Urolithiasis in Lagomorphs and Ferrets

Disease Summary

Alternative Names (Synonyms)

• Urinary calculi
• Renal calculi
• Ureteral calculi
• Cystic calculi
• Urethral calculi
• Urinary lithiasis

Disease Type

Infectious/Non-Infectious Agent associated with the Disease

General

• If the concentration of stone-forming ions in urine is increased, or there is anything promoting aggregation of crystals, uroliths may occur. (B600.14.w14)

Lagomorphs

• Associated with hypercalciuria (Hypercalciuria in Rabbits).
• A diet high in calcium will result in higher calcium excretion via the urine. This, together with the alkaline pH of rabbit urine, may increase the risk of precipitation of calcium salts. (J376.121.w1)
  • A link with excessive dietary calcium has not been proven. (B600.14.w14)
• Mechanical obstruction of the urinary tract may lead to urolithiasis in rabbits; this has been proven experimentally. (B600.14.w14)
  • Sludgy urine, adhesions, abscesses or tumours may cause mechanical obstruction. (B600.14.w14)
• Other factors which may be associated with urolith development include high levels of oxylate in the diet, restricted water intake, urine retention, cystitis and changes in urinary pH. (B600.14.w14)
• Obesity and lack of exercise may predispose to development of urolithiasis. (B602.18.w18)

Ferrets

• Normally urolithiasis is related to diet, as plant proteins make the urine alkalinized (pH 6) which causes crystalluria and stone formation. (B232.13.w13, B602.4.w4, B629.13.w13)
  • One study showed that increased protein in ferret diets reduces the pH level of the urine, which reduces struvite formation. Another study showed, however, that urolithiasis can be caused by poor quality meat or too much cereal protein in the diet. (B631.27.w27)
• Magnesium ammonium phosphate (struvite) uroliths are the most common uroliths found in ferrets. (B232.13.w13, B602.4.w4, B602.12.w12, B629.13.w13)
• Crystals and uroliths composed of cystine, calcium oxylate and calcium hydrogen phosphate (brushite) have been described. (B631.27.w27, J213.6.w4)
• Nondietary-related urolithiasis is associated with urease-producing bacteria, such as Staphylococcus spp., Pseudomonas spp. and Proteus spp., which cause urinary alkalinity, (B602.4.w4, B629.13.w13, J213.6.w4) or with increased urinary excretion of minerals, and/or release of cellular proteins or polymerisation of urinary mucoproteins, due to renal injury. (B629.13.w13, J213.6.w4)
• Formation of stones can occur after a urinary tract infection. (B232.13.w13)
• Metabolic abnormalities may be involved in production of uroliths occasionally. (J213.6.w4)
• There may be a genetic component or genetic predisposition. (B631.27.w27, J213.6.w4)

Infective "Taxa"

• Proteus spp.
• Pseudomonas spp.
• Staphylococcus spp.

Non-infective agents

Physical agents

References

Disease Author

Referees

Major References / Reviews

Code and Title List

Ferrets:
B232.13.w13, B602.2.w2, B602.4.w4, B602.12.w12, B629.13.w13, B630.11.w11, B631.19.w19, B631.23.w23, B631.27.w27, B631.32.w32
J34.17.w4, J34.24.w4, J34.28.w1, J213.6.w4

Other References

Code and Title List

Detailed Clinical and Pathological Characteristics

Clinical Characteristics

• General: depression and lethargy, anorexia and weight loss. (B602.18.w18, J8.42.w1, J513.6.w1)
• Specific: haematuria, stranguria, hunched posture, tooth grinding, perineal urine scald. (B602.18.w18, J34.24.w3)
  • Haematuria and stranguria are not always present. (J34.24.w3)
• May be subclinical. (B602.18.w18)
• In one case, signs of intestinal obstruction (due to a 12 mm diameter calculus wedged in the pelvic inlet). (J3.96.w4)
• Anorexia and abdominal distension. (J4.217.w4)
• The bladder may be small and thickened, or an abdominal mass may be palpable. (J34.24.w3)
  • If the urethra is obstructed, the bladder is turgid. (B602.18.w18)
• If calculi have led to hydronephrosis or hydroureter, the enlarged kidney or enlarged ureter may be palpable. (B602.18.w18)
• If renal calculi are involved, eventually signs of renal failure. (B600.14.w14)
• Signs of severe pain, and anorexia, were noted in rabbits with ureteral uroliths. (J3.160.w4)

