Urolithiasis is a common urinary disorder of dogs characterized by urolith blockage of the urethral tract from the renal pelvis to the distal urethra.
Urolithiasis may be a congenital disease (e.g. hyperuricosuria) or acquired.
Nephroliths, caused by calculi within the renal pelvis or ureter, can result in complete or partial obstruction of the urinary collecting system and subsequently cause hydronephrosis and hydroureter. Complete ureteral obstruction will cause irreversible damage to the renal parenchyma necessitating lifelong management or resulting in death of the patient.
The most common canine uroliths are, in order of importance:
- magnesium ammonium phosphate (struvite)
- Calcium oxalate uroliths
- Cystine uroliths
- Urate uroliths
- Silica uroliths
- Calcium phosphate uroliths
- Xanthine uroliths
- Miscellaneous uroliths - dolomite, tetracycline, sulfonamides
- Foreign bodies - e.g. grass awns, suture material, urinary catheters, hair, bullets, needles
Foreign body uroliths can arrive in the urinary bladder by iatrogenic mechanisms (during surgery or urinary tract instrumentation), by retrograde movement up the urethra, by a transabdominal route (by migration from the skin), or by a transvesical route (by migration from other abdominal structures).
Urinalysis is required to establish the type of urolith, usually requiring reference laboratory analysis.
Use of radiography and ultrasonography is often confirmatory, and passage of a urethral catheter often confirms the presence of uroliths.
If urolithiasis occurs, catheterization of the urethra is required. New techniques for urolith removal include transvesicular percutaneous cystolithotomy.
With severe obstructions, marsupialization of the bladder may be required in the short-term to alleviate urinary obstruction, followed by later recatherization once urethral swelling has subsided. Dantrolene is often used to minimize urethral spasm during the acute phase of recovery.
- Hecht S et al (2010) (99m)Tc-DTPA diuretic renal scintigraphy in dogs with nephroureterolithiasis. Can Vet J 51(12):1360-6
- Andren-Sandberg A (1983) Permanent impairment of renal function demonstrated by renographic follow-up in ureterolithiasis. Scand J Urol Nephrol 17:81–84
- Osborne CA et al (1986) Etiopathogenesis of uncommon canine uroliths. Xanthine, carbonate, drugs, and drug metabolites. Vet Clin North Am Small Anim Pract 16(2):217-225
- Osborne CA et al (1995) Canine and feline urolithiases: Relationship of etiopathogenesis to treatment and prevention. In: Osborne CA, Finco DR, editors. Canine and Feline Nephrology and Urology. Philadelphia: Williams and Wilkins. pp:798–888
- Reimer SB et al (2004) Unusual urethral calculi in 2 male dogs. J Am Anim Hosp Assoc 40:157–161
- Houston DM & Eaglesome H (1999) Unusual case of foreign body-induced struvite urolithiasis in a dog. Can Vet J 40:125–126
- Wyatt KM et al (1999) An enterovesical foreign body in a dog. Aust Vet J 77:27–29
- Snyder DM et al (2005) Diagnosis and surgical management of ureteral calculi in dogs: 16 cases (1990–2003). N Z Vet J 53:19–25
- Hardie EM & Kyles AE (2004) Management of ureteral obstruction. Vet Clin North Am Small Anim Pract 34:989–1010
- Adin CA et al (2003) Antegrade pyelography for suspected ureteral obstruction in cats: 11 cases (1995–2001). J Am Vet Med Assoc 222:1576–1581
- Nyland TG et al (1993) Diagnosis of urinary tract obstruction in dogs using duplex Doppler ultrasonography. Vet Radiol Ultrasound 34:348–352
- Runge JJ et al (2011) Transvesicular percutaneous cystolithotomy for the retrieval of cystic and urethral calculi in dogs and cats: 27 cases (2006-2008). J Am Vet Med Assoc 239(3):344-349