Rabbits are prey animals and so can die of pain whereas dogs in pain will just cry.

This apparently extreme statement is fundamental to ensuring rabbits are not just given optimum care periopertively but survive the procedure. Perhaps because rabbits do not show overt signs of pain (e.g., vocalisation) it is more difficult to realise their condition. Rabbits in pain will tend to become anorexic, which may lead to irrevocable hepatic lipidosis within days. Stomach ulcers develop under stress, further exacerbating the anorexia. Ileus develops in the painful rabbit, which is itself an intensely painful condition, and so the rabbit is now trapped in a vicious circle of pain and ileus until death. On a positive note, these patients respond very well to a wide range of analgesics, doses are well reported (particularly from the laboratory literature) and their small size means it's relatively cheap to give them excellent analgesia! In circumstances of likely pain, such as orthopaedic surgery or 'primary' ileus, it is advisable to reach straight for high-level medication such as opioids or partial agonists such as fentanyl, pethidine, butorphanol and buprenorphine. Merely administering a non-steroidal anti-inflammatory drug (NSAID) in such situations is barely adequate and in some cases, as previously described, could lead to life-threatening pain. It is also wise to note the length of action of the chosen analgesic in the rabbit and ensure continuing cover is given; rechecking at the expected time given the duration of action of the medication chosen and remembering that signs of pain in the rabbit include anorexia, lack of faecal production, excessive drinking, reluctance to move or interact (often mistaken for 'prolonged recovery from anaesthesia') or, more rarely, increased aggression.

The old maxim that there is no safer anaesthesia than the one you are familiar with is just as true for the rabbit as for other species. To that end, I don't aim to promote a perfect drug combination. There is a multitude of safe anaesthetic protocols for the rabbit (as any textbook aimed at laboratory rabbit researchers can tell you) as well as those, such as the UK practice favourite 'triple combination' of ketamine, medetomidine and buprenorphine, to recently published alfaxalone as well as the old favourite 'Hypnorm' (fentanyl/fluanisone) with midazolam. For maintenance, isoflurane via intubation has become standard practice, although the old staple of halothane gave better analgesia and was not the 'rabbit killer' now referred to in legend.

The challenge with rabbit anaesthesia is less the combination chosen than the state of the rabbit patient. Rabbits are peculiar in that every single pet rabbit will have a degree of pneumonia (usually caused by Pasteurella multocida). This disease should be considered endemic in both the pet and wild rabbit population; Pasteurella-free rabbits only occur artificially in laboratories. So, the realisation that every 'apparently healthy' pet rabbit you see has varying degrees of pneumonia and lung destruction, explains the highly variable response to anaesthetic dosages and the relatively higher anaesthetic mortality rate in this species compared with dogs or cats. This understanding is not an excuse to avoid adequate sedation, analgesia or anaesthesia of the rabbit when required; just that doses should be carefully calculated and even titrated to effect wherever possible and certainly the patient needs a careful examination to assess the degree of lung disease. The avoidance of intramuscular injection (it's painful, generally unnecessary, takes longer to reach maximal effect and is 'all or nothing' in one dose) and instead using intravenous dosing to effect gives the vet much more control over the depth of anaesthesia for instance.

This lecture will outline a number of anaesthetic protocols as well as safe practice and tips on how to manage these patients in pain.