Construct validity, responsiveness and reliability of the Feline Grimace Scale in kittens

OBJECTIVES

The aim of the present study was to investigate the construct validity, responsiveness and reliability of the Feline Grimace Scale (FGS) in kittens.

METHODS

A total of 36 healthy female kittens (aged 10 weeks to 6 months) were included in a prospective, randomized, blinded study. Video recordings of all kittens were made before and 1 and 2 h after ovariohysterectomy using an opioid-free injectable anesthetic protocol with or without multimodal analgesia. Additional recordings were taken before and 1 h after administration of rescue analgesia (buprenorphine 0.02 mg/kg IM) to painful kittens. Screenshots of facial images were collected from the video recordings for FGS scoring. Four observers blinded to treatment groups and time points scored 111 randomized images twice with a 5-week interval using the FGS. Five action units (AUs) were scored (ear position, orbital tightening, muzzle tension, whiskers position and head position; 0-2 each). Construct validity, responsiveness, and inter- and intra-rater reliability were evaluated using linear models with Benjamini-Hochberg correction, Wilcoxon signed-rank test and single intraclass correlation coefficients (ICCsingle), respectively (P <0.05).

RESULTS

FGS total ratio scores were higher at 1 and 2 h after ovariohysterectomy (median [interquartile range, IQR]: 0.30 [0.20-0.40] and 0.30 [0.20-0.40], respectively) than at baseline (median [IQR]: 0.10 [0.00-0.30]) (P <0.001). FGS total ratio scores were lower after the administration of rescue analgesia (median [IQR] before and after rescue analgesia) 0.40 [0.20-0.50] and 0.20 [0.10-0.38], respectively (P <0.001). Inter-rater ICCsingle was 0.68 for the FGS total ratio scores and 0.35-0.70 for all AUs considered individually. Intra-rater ICCsingle was 0.77-0.91 for the FGS total ratio scores and 0.55-1.00 for all AUs considered individually.

CONCLUSIONS AND RELEVANCE

The FGS is a valid and responsive acute pain-scoring instrument with moderate inter-rater reliability and good to excellent intra-rater reliability in kittens.

An ethogram of acute pain behaviors in cats based on expert consensus

An improved understanding of behaviors reflecting acute pain in cats is a priority for feline welfare. The aim of this study was to create and validate a comprehensive ethogram of acute pain behaviors in cats that can discriminate painful versus non-painful individuals. An inventory of behaviors (ethogram) with their respective descriptors was created based on a literature review of PubMed, Web of Science and CAB Abstracts databases. The ethogram was divided into ten behavior categories that could be evaluated by duration and/or frequency: position in the cage, exploratory behaviors, activity, posture and body position, affective-emotional states, vocalization, playing (with an object), feeding, post-feeding and facial expressions/features. Thirty-six behaviors were analyzed independently by four veterinarians with postgraduate qualifications in feline medicine and/or behavior as (1) not relevant, (2) somewhat relevant, (3) quite relevant or (4) highly relevant and used for content (I-CVI) and face validity. Items with I-CVI scores > 0.67 were included. Twenty-four behaviors were included in the final ethogram. Thirteen items presented full agreement (i.e., I-CVI = 1): positioned in the back of the cage, no attention to surroundings, feigned sleep, grooming, attention to wound, crouched/hunched, abnormal gait, depressed, difficulty grasping food, head shaking, eye squinting, blepharospasm and lowered head position. Seven descriptors were reworded according to expert suggestions. The final ethogram provides a detailed description of acute pain behaviors in cats after content and face validity and can be applied to the characterization of different acute painful conditions in hospitalized cats.

Inter-observer reliability of three feline pain scales used in clinical practice

OBJECTIVES

The present study aimed to evaluate the inter-observer reliability of three feline pain scales commonly used in clinical practice.

