Rabbits have always been a popular companion animal. Due to increased levels of client knowledge, veterinary practices are expected to give species specific care both medically and surgically, but how can veterinary practices really improve this care to ensure that it is gold standard every time? Primarily it is the veterinary nurses (VNs) who provide the medical, environmental and client care. Failure to identify stress or pain in rabbits could have potentially fatal consequences. Initially this article will explore a definition of pain and why rabbits are so difficult to assess. A review of literary evidence will discuss in what areas practices can ensure species-specific care and recommended analgesia protocols, concluding with how VNs can be at the forefront of improving both practice and client education.
What is pain?
Pain is both an individual and a subjective experience. An accurate assessment of pain is crucial to relieve animal suffering as part of our veterinary oath. Pain can be acute and chronic. Acute pain will normally incite a demeanour/postural change in the patient that is recognisable and usually responds well to analgesia. Chronic pain can be harder to recognise and treat as there may not be an obvious cause and the patient may have adapted their physiological response (Stasiak and Hellyer, 2003).
Kohn et al (2007) merge the International Association for the Study of Pain (IASP) and the USDA's more anthropomorphic view to form the following statement:
‘Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage, and should be expected in an animal subjected to any procedure or disease model that would be likely to cause pain in a human.’
Pain can be sub-catagorised as physiological or pathological. Physiological pain is caused by noxious stimuli activating high threshold sensory nerve fibres. This reflex allows the animal to rapidly withdraw, resulting in minimal tissue damage. Pathological pain is caused by actual tissue damage and can be further catagorised as:
Visceral pain and somatic pain can vary in their response to analgesia. The IASP, 2012, state that visceral pain is sensed as arising from the internal organs of the body and could be caused by:
How does this affect rabbits?
Pain and stress in rabbits is invariably linked. Pain can cause stress, but so can a trip to the veterinary practice to treat the pain the rabbit is experiencing. Varga (2014) states that the effects of pain and stress in rabbits are significant as they can trigger a catecholamine or corticosteroid release, which in extreme cases can cause heart failure and death. The release of catecholamines indirectly stimulates the sympathetic nervous system which inhibits gut motility. Stress increases gastric acidity and could cause gastric ulceration in rabbits and can also reduce renal blood flow and cause oliguria.
Why is pain in rabbits difficult to assess?
It can be challenging to differentiate pain from anxiety in rabbits. Rabbits can often be described as ‘not themselves’ by an owner. After transportation, a waiting room filled with the smell of predators, then being placed on a table and handled by an unfamiliar human could make a ‘prey species’ alter their normal behaviour. Easily measured physiological parameters such as respiratory and heart rate will become useless. Rabbits will also rarely vocalise in response to minor pain (Keating et al, 2012). Table 1 lists the various responses to pain.
| Fewer/small faecal pellets | Teeth grinding (bruxism) |
| Anorexia | Strained facial expression/bulging eyes |
| Half closed/unfocused eyes | Rapid shallow breathing/aerophagia (Figure 2) |
| Diarrhoea | Mouth breathing |
| Aggression | Lameness |
| Pushing abdomen into floor | Ataxia |
| Immobility | Polydipsia/polyuria |
| Lethargy | Head and neck extended |
| Isolation/withdrawal | Pilo erection |
| Grooming changes | Self mutilation |
| Vocalisation | Drooling |
| Stretching with back arched | Any change from the norm |
| Hunched posture (Figure 1) | Stinting of palpation |
| Poor body condition score | Poor coat condition |
When should pain recognition and control be used in a veterinary environment?
There are a number of situations when pain recognition and control can be addressed in the veterinary practice:
Clinical signs
A series of studies by Flecknell and Roughan (2004) demonstrated that understanding what is normal behaviour for a species is imperative in identifying pain. Laboratory rats underwent abdominal surgery and were given variations of pain relief. They were then placed in an observation cage for 10 minutes and videoed. The results of the initial study in 2000 were inconclusive as the rats were given the opioid buprenorphine, this drug was found to have had a profound effect on normal behaviour. Further studies used carprofen and ketoprofen, and successfully showed behavioural differences between the rats that had received analgesia and those that had not.
Experienced staff such as veterinarians, technicians and research workers were shown the videos and were unable to identify the rats that had been given analgesia until they were shown a short recording that educated them of key pain-related behaviours. This demonstrates that education of owners and staff is paramount. Table 1 lists behavioural parameters that can often be overlooked.
Physiological parameters such as temperature, heart rate and respiratory rate can increase due to environmental stress and therefore are not reliable indicators of pain, but should be used alongside clinical symptoms. The biochemical parameters to measure pain or stress are corticosteroid, catecholamine and glucose levels. The latter being a useful measurement in first opinion practice; a glucometer should be available in every practice.
