A conversation between The Guinea Pig Vet, Ellie Whitehead and guest blogger Sue Tate, Founder of Cavy Corner - Guinea Pig Sanctuary
It has long been my feeling that the provision of pain relief for guinea pigs is something we could do better. This is something that was recently compounded by a conversation I had with my friend, Sue, at Cavy Corner. In this blog I want to highlight the problems that exist in providing adequate pain relief but also increase awareness of the options that are available.
The use of pain relief, or analgesia, is broadly speaking based on two things; an acknowledgement of the existence of pain (as well as the degree of pain) and a knowledge of the possible analgesic agents available. Since guinea pigs are prey species they are very good at hiding signs of illness and pain. However, careful monitoring of a guinea pigs posture, behaviour and vocalisations can be observed as indicators of pain. These observations are best achieved in a hands-off way, from a distance, or utilising CCTV. A tool to make the determination of the degree of pain more objective rather than subjective has been used in human, dog and cat
medicine for some time.
These tools are called pain scales, they give a number to the severity of pain observed based on a set of criteria, such that two different people observing the same patient will reliably award the same score. More recently a pain scale, known as the grimace scale, was developed for rabbits and then rats and mice. The grimace scale uses changes in ear position and facial expression to denote degree of pain. Unfortunately a verified pain scale for guinea pigs does not yet exist. This
makes the first task, acknowledging the existence and degree of pain, more challenging.
Analgesics available for guinea pigs are, on the surface, very limited. There is only one pain relief medication that has received a license for use in guinea pigs. Veterinary surgeons are required to prescribe medications under what is known as the prescribing cascade. This requires you to prescribe a medication that has a license for that use, in that species at the licensed dose
first; unless there is no such medication available, or there is an evidenced reason not to. In the majority of cases pain relief for guinea pigs needs to be prescribed ‘off license’ under the cascade.
The choice of which pain relief to use and at what dose should be evidence based. Where this evidence does not exist (as is sometimes the case with guinea pigs) the decision may be based on extrapolation of information from other species and personal experience. It should be noted that drug absorption in hindgut fermenters, such as guinea pigs, differs significantly from other species.
Oral analgesic options:
In my opinion non-steroidal anti-inflammatories (NSAID’s) are the mainstay of pain relief in this species, in both oral and injectable forms. Research published by Ghent University entitled ‘Pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs (Cavia porcellus)’ suggests the use of doses up to 1.5mg/kg bodyweight twice daily for higher levels of pain. In my
experience, doses of this level produce observably better results in controlling pain than the licensed dose for this drug. Other options include gabapentin and tramadol.
Injectable pain relief that your vet may use include meloxicam (as discussed above) and opioids (this class includes drugs called buprenorphine, methadone, morphine, fentanyl and butorphanol).
If surgery is being performed by your vet then nerve blocks and splash blocks can be utilised to reduce post-operative pain.
Thoughts from Sue at Cavy Corner:
As Ellie states the consequences of insufficient pain relief are serious and much too common. Being in pain can lead to a range of new complications arising or exacerbate the original issue; for example a Guinea receiving dental treatment who has insufficient pain relief may be more reluctant to attempt to eat independently. Following surgery Guineas may pull out their own stitches or bite at a wound, possibly even negating the benefit of the original procedure. Instances of Guineas being sent home after surgery without any analgesia are common, as are doses which are too small or spaced too far apart to be effective. In his webinars, eminent Vet John Chitty BVetMed, CertZooMed CBiol, MSB, MRCVS makes reference to the need for adequate analgesia and the fact that Vets can use their clinical judgement in an individual situation to prescribe off -license. As an owner seek out Vets who are interested in Guinea Pigs and willing to listen to your concerns.
Owners know their own Guinea best so learn to recognize the pain indicator signals so that you can accurately report the facts to your Vet. Caring for a Guinea Pig with un-managed pain is a distressing situation for both Guinea and owner and often involves multiple clinical visits, ( as owners try to source help) additional stress on an already sick Guinea and further expense.
The sheer number of Guinea Pig Rescues within the UK demonstrates what a popular animal they are, and that they deserve good basic care. I greatly respect the Veterinary profession, their training and skills but more needs to be done to meet the basic needs of the Guinea Pig.
In summary good observation of your guinea pig and their behaviour will allow you to pick up on signs of pain and the severity of that pain. It is important that this pain is then managed appropriately. A guinea pig that is still in pain may not eat, or move, may develop gut stasis or illeus and in extreme cases they may self mutilate. Most importantly a guinea pig still in pain is not receiving the level of care they deserve.