METHODS

Twenty cats undergoing elective neutering surgery were assessed both pre- and postoperatively by three independent assessors (a board-certified anaesthetist, a veterinary anaesthesia nurse and a final-year veterinary student) using three different pain 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). Reliability statistics was used to evaluate the level of agreement between assessors.

RESULTS

Twenty-seven groups of paired observations were evaluated, of which 16 (59%) showed fair agreement, eight (30%) showed none to slight agreement and the remaining three (11%) showed moderate agreement based on Cohen's weighted kappa statistics. Based on Cronbach's alpha statistics, 12 (44%) of the 27 groups of observations showed moderate reliability, 12 (44%) showed poor reliability and the remaining three (11%) showed good reliability. No scale was superior to the others in terms of inter-rater reliability (P = 0.179); however, the pair composed of the final-year veterinary student and anaesthesia nurse showed better agreement than the two other pairs of assessors, both of which included the board-certified anaesthetist (P = 0.015).

CONCLUSIONS AND RELEVANCE

Despite the usefulness of behavioural pain scales as clinical tools, their users should bear in mind their limitations, particularly the intrinsic subjectivity and potential variability of outcome between assessors with different backgrounds and level of expertise.

Sex impacts pain behaviour but not emotional reactivity of lambs following ring tail docking

Studies in humans have shown sex differences in response to painful events, however, little is known in relation to sex differences in sheep. Understanding sex differences would enable improved experimental design and interpretation of studies of painful procedures in sheep. To examine sex differences in response to pain, 80 lambs were tested across five cohorts of 16. The lambs were penned in groups containing two male and two female lambs with their respective mothers. Lambs were randomly allocated from within each block to one of four treatment groups; FRing–Female lamb, ring tail docked without analgesia, MRing–Male lamb, ring tail docked without analgesia, FSham–Female lamb, tail manipulated and MSham–Male lamb, tail manipulated. Following treatment, lambs were returned to their pen and were video recorded for 45 mins for behavioural observations of acute pain and posture. An hour after treatment, lambs then underwent an emotional reactivity test that consisted of three phases: Isolation, Novelty and Startle. Following treatment, Ring lambs displayed more abnormal postures (mean = 2.5 ± 0.5) compared to Sham lambs (mean = 0.05 ± 0.4, P = 0.0001). There was an effect of sex on the display of acute pain-related behaviours in lambs that were tail docked (P < 0.001), with female lambs displaying more acute behaviours (mean count = +2.2). This difference in behaviour between sexes was not observed in Sham lambs. There was no effect of sex on display of postures related to pain (P = 0.99). During the Novelty and Startle phase of the emotional reactivity test, Ring lambs tended to (P = 0.084) or did (P = 0.018) show more fear related behaviours, respectively. However, no effect of sex was observed. The results of this study indicate that a pain state may alter the emotional response of lambs to novel objects and potential fearful situations. It was also demonstrated that female lambs display increased sensitivity to the acute pain caused by tail docking compared to males.

Can cat caregivers reliably assess acute pain in cats using the Feline Grimace Scale? A large bilingual global survey

OBJECTIVES

This study aimed to investigate if cat caregivers could reliably assess acute pain using the Feline Grimace Scale (FGS), and if participant demographics could affect scores.

METHODS

An online survey in English and Spanish was advertised by International Cat Care and other platforms (March-May 2021) using convenience sampling. Eligible participants were caregivers >18 years old and non-veterinary health professionals. Participants and a group of eight veterinarians scored 10 images of cats with different levels of pain. Data were analysed using linear models and intraclass correlation coefficient (ICC; α <0.05). Interpretation of the ICC was <0.2 = poor; 0.21-0.4 = reasonable; 0.41-0.60 = moderate; 0.61-0.80 = good; and 0.81-1.0 = very good.