Clinical pathology

• Urinalysis
  • Crystalluria (often calcium oxylate crystals; calcium carbonate, ammonium phosphate and monohydrate crystals may be present. (B602.18.w18)
  • Often proteinuria and haematuria. (B602.18.w18)
  • If bacteria are present, a cystocentesis sample should be submitted for culture (see: Cystitis in Elephants, Bears and Rabbits). (B602.18.w18)
• Biochemistry: raised blood urea nitrogen (BUN), creatinine and phosphorus if renal calculi have led to renal failure. (B600.14.w14, J513.6.w1)
• See: Clinical Pathology of Lagomorphs

• Clinical signs are similar to those in other species. (B602.12.w12)

  Urinary:

  • Stranguria (difficulty passing urine). (B602.12.w12, B629.13.w13, B631.27.w27, J34.24.w4, J213.6.w4)
    • Note: Small amounts of faeces may be passed during straining, therefore the owner may report constipation or diarrhoea. (J213.6.w4)
  • Dribbling urine/urinary incontinence. (B602.4.w4, B629.13.w13, J34.17.w4, J34.24.w4, J213.6.w4)
  • Frequent urination. (B232.13.w13, B629.13.w13, B631.27.w27)
  • Straining, which can lead to a rectal or vaginal prolapse. (B232.13.w13)
  • Haematuria. (B232.13.w13, B602.4.w4, B602.12.w12, B629.13.w13, B631.27.w27, J34.24.w4, J213.6.w4)
  • Vocalisation when urinating. (B602.4.w4, B629.13.w13, J213.6.w4)
  • Licking of the perineal area. (B232.13.w13, B602.4.w4)
  • Wet fur and skin irritation around the preputial and perineum region. (B232.13.w13, B602.4.w4, B629.13.w13, J213.6.w4)
  • Distended bladder palpable on abdominal palpation in obstructed ferrets. (B602.4.w4, B629.13.w13)
  • Calculi and sand palpable in the bladder if there is no obstruction. (B602.4.w4)

  General:

  • Abdominal discomfort. (B631.27.w27)
  • Vocalisation (due to pain) on abdominal palpation. (B629.13.w13)
  • Lethargy. (B602.4.w4, B629.13.w13, J34.17.w4, J34.24.w4)
  • Inappetence. (B602.4.w4, B629.13.w13)

  Clinical pathology

  • Urinary alkalinization. (B629.13.w13)
  • Post-renal azotaemia and uraemia. (B631.27.w27, J34.17.w4)

Incubation

• --

Mortality / Morbidity

• --

• Common in pet rabbits. (B600.14.w14, J34.24.w3, J513.6.w1)

• The prognosis for ferrets with bilateral renal calculi is guarded. (B631.27.w27)
• Urinary obstructions can cause major organ disturbances, bladder rupture or structural damage to the kidneys, and may be fatal. (B602.4.w4, B629.13.w13, J34.17.w4)

