Exotis ISSN 2398-2985

Reptiles

Cystic calculi

Synonym(s): Bladder stones, Urolithiasis, Urinary calculi, Urinary stones

Contributor(s): Mark Naguib, Yvette Rowntree

Introduction

  • Cause: concretions of insoluble urate salts in the urinary bladders of tortoises and in those lizard species that possess a urinary bladder.
  • Signs: lethargy, anorexia, dysuria, tenesmus, hind limb weakness, cloaca organ prolapse, dystocia.
  • Diagnosis: radiography, ultrasonography, cystoscopy.
  • Treatment: removal per cloaca or via surgical coeliotomy and cystotomy. Management changes to prevent recurrence.
  • Prognosis: generally good although dependent on underlying cause.

Pathogenesis

Etiology

  • Concretion of insoluble urate compounds in the urinary bladder.
  • Can be caused by a number of factors listed below.

Predisposing factors

General

  • Excessive dietary protein, particularly in herbivorous species.
  • Excessive oxalate consumption has been proposed.
  • Chronic dehydration is the most common cause.
  • Renal disease Renal disease.
  • Bacterial cystitis.
  • Retropulsed eggs that have entered the urinary bladder may act as a nidus.

Pathophysiology

  • In contrast to mammals, terrestrial reptiles are uricotelic.
  • Uric acid is the main waste product of protein metabolism.
  • Increased uric acid production, eg due to diet, or decreased excretion, eg with renal disease, or chronic dehydration, leads to increased levels of urate monohydrate crystals in the urine .
  • Urate crystals are relatively insoluble and as a result, easily form urate salts which can then form concretions in the urinary bladder.
  • As the size of the calculi increases, they cause inflammation of the bladder wall and discomfort.
  • Some may exert a space occupying effect and interfere with GI function, breathing and locomotion.
  • Anorexia Anorexia and lethargy follow.

Timecourse

  • Usually chronic over many weeks to months but often only noticed once significant lethargy and anorexia or mobility problems become evident.

Epidemiology

  • Disease is often secondary to husbandry therefore more than one animal in the same environment may be affected.

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.
  • Di Girolamo N (2016) Reptile soft tissue surgery. Vet Clin North Am Exotic Anim Pract 19 (1), 97-131 PubMed.
  • Reavill D R & Schmidt R E (2010) Urinary tract diseases of reptiles. J Exotic Pet Med 19 (4), 280-289 VetMedResource.

Other sources of information

  • Doneley B, Monks D, Johnson R & Carmel B Eds (2018) Reptile Medicine and Surgery in Clinical Practice. Wiley-Blackwell, UK.
  • Hochleithner C & Holland M (2014) Ultrasonography. In: Current Therapy in Reptile Medicine and Surgery. Eds: Mader D R & Divers S J. Elsevier Saunders, USA. pp 107-127.
  • Mader D R et al (2006) Surgery. In: Reptile Medicine and Surgery. 2nd edn. Saunders Elsevier, USA. pp 581-630.
  • Johnson J D (2004) Urogenital System. In: BSAVA Manual of Reptiles. Eds: Girling S J & Raiti P. BSAVA, UK. pp 261-272.
  • McArthur S, Wilkinson R & Meyer J (2004) Diagnostic Imaging Techniques. In: Medicine and Surgery of Tortoises and Turtles. Blackwell Publishing, UK. pp 187-238.
  • McArthur S & Hernandez-Divers S (2004) Surgery. In: Medicine and Surgery of Tortoises and Turtles. Blackwell Publishing, UK. pp 403-464.


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