Rabbits and Rodents - Chronic Pain Relief

It is truly frightening how many conditions in small mammals have their roots in chronic pain.

The signs of chronic pain generally consist of one or more of

• Quiet demeanour
• Inactivity and reluctance to move
• Failure to feed or reduced feeding
• Weight loss
• Failure of caecotroph ingestion (rabbits and guinea pigs)
• Aggression or reluctance to be handled
• Alterations in faecal/urinary output or volume
• Lameness
• Anaemia

These signs are non-specific and the pet will often be submitted for veterinary examination for reasons that seem far removed from pain.

These are prey species and rarely vocalise or show overt pain!!

What are the most common reasons?

1.  Dental disease – this is sometimes, though not always, accompanied by drooling in rabbits and rodents. Pain usually results from either.

• Impinging of dental hooks on tongue or cheek – rabbits (and sometimes guinea pigs and chinchillas).
• Root impaction/pain – most common reason in rodents.
• Root abscessation.

I.e. dental disease cannot be ruled out as a source of pain on a simple clinical examination – radiography is required.

2.  Arthritis – this is also extremely common

• Lumbar arthritis – rabbits.
• Stifle arthritis in large breed rabbits or guinea pigs (often due to Vitamin C deficiency).
• Rib junctions (costo-chondral) due to Vitamin C deficiency in guinea pigs.
• Jaws – all species but especially rabbits and guinea pigs where abscessation is relatively common.

Remember that arthritis can occur in any joint following trauma, infection or chronic wear-and-tear. The site is not always easy to determine on examination and radiography helps a lot. Sometimes specialised techniques, e.g. myelography to image the spine, are needed.

3.  Middle ear disease – especially rabbits.

4.  Abdominal problems

• Gut stasis – especially rabbits, guinea pigs and chinchillas. However, remember that most cases of gut stasis (or bloat) are caused by pain from some other place!
• Gut foreign bodies.
• Abdominal tumours - especially uterine adenocarcinoma in rabbits.
• Urinary problems – sludging or stone formation. Again, this is often a problem that usually occurs due to chronic pain and resultant urine retention.

Once identified, pain relief can be started. We are fortunate that there are a growing number of drugs that appear effective and safe enough for use in rabbits and rodents.

However, often the dose rates are very different between cats/dogs and small mammals – this often means that rabbits and rodents are often given what appear to be huge doses of pain killers – yet this is often what they need!

In some cases it may be appropriate to take a blood sample to check liver/ kidney function before starting courses of analgesia.

In chronic diseases such as arthritis and dental disease, analgesia may be required lifelong. While there may be potential for drug side-effects (these are rare and can be minimised by appropriate dosing and drug selection for each individual). It is vital to remember that chronic pain is very debilitating to the patient and far more likely to be harmful than the painkilling drug!