Rabbits are the third most popular companion animal, with an estimated 0.9 million in the UK (PDSA, 2019). Despite this, 30% of rabbits were not registered with a veterinary practice (PDSA, 2019).
The ability to measure pain is an important duty and incorporated within the RCVS code of conduct for the registered veterinary nurse (RVN) to identify if there is a need for analgesia or further nursing interventions (Malik and Leach 2017). However, rabbits, as a prey species, can mask symptoms as a survival mechanism to avoid appearing weak (Rendle and Hubbard, 2017). Consequently, pain can go undetected, affecting health and welfare. In addition, some RVNs may be apprehensive about providing suitable rabbit care because of inexperience of nursing this species (Foote, 2018).
It is important in order to standardise the use of pain scales, that the evaluation of pain is consistent between different observers and that it is both repeatable and an objective measure of pain response by the animal when managing and assessing an individual's pain level (Robinson, 2016). The RVN is in an ideal position to address rabbit discomfort as they regularly interact with patients while delivering nursing care (Goldberg, 2017). However, some nurses may not regularly interact with rabbits compared with canine and feline patients. The Rabbit Grimace Scale (RbtGS) (Rabbit Grimace Scale, Pain and Animal Welfare Sciences Group, n.d.) is a behaviour-based pain score system designed for rabbits, which can help interpret signs of acute pain through subtle changes in their facial expressions (Mancinelli, 2015). Although the RbtGS is a validated method for pain assessment in rabbits, it is often underutilised in practice (Mancinelli and Bament, 2014), and this could suggest that there may be barriers to the RbtGS design and viability in facilitating pain recognition (Flecknell, 2018).
Literature review
Rabbits constantly scan their environment, and at the first sign of danger, will attempt to flee (Varga, 2016). If this is not possible, the rabbit will hide, become silent, and mask signs of illness as a survival mechanism to avoid attracting the attention of predators (Varga, 2016; Green, 2018).
Pain
For RVNs to assess pain, there needs to be an understanding of the rabbit's physiology. The effect of pain on the rabbit's physiology is described by Richardson (2016), who states that pain can be categorised as either acute; sudden onset, with limited duration; or chronic, generally long term and of longer duration.
Varga (2016) describes the pathophysiology of pain, which is caused when a noxious stimulus damages normal tissues. The damaged cells release chemicals that stimulate the nociceptive receptors at the nerve endings, which send an action potential via the spinal cord to the brain that allows the sensation of pain to occur (Varga, 2016). However, in many prey species a lack of pain awareness and response, because of the descending control pathways, which suppress pain neuronal activity to limit pain perception, is vital to allow a flight response (Varga, 2016).
Stress
Rabbits are susceptible to stress when placed in unfamiliar situations and surroundings, such as a veterinary practice (Speight, 2018). When rabbits are exposed to a stressful event, an endocrine response occurs that releases cortisol, which stimulates the sympathetic nervous system, and prepares the body for ‘flight’ (Varga, 2016; Green, 2018).
Pain and stress are linked, as pain can cause stress (Richardson, 2016). Goldberg (2017) recognised that although some animals exposed to stress may successfully adapt, others may become distressed. Such behaviours can lead to further ailments that can be fatal, such as ileus (Ager, 2017).
The role of the veterinary nurse
The RVN plays an important role as an advocate for pain management (Sibbald, 2018). Goldberg (2017) agreed, stating that although this can be daunting with exotic species, the RVN is in a unique position as they continually interact with patients when delivering nursing care, and therefore their observations must be effectively communicated to the veterinary surgeon (VS). In doing so, Richmond (2016) highlights that an RVN can contribute to the implementation of an appropriate analgesic protocol and apply nursing interventions. However, for pain in rabbits to be adequately managed, the RVN needs to be able to recognise and assess it correctly.