Pathology

• Bladder: 
  • Calculi. (J495.37.w1)
    • Note: calculi in the bladder can be an incidental finding. (J495.37.w1)
  • Haemorrhagic or chronic cystitis may be present. (J495.37.w1)
  • In one rabbit, the bladder was distended, containing 300 mL blood-tinged urine and 500 mL sand-textured calculi (total bladder contents weighed 1.12 kg). Additionally, the wall of the bladder was thickened and the mucosal surface was marked with fine paintbrush haemorrhages. (J4.217.w4)
    • The sand was revealed by analysis to be calcium carbonate and oxylate dihydrate. (J4.217.w4)
  • In three rabbits with cystic calculi, one had a hard round light grey stone, 25 mm diameter, another a more brittle yellow round stone, 20 mm diameter with a rough, irregular surface, while the third had an oval yellow-tan mass, 7 x 5 cm, filling the bladder; the mass was a mucous-like matrix binding finely granular material. (J495.32.w1)
• Renal: 
  • Calculi may be found in the renal pelvis. (B600.14.w14)
    • A 1 cm diameter yellow calculus was considered an incidental finding in a rabbit which died from purulent pneumonia. (J4.194.w2)
  • There may be pus around the calculi. (B600.14.w14)
• Ureters:
  • Calculi may be found in the ureters. (B600.14.w14)
  • There may be pus around the calculi. (B600.14.w14)

Gross pathology:

• Renal:
  • Hydronephrosis secondary to an obstruction. (B631.27.w27)
• Bladder: 
  • Presence of calculi (bladder stones), which may vary in size. (B631.32.w32)
  • The bladder may be distended. (B629.13.w13)
  • Bladder rupture may be present due to urinary tract obstruction. (B629.13.w13)
• Ureters:
  • Calculi may be found in the ureters. (B629.13.w13)

Human Health Considerations

Disease has been reported in either the wild or in captivity in:

• Domestic rabbits. (B600.14.w14, B602.18.w18, J4.217.w4, J26.15.w1, J34.24.w3, J495.37.w1, J513.6.w1)
• 14% of ferrets that were fed a commercial dry dog food, which was high in protein, were found to have uroliths. (B232.13.w13, B602.4.w4)

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

• Mustela putorius furo - Ferret
• Oryctolagus cuniculus domesticus - Domestic European rabbit

(List does not contain all other species groups affected by this disease)

Disease has been specifically reported in Free-ranging populations of:

• --

Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

Host Species List

• --

(List does not contain all other species groups affected by this disease)

General Information on Environmental Factors/Events and Seasonality

• --

Regions / Countries where the Infectious Agent or Disease has been recorded

• --

Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

• --

General Information on Investigation / Diagnosis

• Urine cloudy or clay-coloured. (J3.96.w4)
• Sand-like material in the bladder. (J3.96.w4)
• Palpable abdominal mass/ palpable calculi in the bladder. (J3.96.w4, J495.37.w1)

Urinalysis 

• Crystalluria (often calcium oxylate crystals; calcium carbonate, ammonium phosphate and monohydrate crystals may be present. (B602.18.w18)
• Often proteinuria and haematuria. (B602.18.w18)
• If bacteria are present (see: Cystitis in Elephants, Bears and Rabbits), a cystocentesis sample should be submitted for culture . (B602.18.w18)
  • See: 
    • Clinical Pathology of Lagomorphs
    • Cystocentesis of Rabbits

Haematology and biochemistry

• For general assessment of renal function and prognosis. (B602.18.w18)
• Creatinine and urea may be raised if renal function is compromised e.g. with calculi in the ureters. (J8.42.w1)
• Ureamia. (B232.13.w13, B631.27.w27)