RESULTS

A total of 3039 responses were received with 1262 completed answers from 66 countries (86%, 11.1% and 2.9% identified as female, male or other, respectively). Scores for each action unit (AU; ear position, orbital tightening, muzzle tension, whiskers change and head position) and their sum (FGS score) were not significantly different between caregivers and veterinarians, except for muzzle (caregivers 0.9 ± 0.0; veterinarians 0.7 ± 0.1; P = 0.035). The ICC single (caregivers) was 0.65, 0.69, 0.58, 0.37, 0.38 and 0.65, respectively, for AU ears, eyes, muzzle, whiskers, head and sum of scores. Demographic variables did not affect FGS scores.

CONCLUSIONS AND RELEVANCE

Total FGS scores had good reliability when used by cat caregivers, regardless of demographic variables, showing the potential applicability of the instrument to improve feline pain management and welfare worldwide.

2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats

PRACTICAL RELEVANCE

Increases in cat ownership worldwide mean more cats are requiring veterinary care. Illness, trauma and surgery can result in acute pain, and effective management of pain is required for optimal feline welfare (ie, physical health and mental wellbeing). Validated pain assessment tools are available and pain management plans for the individual patient should incorporate pharmacological and non-pharmacological therapy. Preventive and multimodal analgesia, including local anaesthesia, are important principles of pain management, and the choice of analgesic drugs should take into account the type, severity and duration of pain, presence of comorbidities and avoidance of adverse effects. Nursing care, environmental modifications and cat friendly handling are likewise pivotal to the pain management plan, as is a team approach, involving the cat carer.

CLINICAL CHALLENGES

Pain has traditionally been under-recognised in cats. Pain assessment tools are not widely implemented, and signs of pain in this species may be subtle. The unique challenges of feline metabolism and comorbidities may lead to undertreatment of pain and the development of peripheral and central sensitisation. Lack of availability or experience with various analgesic drugs may compromise effective pain management.

EVIDENCE BASE

These Guidelines have been created by a panel of experts and the International Society of Feline Medicine (ISFM) based on the available literature and the authors' experience. They are aimed at general practitioners to assist in the assessment, prevention and management of acute pain in feline patients, and to provide a practical guide to selection and dosing of effective analgesic agents.

Acute pain responses in dairy calves undergoing cornual nerve blocks with or without topical anesthetic

Dairy calves are routinely administered medicines, vaccines, and anesthesia via injection. Although injections are painful, little is known about methods to alleviate this pain. The aim of this study was to determine whether lidocaine-prilocaine cream, a topical anesthetic, reduced calves' pain response to a subcutaneous injection around the cornual nerve. Calves were assigned 1 of 2 treatments: lidocaine-prilocaine cream at the sites of injection (n = 10) or no cream (n = 9). Thirty minutes after treatment, calves received a subcutaneous injection of 2% buffered lidocaine hydrochloride around the left and right cornual nerves. Contrary to our hypothesis, calves that received anesthetic cream beforehand displayed more escape behaviors during the injections than control calves. Both treatments had similarly low amounts of head-related behaviors afterward. Maximum eye temperature did not differ between the calves that received anesthetic cream and control calves, although eye temperature increased over time for both treatments. Heart rate increased during the 30 s following the first injection in both treatments. There were no treatment differences for any heart rate measures over the 5-min period after the first injection (mean heart rate, root mean square of successive differences, high-frequency power, and the ratio of low-frequency power to high-frequency power). These results suggest that cornual nerve blocks with buffered lidocaine are painful and that a lidocaine-prilocaine cream was not only ineffective in reducing this pain but that it may also worsen it.

[Detection and assessment of acute and chronic pain in Meat Merino ewes using ethological parameters]

OBJECTIVE

The assessment of pain in sheep is a clinical challenge, because being a prey species, they tend to mask it. Since pain in animals cannot be measured directly, various methods are applicable to detect its effects on physiological, biochemical and ethological processes. Clinicians experienced in behavioural assessment are able to reliably determine the level of pain endured by an animal. The objective of this study was to identify behaviours that reflect acute and chronic pain as well as stress in sheep.