Rabbit Grimace Scale
To aid in the identification of pain and stress in rabbits, a pain score system known as the Rabbit Grimace Scale (RbtGS) was developed for animals within a laboratory setting, which can be used alongside physical parameters to support the diagnosis of pain (Keating et al, 2012). The RbtGS assesses five areas (orbital tightening, cheek flattening, nostril shape, whisker change and position, ear shape and position) whereby the individual can be scored 0 no presence, 1 moderately present or 2 obviously present. Therefore, when adding these scores together a rabbit could score between 0, no detectable pain up to 10 severe pain. Any score over five indicates the animal is experiencing pain (Varga, 2016). McBride (2017) and Green (2018) recommended the use of the RbtGS in determining if a rabbit is in pain by assessing their facial expressions. The RbtGS also allows repeated assessments that remain consistent between observers, which can be used to evaluate a rabbit's response to treatment (Robinson, 2016).
The benefits of the RbtGS were highlighted by Keating et al (2012), who developed the RbtGS while undertaking a study that evaluated the efficacy of EMLA cream as a topical analgesic for ear tattoos in rabbits. The changes in facial expression aided the development of the RbtGS, which the authors found to be a reliable and accurate method of assessing acute pain. However, Richardson (2016), stated that the RbtGS may not be practical in a busy veterinary environment. Sibbald (2018) discussed further limitations of the RbtGS, and recognised that some important markers of pain in rabbits are not incorporated into the RbtGS, including abnormal behaviours, teeth grinding, and hunched posture, which should be considered.
Veterinary practice over time has witnessed an increase in rabbit patients, and the need to help identify pain in rabbits is at the forefront of welfare concern and professional responsibility of both the veterinary surgeons (VS) and RVN. As the RbtGS is now a validated pain score system for rabbits, it begs the question: why is it still underutilised in practice and is it a useful construct that can increase rabbit welfare?
Methodology
The participants at the University Centre Askham Bryan were either student veterinary nurses (SVNs) at level 4 or level 5 FdSc Veterinary Nursing or RVNs enrolled on the level 6 Veterinary Nursing BSc top up degree. In total there were 31 participants, 16 level 4 SVNs, nine level 5 SVNs, and six level 6 RVNs.
The rabbit subjects were recruited from veterinary practice or the university centre, and could be of any breed, sex, life stage, healthy or experiencing a pre-existing illness or health condition. Health status was mixed in both environments. 19 rabbits were video recorded. All rabbits were fully conscious during video footage and each video was a continuous recording of 1 minute on a consultation table, with an additional person such as a VS, owner or veterinary nurse assisting to ensure the rabbit's safety. Out of the 13 rabbits recorded in the veterinary practice, seven were assessed to be in pain or stressed, and four were healthy. Out of the six rabbits recorded at the university centre, one rabbit was assessed to be in pain or stressed and the remaining five were healthy. As a blind study, only the researcher's and supervisor were aware of the rabbit's health status as assessed by a VS prior to video footage.
A colour copy of the RbtGS and manual was given to all participants (https://www.nc3rs.org.uk/rabbit-grimace-scale). Any score over 5 on the RbtGS indicates that the participant considered the rabbit to be in pain.
To compare the effect of video and observations, the level 6 RVN group were asked to undertake live observations of six rabbits within University Centre. The RVNs observed the rabbits and were instructed to individually produce a RbtGS score for each rabbit. These rabbits were also recorded at the same time to ensure that those undertaking observations and those watching video recordings were viewing the rabbits during the same time period.
19 videos were played to the level 4 and level 5 SVN group. The level 6 RVN group were only shown videos of the rabbits from the veterinary environment because they had previously undertaken observations at the University Centre. All videos lasted a similar duration (continuous recording of 1 minute) and were each repeated twice. The participants were instructed to complete the RbtGS individually and were not allowed to discuss their observations to ensure validity and accuracy of the results.
The data were then statistically analysed using Minitab and tested using Chi Square for association.
Results
Statistical analysis showed a significant association between the number of correct (327) and incorrect (252) responses produced by each of the participants for all 19 rabbit subjects (Chi2, χ21 = 196.796, p <0.05).