Radiography

• This is usually diagnostic. (J34.24.w3)
  • The bladder may be of normal size or may be distended. (J4.217.w4)
  • Uroliths in rabbits are usually composed mainly of calcium and are radiodense. (J34.24.w3, J513.6.w1)
  • A small amount of bladder "sand" is an incidental finding in rabbits. (B602.18.w18)
  • There may be a single calculus or less commonly more than one calculus in the bladder. (J513.6.w1)
  • There may be radio-opaque urolith "sand" in the dependent part of the bladder; in an extreme case the whole bladder may be distended and radio-opaque, and may displace other abdominal organs cranially. (J4.217.w4)
  • The bladder should be regular in shape, the mucosal borders should be regular and any mass (calculus) should not be attached to the bladder wall (compared with bladder neoplasia, in which the bladder is typically irregular in shape, the mucosal borders are irregular and any mass is attached to the wall of the bladder. (J4.217.w4)
• Check radiographs carefully for calculi in the kidneys, ureters and urethra. (B600.14.w14, B602.18.w18)
  • Calculi may be visible in the kidneys or ureters. (J3.160.w4)
  • It is important that the radiograph covers the whole pelvis if urethral calculi are to be detected. (J513.6.w1)
  • Note: the prognosis is poor with renal calculi. (B600.14.w14)
  • There may be renal enlargement associated with renal or ureteral calculi. (J8.42.w1)
• Intravenous pyelography can be used for evaluation of renal function in rabbits with renal calculi. (B602.18.w18, J513.6.w1)
• See: Imaging in Lagomorph Diagnosis and Treatment

Ultrasonography

• The bladder as well as the kidneys, ureters and urethra can be evaluated. (J4.217.w4)
• Ultrasonography can distinguish discrete calculi within a dilated, diffusely opaque bladder. (B602.18.w18)
• Ultrasonography can distinguish between hydronephrosis and multiple renal cysts. (B602.18.w18)
• With nephrolithiasis, intense hyperechogenicity of the affected kidney and adjacent shadowing are seen. (J513.6.w1)
• Real-time B-mode ultrasonography may show that when the bladder is shaken, calculi move within the bladder lumen or along the bladder wall. (J4.217.w4)
• Viewing from multiple angles should indicate whether or not masses are attached to the bladder wall. (J4.217.w4)
• See: Imaging in Lagomorph Diagnosis and Treatment

• Distension of the bladder may be found on abdominal palpation. (B232.13.w13, B602.4.w4, B629.13.w13)) Note: This is will be uncomfortable/painful and may cause vocalisation. (B629.13.w13)
• Cystic calculi may be palpable in ferrets without a urinary obstruction. (B602.4.w4)
• Once the patient is stabilized, a full work up can be carried out to identify the cause of the urinary obstruction.  (B629.13.w13)

Urinalysis 

• Urine analysis should be carried out to identify any crystals; bacterial culture and sensitivity testing should be carried out. (B602.2.w2, B602.4.w4, B629.13.w13, B631.27.w27, B631.32.w32, J34.24.w4) Dipstick (B631.32.w32), specific gravity and sedimentation for standard analysis. (B630.11.w11)
  • Increased mineral excretion. (B629.13.w13)
  • The most common crystal type is struvite. (B232.13.w13, B602.4.w4)
  • Stones should be submitted for analysis, so that the correct medication can be given. (B602.12.w12, B629.13.w13)
• Urease-producing bacteria such as Staphylococcus spp. or Proteus spp. may be detected. (B629.13.w13)

Haematology and biochemistry

• A complete blood count and biochemistry should be performed, to identify any infection or metabolic abnormalities. (B602.4.w4, B629.13.w13, B631.32.w32, J34.24.w4)

Radiography

• Radiographs can assist with identifying the location of crystals and in detection or ruling out of other conditions such as prostatomegaly. (B232.13.w13, B602.4.w4, B629.13.w13, B631.27.w27, B631.32.w32, J34.24.w4) 
  • Note: Calculi lodged near the os penis are difficult to detect. (B602.4.w4)
  • Struvite calculi vary in radiodensity. (J213.6.w4)
• Contrast cystourethrography may assist visualisation of uroliths in the penile urethra. (J213.6.w4)
• An intravenous pyelogram is useful to highlight calculi. Use 720 mg iodine/kg, given via the cephalic vein which is easily accessible. Non iodine-containing medium can be used intravenously to carry out an excretory urogram. This should be done only if the ferret is properly hydrated. (B631.19.w19)
• See: Imaging in Ferret Diagnosis and Treatment