METHODS

The behaviour of 36 Meat Merino ewes with contagious footrot (contagious interdigital dermatitis) was analysed during normal activities in the flock and during footrot treatment, which included claw trimming to remove abnormal horn. The behaviour during treatment was compared with that of 12 healthy control sheep of the same breed during routine foot trimming. Grading of the observed behaviours was made using a numerical score. The occurrence of footrot was defined as, and equated with, chronic pain, and treatment was equated with acute pain. For the assessment of stress induced by the manipulative treatment, the data of the healthy sheep were taken as a comparison.

RESULTS

The strongest indications of chronic pain were non-weight bearing lameness of an affected limb, shifting of weight and abnormal gait patterns. Additionally, sheep with footrot urinated more frequently than healthy animals. Stress-related bruxism occurred in healthy and ill sheep during foot trimming, but not during normal activities in the flock. Tail wagging and strong defensive movements of all limbs commonly occurred during footrot treatment. Head shaking appeared to be primarily stress-related in association with dorsal recumbency on the tilt table, but was exacerbated by pain elicited by hoof trimming.

CONCLUSION

The behaviours selected in this study were useful for the identification of chronic and acute pain in sheep; however, correct interpretation of behavioural changes requires an experienced individual.

The neurobiology of acute pain

The mechanisms by which noxious stimuli produce the sensation of pain in animals are complex. Noxious stimuli are transduced at the periphery and transmitted to the CNS, where this information is subject to considerable modulation. Finally, the information is projected to the brain where it is perceived as pain. Additionally, plasticity can develop in the pain pathway and hyperalgesia and allodynia may develop through sensitisation both peripherally and centrally. A large number of different ion channels, receptors, and cell types are involved in pain perception, and it is hoped that through a better understanding of these, new and refined treatments for pain will result.

Effect of band and knife castration of beef calves on welfare indicators of pain at three relevant industry ages: I. Acute pain

Three experiments evaluated the effect of band and knife castration on acute pain for the first 7 d after the procedure on 1-wk-, 2-mo-, and 4-mo-old calves. All calves were blocked by age and weight and randomly assigned to 1 of 3 treatments: sham castration (control, CT), band castration (BA), and knife castration (KN). Experiment 1 evaluated 1-wk-old Angus bull calves ( = 34; 43.0 ± 6.61 kg BW), Exp. 2 evaluated 2-mo-old Angus bull calves ( = 34; 91.5 ± 11.93 kg BW), and Exp. 3 evaluated 4-mo-old Angus bull calves ( = 35; 157.6 ± 22.52 kg BW). For all experiments, physiological and behavioral parameters were collected before (d -1 and immediately before castration [T0]) and after (60 and 120 min and on d 7) castration to assess acute pain. Physiological measures included complete blood cell count, cortisol, substance P, and scrotal temperature. Behavioral measures consisted of a visual analog scale, stride length, and time and frequency budgets for walking, standing, lying, tail flicking, foot stamping, and head turning. Performance parameters included initial and final BW and ADG. In Exp. 1, tail flicking was greater ( = 0.02) in KN calves compared to BA calves 2 to 4 h after castration, although no differences were seen between BA and KN compared to CT calves. In Exp. 2, a treatment × time interaction ( = 0.02) was observed for cortisol, where KN calves had greater cortisol concentrations 120 min after castration compared to BA and CT calves; KN calves also lay down and ate less ( < 0.01; = 0.02) and stood and walked more ( < 0.01; = 0.05) compared to BA and CT calves 2 to 4 h after castration. In Exp. 3, a treatment × time interaction ( < 0.01) was observed for cortisol concentrations in which all treatments were different from one another at 60 and 120 min, with BA calves having the greatest concentrations, KN calves being intermediate, and CT having the lowest concentrations. Overall, KN and BA castrated calves presented physiological and behavioral changes associated with acute pain; however, 2-mo-old BA calves presented the fewest behavioral changes and no physiological changes associated with acute pain compared to CT calves.