Canis ISSN: 2398-2942

Urolithiasis

Synonym(s): Bladder stones, Cystic calculi, Ureteral calculi, Nephroliths

Contributor(s): Phil Nicholls, Melissa Wallace

Introduction

  • Urolithiasis refers to the presence of stones anywhere in the urinary tract.
  • Most canine uroliths are found in the lower urinary tract.
  • Most common types: struvite (magnesium ammonium phosphate), calcium oxalate, cystine and ammonium urate.
  • Rarer types: calcium phosphate, silica, carbonate, xanthine and drugs or their metabolites.
  • Incidence estimated at 0.3-2.8%.
  • Cause: (and therefore treatment) depends on type of urolith; usually due to underlying inherited, congenital or acquired metabolic disorder or infection.
  • Signs: usually of lower urinary tract disease (may be none).
  • Prognosis: many uroliths recur unless underlying cause is corrected, eg infection.
    Print off the owner factsheet on Bladder and kidney stones Bladder and kidney stones to give to your client.
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Pathogenesis

Etiology

  • Supersaturation of urine with crystalloid → crystal nidus (nucleus) formation.

Predisposing factors

General
  • Urine pH.
  • Diet.
  • Metabolic acidosis or alkalosis Acid base imbalance.
  • Medication.
  • Anatomical abnormalities.
  • Lifestyle.
  • Gender.
  • Sedentary lifestyle.

Specific

  • Breed.

Pathophysiology

  • Inherited, congenital or acquired predisposing condition; depends on nature of urolith.
  • Supersaturation of urine with calculogenic crystalloids.

Struvite
  • Approximately 50% of uroliths Urinalysis struvite crystal Urinalysis struvite stonesUrolithiasis: struvite stone Urolithiasis: struvite stone 2 Urolithiasis: struvite and calcium phosphate stone Urolithiasis: struvite and calcium phosphate stones Urolithiasis: calcium phosphate and struvite stone.
  • Oversaturation of urine with magnesium ammonium phosphate.
  • Urinary tract infection with urease-synthesizing bacteria → hydrolysis of urea → ammonia and carbon dioxide → alkaline urine.
  • Other factors: alkaline urine, high protein diet, genetic predisposition.
Calcium oxalate
  • Approximately 30% of uroliths Urinalysis calcium oxalate crystal Urolithiasis: calcium oxalate stones Urolithiasis: calcium oxalate stones 2.
  • Hypercalciuria and/or hyperoxaluria.
  • Causes of hypercalciuria:
    • Intestinal hyperabsorption of calcium.
    • Decreased renal absorption.
    • Hypercalcemia Hypercalcemia: overview , eg hyperparathyroidism, paraneoplastic.

    Cystine
  • Approximately 1% of uroliths Urinalysis cysteine crystal Urinalysis cysteine urolith Urolithiasis: cystine stones.
  • Metabolic defect → increased urinary excretion of cystine, lysine, arginine and ornithine.
  • Acidic urine → precipitation of cystine.
    Urate
  • Approximately 8% of uroliths Urinalysis urate crystals Urinalysis urate urolith Urolithiasis: ammonium urate and uric acid stones.
  • Dalmatian → defect in hepatic uric acid metabolism → increased urinary urate excretion.
  • Other breeds: hepatic dysfunction or portal vessel anomalies → decreased urate metabolism.

Timecourse

  • Uroliths may not be detected until dog is middle-aged.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Hoppe A & Denneberg T (2001) Cystinuria in the dog - clinical studies during 14 years of medical treatment. J Vet Intern Med 15 (4), 361-367 PubMed.
  • Caywood D D & Osborne C A (1986) Surgical removal of canine uroliths. Vet Clin North Am Small Anim Pract 16 (2), 389-407 PubMed.
  • Osborne C A & Polzin D J (1986) Non-surgical management of canine obstructive urolithopathy. Vet Clin North Am Small Anim Pract 16 (2), 333-347 PubMed.
  • Osborne C A, Klausner J S, Krawiec D R et al (1981) Canine struvite urolithiasis - problems and their dissolution. JAVMA 179 (3), 239-244 PubMed.

Other sources of information

  • Osborne C A, Lulich J P, Barges J W (eds) (1999)The Rocket Science of Canine Urolithiasis.The Vet Clin North Am Small Anim Pract29(1), 1-306.
  • Davies M (1996)Management of Canine and Feline Urolithiasis.In:BSAVA Manual of Canine and Feline Nephrology and Urology.Bainbridge J & Elliot J (eds). Chapter 17. pp 209.
  • Ling G V & Sorenson J L (1995)Management and prevention of urate uroliths. In:Current Veterinary Therapy XII. Kirk (ed) W B Saunders, Philadelphia. pp 985-998.
  • Lulich J P & Osbourne C A (1995)Canine calcium oxalateuroliths. In:Current Veterinary Therapy XII. Kirk (ed) W B Saunders, Philadelphia. pp 992-996.
  • Hope A (1994)Canine Lower Urinary Tract Disease.In:Waltham Book of Clinical Nutrition of the dog and cat.Chapter 19. pp 335. (Very useful overview.)
  • Osborne C A, Lulich J P, Bartges J W, Thumchai R, Felice L J, Unger L K, Koehler L A, Bird K A & Swanson L (1994)Canine urolithiasis - diagnosis, treatment and prevention.In:Renal Disease in Small Animal Practice.Trenton, NJ: Veterinary Learning Systems. pp 133-150. ISBN 1 884254 18 7 (Useful tables and flow diagrams).


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