Ultrasonography

• Ultrasonography (J34.24.w4) can be used to detect radiolucent stones, investigate prostatomegaly, or prostatic cysts and may assist in ruling out other diseases, as well as assisting in evaluating the bladder, ureters, kidneys and adrenals. (B602.4.w4, B629.13.w13, B631.32.w32, J213.6.w4)

• Cystocentesis of Rabbits
• Environmental Assessment
• History & Documentation
• Physical Examination of Mammals
• Clinical Pathology of Lagomorphs
• Clinical Pathology of Ferrets
• Imaging in Lagomorph Diagnosis and Treatment
• Imaging in Ferret Diagnosis and Treatment
• Necropsy of Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

Similar Diseases (Differential Diagnosis)

• Hypercalciuria in Rabbits
• Urinary bladder neoplasia. See: Naturally Occurring Neoplasia in Lagomorphs

• Bacterial Cystitis in Ferrets. (B631.App1.w32)
• Prostatic Cysts in Ferrets (causes uretheral compression). (B629.13.w13, J213.6.w4)
• Neoplasia in Ferrets. (B629.13.w13, B631.App1.w32, J213.6.w4)
• Pyometra in Ferrets. (B631.App1.w32)
• Renal infarcts. (B631.App1.w32)
• Ovarian disease. (B631.App1.w32)

Specific Medical Treatment

• Analgesia if the rabbit shows signs of pain. NSAID e.g. meloxicam can be used (care with use of NSAIDs if there may be significant renal dysfunction). Opioids may be used (e.g. buprenorphine. (B601.9.w9)
• For non-surgical removal of non-obstructive calculi from the renal pelvis or ureters, subcutaneous or intravenous fluids may e used to increase "flushing" of the urinary tract. (B602.18.w18)
  • Manual expression of the bladder daily for 2-3 days assists in removing crystals or "sand" from the bladder. (B602.18.w18)

Note: In a ferret with urinary obstruction, initial alleviation of this problem and correction of metabolic disturbances are essential: see section below, General Nursing and Surgical Techniques.

• Analgesia. (B631.27.w27)
• A broad spectrum antibiotic should be given after surgery or if an infection is suspected. Antibiotics should be based on culture results. (B602.4.w4, B631.27.w27)  
  • Potentiated sulphonamides should be given for ten to fourteen days. (B232.13.w13, B629.13.w13)
  • Other broad spectrum antibiotics that can be used are amoxicillin or cephalexin. (B602.4.w4) 
• Appetite stimulants may be required. (B631.27.w27)
• Change the ferret's diet slowly to an animal protein based diet. (B602.4.w4)

Note:  

• Struvite-dissolving diets are not recommended as part of treatment for ferrets; they do not contain enough protein and they are unpalatable. (B629.13.w13, J213.6.w4)
• If the diet is appropriate, urinary acidifiers are unnecessary. (J213.6.w4)

• Food and Feeding for Mammals
• Treatment and Care

General Nursing and Surgical Techniques

• Treat any urine scalding. 
• Encourage weight loss in overweight rabbits. (B601.9.w9, B602.18.w18)
• Reduce calcium intake to reduce sediment formation/retention and formation of uroliths: modify the diet to mainly meadow hay or timothy hay, plus moderate quantities of green leafy vegetables, some root vegetables and only small amounts of pellets, which must be based on timothy grass. Avoid alfalfa (hay or pellets) and vitamin/mineral supplements, and limit intake of kale, carrot tops, clover and dandelion. (B601.9.w9, B602.18.w18, J8.42.w1)