The results in Table 1, show that the participants were able to produce accurate RbtGS scores for all nine rabbits that were healthy. However, the participants produced inaccurate RbtGS scores for the rabbits that had a health condition with only one rabbit (rabbit 3) (assessed to be in pain by a VS) out of seven with an accurate RbtGS of 5 or more.
| Rabbit subjects | Rabbit condition | Mean RbtGS score |
|---|---|---|
| Rabbit 1 | Healthy | 2.45 |
| Rabbit 2 | Healthy | 1.67 |
| Rabbit 3 | Pain/stress | 5.51 |
| Rabbit 4 | Pain/stress | 3.64 |
| Rabbit 7 | Pain/stress | 3.06 |
| Rabbit 8 | Pain/stress | 1.80 |
| Rabbit 9 | Pain/stress | 3.90 |
| Rabbit 10 | Healthy | 3.87 |
| Rabbit 11 | Pain/stress | 3.51 |
| Rabbit 12 | Healthy | 3.70 |
| Rabbit 13 | Pain/stress | 3.67 |
| Rabbit 14 | Pain/stress | 4.29 |
| Rabbit 15 | Healthy | 3 |
| Rabbit 16 | Healthy | 4.90 |
| Rabbit 17 | Healthy | 3.29 |
| Rabbit 18 | Healthy | 3.67 |
| Rabbit 19 | Healthy | 3.22 |
In Figure 1 and Appendix 1, rabbit 1 was considered healthy. The results demonstrate that level 4, level 5 and level 6 SVN and RVNs were able to correctly produce a mean RbtGS score under five. However, the results also indicate that participants with more experience in practice were able to produce the most accurate RbtGS score (level 6 mean RbtGS score of 0.66) compared with (level 5 mean RbtGS score of 1.66 and level 4 mean RbtGS of 2.75).
In Figure 2 and Appendix 2, rabbit 11 was assessed by a VS as having a health condition. The results demonstrate that participants in the group with greater experience and education (level 6) were able to correctly identify the RbtGS as over 5 (mean RbtGS of 5.5). Those with less experience in practice (level 4, mean RbtGS of 4; level 5, mean RbtGS of 3.44) were less able to accurately assess pain in rabbits.
Rabbit 15 was thought to be healthy and was recorded within its normal environment. Table 2 establishes that there was little difference between the number of correct and incorrect responses produced by the VN participants when observing rabbit 15 via live observations or video observations.
| Rabbit 15 Grimace Scale (RbtGS) results | Video observations | Real life observations |
|---|---|---|
| Correct | 21 (84%) | 5 (83.3%) |
| Incorrect | 4 (16%) | 1 (16.7%) |
| Total participants | 25 | 6 |
Discussion
This research found that the RbtGS may not be an optimal tool in identifying signs of pain and stress in rabbits, but with increased experience in practice and level of training, the accuracy improved.
The results in Table 1, indicate that participants were able to correctly recognise rabbits in good health but struggled to produce an accurate RbtGS score for the rabbits that were identified as most likely to be in pain/stress as indicated by a VS. Rabbit three had been diagnosed with arthritis by a VS and had a mean RbtGS score of five. Seven rabbits that were thought to be in pain were all assessed as under five on the RbtGs. Rabbit 8 and rabbit 11 had been diagnosed with ileus by a VS. Ileus is an extremely painful condition and is often accompanied by shock (Ager, 2017). Despite the painful nature of this condition, the participants were unable to identify markers of pain or stress using the RbtGS in these rabbits.
The study identified several elements of the RbtGS, which may have hindered the participant's ability to sufficiently assess pain and stress. The RbtGS asks the user to evaluate the rabbit's ear position, however, this does not take into account breeds of rabbits such as lop-eared varities. There is a potential for these rabbits to be mistakenly identified as painful, as the RbtGS associates a higher pain score for those whose ears are held closer to the back or sides of the body, although this may not be correct for rabbits whose ears naturally fall into this position.
Other challenges included the images used within the RbtGS manual to assist with scoring. Although there is a text description in the manual, the images of the rabbits do not clearly distinguish the markers of pain. This is highlighted in ‘whisker change and position’, with images that are dark and unclear. This was exacerbated by the rabbit's white colouration against a white background, which made it difficult to visualise the whisker position to use as a reference. Therefore, unless the veterinary professional is experienced in using the RbtGS without the use of a manual as a guide, an inaccurate score may be produced.
