Ureteroliths are a ureteral disease of dogs characterized by urinary crystals (uroliths) located within the urinary system between the renal pelvis and urinary bladder.
However, it is not uncommon for dogs to have nephrolithiasis, ureterolithiasis and urolithiasis. Bilateral ureteroliths also occur but are more rare.
These crystals frequently cause unilateral ureteral obstruction, resulting in retrograde increases in intraureteral pressure with consequent hydroureter, acute renal injury, nephromegaly and death of the affected kidney.
Types of ureteroliths include:
- Calcium oxalate (most common)
- Calcium phosphate
- Struvite, calcium phosphate and calcium oxalate aggregates
Clinical signs are variable, but consistent symptoms include acute abdominal pain, vomiting and depression.
A differential diagnosis would include ectopic ureter, congenital ureteral stenosis, hydronephrosis, ureteral adenocarcinoma and renal parasites (e.g. Dioctophyme renale, Pearsonema plica and Schistosoma japonicum).
Ureteroliths are initially managed medically with intravenous fluid therapy, use of diuretics such as mannitol and prazosin or tamsulosin, but in the majority of cases, surgical intervention is indicated because the time required will result in excessive kidney damage.
Surgical intervention depends on financial constraints and many are managed with ureterectomy or neoureterocystostomy via exploratory laparotomy. Due to the negative effects of urine on wound healing and the risk of uroabdomen, alternative methods of therapy should be considered such as the placing of ureteral stents, extracorporeal shock wave lithotripsy or subcutaneous ureteral bypass.
Placement of double-pigtail ureteral stents could obviate complications associated with ureterectomy such as leakage, structure or re-obstruction. Stents are placed via endoscopy, interventional fluoroscopy or laparotomy. Complications of this procedure include proliferative fibrosis at the ureterovesicular junction, cystitis, dysuria, stent migration and stent occlusion.
Serial monitoring of individual cases is recommended in uncomplicated cases, using diagnostic imaging, hematological testing and treatment with furosemide and intravenous fluids.
Spontaneous retrograde movement of these ureteroliths may occur, with movement anteriorly back into the renal pelvis or passing into the urinary bladder, obviating the need for surgical intervention.
Complications such as ureteral stricture, ureteral stenosis and chronic renal disease are possible in recurrent cases.
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