To remove uroliths

• Urohydropropulsion to remove small, round urocystoliths: (B601.9.w9, B602.18.w18)
  • Give diazepam to relax the smooth muscle of the urethra, and give an appropriate analgesic (butorphanol or buprenorphine, since expression of the bladder is painful. (B601.9.w9, B602.18.w18)
  • Under general anaesthesia, place a urethral catheter and instil 4-6 mL/kg sterile saline to produce moderate bladder distension. (B601.9.w9)
  • Remove the urethral catheter, hold the rabbit upright (spine vertical) and use firm, steady digital pressure to manually express the bladder. Repeat until all uroliths have been expelled (confirm radiographically). (B601.9.w9, B602.18.w18)
  • Take care in male rabbits in particular that the uroliths are sufficiently small to pass through the urethra.
  • Note: this procedure may be followed by dysuria and haematuria for up to 48 hours. (B601.9.w9, B602.18.w18)
• Surgical removal of uroliths from the bladder and proximal urethra. (B601.9.w9, J34.24.w3)
  • Perioperative care: Give intravenous fluids for diuresis as well as analgesia and systemic antibiotics. (B602.18.w18)
  • Use cystocentesis (Cystocentesis of Rabbits) to empty the bladder before surgery (manual expression may lead to rupture of the bladder). (B600.14.w14)
  • If calculi are in the urethra, they should be pushed back into the bladder for removal by cystotomy. (B600.14.w14)
    • Use reverse urohydropropulsion to push calculi back to the bladder. (B601.9.w9)
  • See: Cystotomy in Rabbits
• Surgical removal of uroliths from the distal urethra: (B601.9.w9, J513.6.w1)
  • Use a dorso-lateral approach, because the penile urethra is close to the anus. (B601.9.w9)
  • Gently shave the inguinal and scrotal areas, taking care not to damage the thin skin. (J513.6.w1)
  • incise the skin lateral to the penis and dissect through the subcutaneous tissue. (J513.6.w1)
  • Palpate the urolith to choose the appropriate incision site. (J513.6.w1)
  • Incise the penis using a No. 11 scalpel blade. (J513.6.w1)
  • Control any bleeding with cotton swabs. (J513.6.w1)
  • Grasp the urolith with forceps and remove. (J513.6.w1)
  • Close the urethra with 3-0 or 4-0 absorbable suture material (Monocryl) in a simple continuous pattern. ()
  • Close the skin incision with 3-0 nonabsorbable or absorbable suture material in a simple interrupted pattern. (J513.6.w1)
  • OR: 
  • Allow the urethra to heal by second intention, to avoid formation of a stricture. (B601.9.w9)
    • During healing (up to a week), use uretheral catheterisation to empty the bladder; this avoids formation of a fistula. (B601.9.w9)
  • A calculus in one ureter was successfully removed surgically. Stay sutures were placed around the ureter proximal and distal to the calculus, then the ureter was incised longitudinally and the urolith removed. Additional small uroliths were removed from the ureter and ipsilateral kidney by flushing with sterile saline via a 3 French gauge polyurethane cat catheter placed into the proximal ureter. (J8.42.w1)
    • Recovery was uneventful, and the procedure was repeated successfully for a urolith in the contralateral ureter a few months later. (J8.42.w1)
    • Following each procedure, the affected kidney reduced to normal size. (J8.42.w1)
• Nephrotomy or pyelolithotomy:
  • For removal of a calculus in the renal pelvis, if kidney function is thought to be adequate and only minimal damage has occurred to the renal penenchyma. (B602.18.w18) See:
    • Nephrotomy in Rabbits
    • Pyelolithotomy in Rabbits
• Nephrectomy:
  • When a calculus has obstructed the renal pelvis causing hydronephrosis and severe damage to the renal parenchyma. (B602.18.w18)
  • This may be considered if an intravenous excretory pylogram has indicated adequate function of the contralateral kidney. (J513.6.w1)
  • See: Nephrectomy in Rabbits

