Stones Stones Go Away…Come Again Another Day. No!
World Small Animal Veterinary Association Congress Proceedings, 2019
M. Dunn
Clinical Sciences, Université de Montréal, St. Hyacinthe, QC, Canada

Removal of lower urinary tract urolithiasis is amenable to various interventional approaches depending on the species, sex, type of stone present and stone burden. Considering minimally invasive approaches to stone removal in lieu of surgical cystotomy is recommended.1 Figure 1. An example of a decision making algorithm in the evaluation of a patient with bladder stones. Procedures are considered in order of least to most invasive. (VIN editor: Figure 1 was not provided at the time of publication).

Voiding Urohydropulsion

Allows antegrade removal of bladder stones through the urethra. Recommended for small stones in female cats and dogs but should not be attempted in male cats.2

Under general anesthesia, a urinary catheter is used to fill the bladder with saline (avoid overfilling, estimated bladder capacity 10–15 ml/kg). The urinary catheter is removed, in females, the patient is positioned vertically, males are placed in lateral recumbency. The urinary bladder is palpated, shaken gently, pulled cranially to straighten the urethra. Gentle but steady pressure is applied to the urinary bladder to induce micturition and allow for expulsion of stones.

Percutaneous Cystolithotomy (PCCL)

Urolith removal of any size/number in dogs and cats of any breed, sex and size. This procedure can be considered when uroliths are too large to be removed by urohydropulsion. Under general anesthesia, a urinary catheter is placed and the bladder is filled with saline. A 1–1.5 cm abdominal incision is made over the bladder apex. The bladder apex is exposed, stay sutures are placed and a screw trocar is advanced into the lumen of the bladder following a stab incision. Rigid/flexible cystoscope is inserted through the trocar under continuous saline irrigation. A stone basket passed through the working channel of the cystoscope is used to remove the stones. In males, all or most of the urethra can be examined in an antegrade manner with a flexible cystoscope. Following removal of the trocar, the bladder incision is closed in a standard manner.

Cystoscopy and Intracorporal Lithotripsy

Allows urolith removal in female dogs and cats and some male dogs. Male cats, small male dogs or patients with large stone burdens should undergo PCCL. Under general anesthesia, a retrograde urethrocystoscopy is performed.

Small uroliths are removed using a stone basket. Larger uroliths are fragmented by a holmium:YAG laser or electrohydraulic lithotripter.3 Direct contact of the tip of the laser fiber is required. Once fragments are small enough, they can be removed using the stone retrieval basket. Smaller fragments and debris can also be voided by urohydropulsion.

Figure 2. Summary of minimally invasive options and guidelines for patient selection for the removal of bladder uroliths in dogs and cats


Size and number of uroliths

Sex and species



Voiding urohydropulsion

Stones <3–4 mm in small female dogs
Stones <2.5 mm in female cats
Male dogs limited by size of penile urethra

Female dogs and cats
Not indicated in male cats as risk of urethral obstruction

Low cost equipment
Can be done in general practice

Stones may remain in the bladder
Large and spiculated stones may obstruct the urethra

Percutaneous cystolithotomy (PCCL)

No restrictions

No restrictions

Excellent visualization of the entire lower urinary tract and easy retrograde stone removal

Specialized equipment

Cystoscopic basket retrieval

Access to lithotripsy may be necessary for large or embedded stones

Female dogs and cats
Male dogs >7 kg (penile urethra must allow passage of the flexible scope)

No suture material in the bladder

Specialized equipment

Intracorporal lithotripsy

Low stone burden preferable

Female cats and dogs
Male dogs >7 kg

No suture material in the bladder

Specialized equipment
Long procedural length with large stone burden


1.  Lulich JP, Berent AC, Adams JL, Westropp JW, Bartges JW, Osborne CA. ACVIM Small Animal Consensus Recommendations on the Treatment and Prevention of Uroliths in Dogs and Cats. J Vet Intern Med. 2016;30:1564–1574.

2.  Butty E, Vachon C, Dunn M. Interventional urology. Vet Clin Small Anim. 2019;49:287–309.

3.  Defarges A, Dunn M. Use of electrohydraulic lithotripsy to treat bladder and urethral calculi in 28 dogs. J Vet Intern Med. 2008;22:1267–1273.


Speaker Information
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M. Dunn
Clinical Sciences
Université de Montréal
St. Hyacinthe, QC, Canada