The RbtGS scores produced by the participants were compared against each of their training levels and experience in practice. This research found that those who had more experience and education in veterinary nursing had a greater ability to assess and score accurately (Figures 1 and 2). Figure 2, highlighted the difference in RbtGS between the participant groups of rabbit 11; all the rabbits were filmed immediately prior to any medical intervention but after initial assessment by the VS, when the rabbit was diagnosed with ileus, with a guarded prognosis.
This suggests that the more clinical experience an individual has, the increased ability to accurately assess pain and stress in rabbits. This is likely because of the accumulation of different experiences in practice that over time aids knowledge and understanding, which transcends into greater accuracy at assessing and recognising pain and stress in rabbits. This theory is supported by Malik and Leach (2017) who stated that pain assessment is primarily learned through practical experiences and continuous professional development (CPD).
Despite this, the results by the level 6 RVN group were still low for rabbit 11 and rabbit 14, both of which were considered to be in pain by a VS. This may highlight that although the fundamental elements to the RbtGS are beneficial, the RbtGS should be re-evaluated and modifications implemented to create a pain score system equal to that used in canine and feline companion animals.
Varga (2016) suggested that a rabbit that is aware it is being observed may normalise its behaviour and hide potential signs of pain and stress. In Table 2, the results show there is little difference in the RbtGs between real life observations and video footage. This suggests that regardless of the type of observation method, the ability to effectively assess pain and stress lies with the RbtGS scoring system and the individual's ability. However, future research could compare differences between pain scoring either by direct or live behavioural observations compared with video footage in order to assess pain.
Limitations
The sample size of 31 is a small proportion of the VNs in the UK, and could be considered too small to use for statistical analysis because of the potential for statistical error due to sample size. In addition only 6 out of 31 participants were qualified RVNs. The small sample size was because of time constraints of the study, as well as access to RVNs, the researchers recommend further studies should be carried out using a larger sample size to increase reliability of the findings.
Sampling method used convenience sampling where participants volunteered to take part in the study. This method although easy and convenient for the researcher to use, is also problematic as it lacks methodological rigor (Curtis et al, 2007). To overcome this, future studies should consider the use of a double-blind randomised study (Cohen et al, 2007).
Observer presence and environment may have also affected the rabbit's behaviour. Rabbits within the veterinary practice may have been displaying signs of stress and anxiety even if they were clinically healthy because of the unfamiliar environment. The presence of an observer can potentially influence the behaviour displayed by the rabbit (Varga, 2016). To overcome this, the use of video recording equipment within the rabbit's accommodation could remove the observer effect. Negative aspects of using video footage are that an additional person is required to ensure the safety of the rabbit if it is not within its accommodation, the cost of the equipment, and the additional time spent reviewing the footage.
If repeated, a pilot study would have been beneficial by providing robustness, clarity, layout, and opportunity for adjustments (McNiff, 2013).
Future recommendations
Potential areas for future research include the re-evaluation of the rabbit pain scale to combine a holistic approach including facial expressions, body posture, and behaviour. It is important that the development of a new pain scale for rabbits is designed for use within the veterinary practice to ensure ease of application to patient care. In addition, the study highlights that there is a need for CPD for newly qualified or inexperienced veterinary nurses around assessment of pain in rabbits.
Further research could compare differences between pain scoring either by direct or live behavioural observations compared with video footage using a much greater sample size.
Conclusion
Although elements of the RbtGS are beneficial, the scope of pain recognition should not be limited to monitoring changes in facial expressions. Considerations for a holistic approach to the rabbit, including the rabbit's body posture and abnormal behaviours, should be added into the RbtGS for it to become a invaluable tool for veterinary professionals.
A practical solution that may assist in gaining a true representation of a rabbit's behaviour is the use of video recording equipment. This eliminates the influence that an observer may have on a rabbit's behaviour when undertaking the RbtGS score, and therefore should assist veterinary professionals to produce an accurate pain score.
Experience and education can aid in accurately assessing pain and stress in rabbits. However, delivering appropriate rabbit care can be a daunting task that RVNs may be apprehensive about. However, RVNs should be encouraged to be involved in the care of rabbits and to repeatedly assess pain in this species as well as undertake CPD in this area. This should be seen as an investment by the practice, as ongoing experience and education will not only improve the standard of rabbit care but also rabbit welfare.