• If there is a blockage of the urinary tract, catheterisation (Urethral Catheterization in Ferrets) or cystocentesis (Cystocentesis of Ferrets)of the urinary bladder should be performed as soon as possible. (B232.13.w13, B602.4.w4, B629.13.w13, J213.6.w4) 
• Metabolic disturbances must also be corrected as a matter of urgency. (B629.13.w13, J213.6.w4)

Treatment required depends on the location of the calculi and the severity of disease associated with the calculi. (B631.27.w27)

Catheterisation: 

• See Urethral Catheterization in Ferrets
• Note: 
  • Catheterisation is difficult in male ferrets because of the narrow urethra and the os penis. (B602.2.w2, B602.4.w4, J34.28.w1) 
  • A broad spectrum antibiotic should be given and the ferret should be monitored closely with an indwelling catheter. (J34.28.w1)

Cystocentesis:

• Cystocentesis can be used to reduce the filling of the bladder, if catheterisation is not possible. (B629.13.w13, P120.2006.w6) 
• Note: care must be taken not to lacerate the bladder wall. (J34.28.w1)
  • Anaesthesia is advised whilst performing cystocentesis. Using a 25 gauge needle (J34.28.w1) and a 1 mL or 3 mL syringe. (B630.11.w11) 
  • Remove most of the urine, but not all, to protect the bladder against needle trauma. (B602.4.w4)
  • See: Cystocentesis of Ferrets

  Tube cystostomy:

• A temporary tube cystostomy can be used if necessary in a male ferret with severe urethral swelling or damage. Use a 5 to 8 French Foley catheter, placed through the bladder wall. (B602.4.w4, P120.2006.w6) 
  • This can be left in place for up to two weeks if necessary. (P120.2006.w6)

  Retrograde flushing of the urethra

• Once the bladder has been emptied, a catheter can be placed in the urethra. This can be used to flush uroliths into the bladder using sterile saline. (B232.13.w13, B602.4.w4, B629.13.w13, B631.27.w27)

  • Place a catheter partly into the ureter. (B629.13.w13)
  • Pinch the prepuce closed, and use sterile saline to retrograde flush the urethra to dislodge any uroliths back into the bladder. (B629.13.w13)
  • The uroliths can then be removed by cystotomy. (B631.27.w27)
  • See Urethral Catheterization in Ferrets

Cystotomy:

• Once the patient is stable, a cystotomy can be carried out to remove any stones. (B602.4.w4, B629.13.w13, B631.27.w27, J34.17.w4) This procedure is similar to that carried out in cats and dogs. (B602.12.w12)
  • Make a caudal midline abdominal incision in females or a parapreputial incision with a midline abdominal incision in males. (B602.12.w12, B631.23.w23)
    • See: Laparotomy in Ferrets
  • Locate the bladder. (B602.12.w12)
  • Pack the abdomen with moistened sponges. (B602.12.w12)
  • Choose a ventral location on the bladder, away from blood vessels, for the incision line. (B602.12.w12)
  • Place two stay sutures (1.5 metric (4/0 USP) suture material) in the bladder a few cm apart from one another either side of the chosen incision line to exteriorise the bladder. (See: Laparotomy in Ferrets, B631.23.w23)
    • Note: the ferret's urinary bladder is very thin; care should be taken when applying traction. (B602.12.w12)  
  • Incise the bladder. 
    • Have an assistant ready with an aspirator, the tip held ready to take up any urine preventing spillage into the abdomen. (B631.23.w23)
  • Remove any calculi from the bladder. (B602.12.w12, B631.23.w23)
    • Submit calculi for chemical analysis and for culture and sensitivity testing. (B602.12.w12) 
  • Inspect and flush the bladder. (B602.12.w12)  
  • Flush the urethra to check that no calculi remain in the urethra. (B631.23.w23) See Urethral Catheterization in Ferrets 
  • Take a biopsy of the bladder wall for culture and sensitivity. (B602.12.w12)
  • Use 4.0 or 5.0 synthetic absorbable suture material, simple interrupted or simple continuous pattern to close the bladder. (B602.12.w12)
    • Use a simple continuous inverting pattern and 1 metric (5/0 USP) absorbable monofilament suture material. (B631.23.w23)
    • If the bladder wall is thickened, use a simple interrupted pattern. (B631.23.w23)
  • Check for leaks by filling it using sterile saline and a 25 gauge needle. (B602.12.w12, B631.23.w23)
  • If necessary (if leakage occurs) add a continuous inverting suture layer over the other sutures. (B602.12.w12)  
  • Lavage the abdomen. (B602.12.w12)  
  • Close the abdomen. See: Laparotomy in Ferrets. (B602.12.w12)  

