The treatment will vary greatly due to the location of the calculi/sludge and the severity of the problems. Firstly, the rabbit must be stabilised and sufficient analgesia given, since the condition is so painful. Stabilisation may consist of aggressive fluid therapy: intravenous (directly into the vein) or if this is not possible then intraosseous (into the bone marrow) (as long as there is no obstruction of the urinary tract). Subcutaneous fluids are not going to be absorbed sufficiently rapidly if the rabbit is shocked, but are sufficient in the early stages and it is impossible to get enough volume of oral fluid into a rabbit in such cases. The rabbit’s gastrointestinal (GI) tract must be kept moving, so prokinetic medication (Metoclopramide and Ranitidine) should be given and syringe feeding using a herbivore preparation (Oxbow Critical Care or Supreme Recovery) must be commenced at a rate of 50ml/kg/24hr if the rabbit is completely anorexic (less if the rabbit is still eating to some degree). If the rabbit will not tolerate syringe feeding then a naso-oesophageal tube should be placed for the purpose of providing nutrition.
Bloods should also be taken to assess the rabbit’s renal function (urea and creatinine) and the calcium level. This should be interpreted with caution as calcium levels will rise after meals, especially if the foods were high in calcium. A manual PCV (packed cell volume) is also useful to determine dehydration and any evidence of lipaemia (fat within the blood), which may be apparent if the rabbit is going into hepatic lipidosis.
Urinalysis is useful to determine if there are any crystals within the urine. Rabbits who are well hydrated, have a good level of pain relief and whose gastrointestinal tract is working, have a much better chance of surviving major surgery. So, only once the rabbit is stabilised (which may take several days) should surgery be attempted. The only exception to this may be with urethral calculi in buck rabbits who are not able to pass urine and when the calculi can not be pushed back into the bladder, or a urinary catheter inserted. These rabbits are surgical emergencies, and may require immediate life-saving surgery.
Calculi within the urinary bladder are usually the easiest to remove. A procedure called a cystotomy is performed to remove the calculi. Urethral calculi are usually removed by flushing the stone back into the bladder and performing a cystotomy to remove it/them from the bladder. If calculi are detected within one or both ureters (ureterolithiasis), they can often cause hydronephrosis (an enlargement of the kidney due to the blockage of the ureter). Unlike the liver, kidneys do not possess any regenerative powers so it is impossible to improve the kidney’s function once it has been damaged, but kidney parameters will only rise on blood work once over 70% has been lost, so it is possible for a rabbit to live a normal life with some degree of renal impairment. Ureteral calculi can be removed surgically, but it is a difficult procedure to perform on a rabbit due to the small size of a rabbit’s ureter, so referral is often required.
Those rabbits who present with calculi within their kidneys present a difficult dilemma. It is possible to perform a nephrectomy (removal of a kidney) in a rabbit, as long as the other kidney is free from disease. If both the rabbit’s kidneys are affected then it is often deemed unfair to put the rabbit through such a major procedure as a nephrectomy, since the other kidney is not likely to be capable of maintaining sufficient renal function. Attempts have been made to remove calculi from the kidney of a rabbit, but this surgery carries a very high risk of complications.
I am aware of rabbits who have had calculi removed from a kidney, but have sadly died shortly afterwards. And equally those who have gone on to live for several years on one kidney. The rabbit’s quality of life should always be the main consideration for the owner and the veterinary team.