Hypoglycaemia is usually accompanied by anorexia and gut stasis. It may signify a hepatic issue but it could also be an indication of septicaemia. A rabbit that is hypoglycaemic should be put on appropriate fluid therapy and a gut stasis protocol should be started immediately (Varga, 2014)
Hyperglycaemia is a common finding in rabbits as blood glucose levels can increase with handling. A level of 8.5 mmol/litre is experimentally acceptable. Hyperglycaemia can also be seen with acute pain, such as with intestinal obstruction where glucose levels may reach 20–25 mmol/litre. This should normalise once the issue is successfully treated. Hyper-glycaemia can also indicate when a patient is reaching the terminal stages of gut stasis (Harcourt-Brown and Harcourt-Brown, 2012).
Rabbit grimace scale
The rabbit grimace scale (RbtGS) examines five actions that have been shown to increase with severity of pain. The actions comprise:
The key to the RbtGS can be found at https://www.nc3rs.org.uk/rabbit-grimace-scale.
Rabbits are marked 0–2 according to severity. Keating et al (2012) applied the RbtGS to their study when assessing the efficacy of EMLA cream as a topical analgesic for ear tattoos. They concluded that the RbtGS was a reliable method to assess rabbit pain. The scale relies on user experience and interpretation and Flecknell and Roughan (2004) suggest a patient assessment using the scale lasting 5–10 minutes, repeated every 2 hours. This poses a time-scale limitation that may not be practical in a busy veterinary environment. In contrast Leach et al (2011) showed participants videos of New Zealand rabbits demonstrating postoperative pain. They concluded that observing facial responses resulted in the incorrect assessment of pain; observing the hind quarters of the patients produced an 88% score of correct pain identification, compared with an 18% score when assessing a facial response to pain.
Improvements within the practice
Once a patient has had a veterinary health check, clients can book in with a VN for a ‘Rabbit Clinic’ where information is given regarding husbandry, diet, normal and abnormal behaviour. This will help bond clients to the practice. If the rabbit is to be a children's pet, then the importance of gentle, calm handling and providing mental stimulation should be explained, as well as the need for a companion (Stapleton, 2016).
The study by Keating et al (2012) demonstrated that EMLA cream was an effective local method of pain relief in rabbits. This can be adapted to using EMLA cream prior to placing an IV catheter in the lateral ear vein, or prior to taking blood samples. Lichtenberger et al (2009) favours using low dose midazolam (0.25 mg/kg) alongside an opioid such as butorphanol (0.2 mg/kg) or buprenorphine (0.04 mg/kg) intramuscular (IM)/intravenous (IV) as a sedative to help anxious, fractious rabbits that are suspected of being in pain. It will allow placement of IV cannula, sub cutaneous fluids, x-ray etc. This is given as a simple sedative even in unstable patients, to reduce stress is to increase the rabbit's chances of survival. Lichtenberger notes that rabbits in respiratory distress are able to breath more easily with the afore mentioned sedation, due to the anti-anxiety effects of the midazolam. If the anxiety is managed, then the symptoms of pain may be easier to identify. Table 2 shows drug properties and recommended doses.
| Drug | Pros | Cons | Dose |
|---|---|---|---|
| Meloxicam | Good anti-arthritic effective |
Renal/hepatic monitoring with long-term use. |
0.5–1.5 mg/kg once daily (sid), subcutaneously (sc), per os (po) |
| Carprofen NSAID | Antipyretic |
As above |
4 mg/kg sid sc 1.5 mg/kg twice daily (bid), po |
| Buprenorphine Opioid | Good analgesia |
Sedation |
0.01–0.05 mg/kg q6–12 hours intraveously (iv), sc |
| Butorphanol Opioid | Pre-emptive pain relief if used as part of sedation | Weak analgesic effects |
0.1–0.5 mg/kg iv, intramuscularly (im), sc |
| Fentanyl Opioid | Pre-medication/sedation/anaesthesia |
Reduced efficacy with rapid hair growth |
0.2–0.3 ml/kg |
| Ketamine | Combination sedation/anaesthesia | Not recommended for analgesia | 20–50 mg/kg im |
It is well known that rabbits are susceptible to forming abdominal adhesions post abdominal surgery. Currently, the author's practice ensures that the surgeons gloved fingers are sluiced with warmed saline, as are surgical swabs. This is then followed by 10 mls of saline into the abdominal cavity prior to closure. In an effort to reduce abdominal adhesions in humans, a study by Akerberg et al (2012) established that by adding a-polyL-lysine, poly-L-glutamate and 2.54% glycerol solution to saline, abdominal adhesions were significantly reduced postoperatively in rabbits.
VNs could consider using the RbtGS in practice postoperatively, and provide feedback as to how useful they found the scale. Demonstrating syringe feeding and medication techniques to clients will increase client compliance and post-treatment success rates.
Conclusions
As rabbits are increasingly becoming a true companion animal, it is vital that veterinary surgeons and veterinary nurses educate themselves and their clients on gold standard care. The rabbit's ability to disguise illness means that subtle changes in behaviour are true indicators of pain. Up to date analgesia protocols and techniques for handling rabbits improve in-house care. Yet again, it is today's VNs that are able to take that giant leap for bunnykind.