Equis ISSN 2398-2977

Bladder: calculi

Synonym(s): Urolithiasis, cystolithiasis

Contributor(s): Vetstream Ltd

Introduction

  • Uncommon, but an important cause of obstructive urinary tract disease.
  • Cause: crystal formation around a nucleus.
  • Signs: pollakiuria, hematuria, frequent posturing to urinate; colic.
  • Diagnosis: rectal palpation, cystoscopy, ultrasonography.
  • Treatment: manual extraction; surgical extraction.
  • Prognosis: good with prompt management; recurrence common.

Pathogenesis

Etiology

  • Unclear - little is known about the formation of urinary calculi in the horse.
  • Infection is usually a secondary problem, but damage to the bladder epithelium as a result of cystitis could allow the retention of organic matter that acts as a nidus for crystal adherence.

Suggested factors

  • Urine retention.
  • Hypovitaminosis A.
  • Hypervitaminosis D.
  • Inhibitors or promotors of crystal growth.

Pathophysiology

  • Horses naturally excrete large amounts of calcium carbonate crystals in urine. Urine pH is alkaline, which promotes formation of calcite crystals. Crystals (CaCO3 mainly; phosphate, Mg and NH4 occasionally present) build around a stable nucleus of epithelial cells or mucus in the presence of supersaturated urine.
  • Enlargement of the calculus occurs due to a combination of aggregation of crystals to the surface and precipitation of crystals as cement on the surface.
  • Although equine urine is theoretically an ideal medium for calculus formation urolithiasis does not have a high prevalence.
  • Calculi vary in size from 1.5-20 cm diameter. Type 1 calculi (majority of calculi in horses >90%) are soft, yellow-green, spiculated stones made up of hydrated CaCO3 crystals and easily fragmented. The abrasive spicules cause traumatic cystitis. Type 2 calculi are firm, white, smooth and made up from a mix of calcium, MgCO3 and phosphate ions are difficult to crumble.
  • Acute and complete obstruction can result in bladder rupture and uroperitoneum   Abdomen: uroperitoneum  .

Timecourse

  • Time taken for calculi to develop is not know.

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 VetMedResourse.
  • Reichelt U & Lischer C (2013)Complications associated with transurethral endoscopic-assisted electrohydraulic lithotripsy for treatment of a bladder calculus in a gelding.Equine Vet Educ25(2), 55-59 VetMedResource.
  • Hawkins J F (2013)Surgical treatment of urolithiasis in male horses.Equine Vet Educ25(2), 60-62 VetMedResource.
  • Cripwell D & Coomer R (2012)Cystic calculus in a gelding.UK Vet17(8), 4-8 VetMedResource.
  • Rocken M, Furst Aet al(2012)Endoscopic-assisted electrohydraulic shockwave lithotripsy in standing sedated horses.Vet Surg41(5), 620-624 PubMed.
  • Russell T & Pollock P (2012)Local anaesthesia and hydro-distension to facilitate cystic calculus removal in horses.Vet Surg41(5), 638-642 PubMed.
  • Edwards B & Archer D (2011)Diagnosis and treatment of urolithiasis in horses.In Pract33(1), 2-10 VetMedResource.
  • Duesterdieck-Zellmer K F (2007)Equine Urolithiasis.Vet Clin N Am Eq Pract23(3), 613-629 PubMed.
  • Textor J A, Slone D E & Clark C K (2005)Cystolithiasis secondary to intravesical foreign body in a horse.Vet Rec156(1), 24-26 PubMed.
  • De Jaeger E, De Keersmaecker S & Hannes C (2000)Cystic urolithiasis in horses.Equine Vet Educ12(1), 20-23 VetMedResource.

Other sources of information

  • Jackman D R & Schott II H C (1997)Dysuria.In:Current Therapy in Equine Medicine 4.Ed: Robinson N E. ISBN: 0-7216-2633-5.


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