• Note: If catheterisation is not possible despite these procedures, it may be necessary to use a temporary tube cystotomy: insert a small Foley catheter through the ventral body wall and into the bladder. (J213.6.w4).

  Perineal urethrostomy:

• If the cystotomy is unsuccessful and in cases of urolithiasis causing urethral obstruction, then a perineal urethrostomy can be performed (B232.13.w13, B602.4.w4, B631.27.w27). This should be caudal to the base of the os penis in males, but proximal to the obstruction. (B629.13.w13, B631.23.w23)
  • Permanent urethrostomy may be required for urethral obstruction secondary to recurrent urethrolithiasis. (B631.23.w23)
  • See: Urethrostomy of Ferrets
   

  Ureterotomy

  • Ureterotomy may be required for the retrieval of unilateral ureteroliths. (B629.13.w13) 
  • This procedure is best carried out with an operating microscope and 0.7 or 0.5 metric (6/0 or 7/0 USP) absorbable suture material. (B631.27.w27)

  Nephrotomy

• Reasons to surgically remove nephroliths include renal pelvic obstruction with obstruction of urine outflow, chronic recurrent urinary tract infections, renal deterioration and if the nephroliths are increasing in size. (B631.27.w27) 
• Note: The surgeon needs to be aware that incising the renal parenchyma will destroy some of the nephrons. Therefore urine production should be measured during and following surgery. (B631.27.w27)

Nephrectomy:

• Nephrectomy can be carried out for treatment of unilateral ureteral or renal pelvic calculi creating an obstruction and hydronephrosis. (B631.27.w27)

Note: Give fluids (J34.17.w4, J34.24.w4) for at least twenty four hours post operatively. (B232.13.w13, B602.4.w4)

• Cystocentesis of Ferrets
• Laparotomy in Ferrets
• Urethrostomy of Ferrets
• Cystocentesis of Rabbits
• Cystotomy in Rabbits
• Nephrectomy in Rabbits
• Nephrotomy in Rabbits
• Pyelolithotomy in Rabbits
• Urethral Catheterization in Ferrets
• Treatment and Care - Surgery

Preventative Measures

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• "Although high dietary calcium intake is not always associated with urinary tract disease, a low calcium intake does appear to prevent the development of sludgy urine and related disorders." However, it is also important to ensure adequate calcium intake to avoid dental disease and metabolic bone disease. (B600.14.w14)
• Feed a diet based on grass hay and green vegetables, with timothy grass-based pellets as a concentrate food. (B601.9.w9, B602.18.w18)
• Do not feed any vitamin/mineral supplement. (B601.9.w9, B602.18.w18)
• Limit intake of calcium rich foods including alfalfa (whether as hay or pellets), and excessive amounts of kale, carrot tops, clover and dandelion. (B601.9.w9)
• Encourage exercise to avoid obesity. (B602.18.w18)

• In the long term, the diet should be changed to one high in animal-based protein (J213.6.w4). A commercial ferret diet is recommended. (B602.4.w4) 
  • This should be done gradually over seven to ten days; provide plenty of water. (B232.13.w13, B629.13.w13)

• Food and Feeding for Mammals
• Preventative Medicine for Mammals

Environmental and Population Control Measures

Lagomorphs

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• Environmental and Population Management - General