents a quick overview of the MCPS, CMPS-F and FGS. It presents a series of videos of cats before or after surgery where the audience has the chance to practice the use of these scales.

References

1.  Waran N, Best L, Williams V, et al. A preliminary study of behaviour-based indicators of pain in cats. Anim Welf. 2007;16:105–108.

2.  Merola I, Mills DS. Behavioural signs of pain in cats: an expert consensus. PloS One. 2016;11(2):e0150040.

3.  Brondani JT, Mama KR, Luna SP, et al. Validation of the English version of the UNE-SP-Botucatu multidimensional composite pain scale for assessing postoperative pain in cats. BMC Vet Res. 2013;9:143.

4.  Merola I, Mills DS. Systematic review of the behavioral assessment of pain in cats. J Fel Med Surg. 2016;18:60–76.

5.  Brondani JT, Luna SPL, Crosignani N, et al. Validez y confiabilidad de la versión en español de la escala multidimensional de la UNESP-Botucatu para evaluar el dolor postoperatorio en gatos. Arch Med Vet. 2014;46:477–486.