Urinary calculi (stones) are a common cause of urinary tract obstruction, irritation, and a complicating factor of urinary tract infections in cats and dogs. The majority of calculi are found in the bladder or urethra, however they can also be located in the kidneys and ureters. Depending on the underlying cause of calculi formation, their chemical composition can vary (oxalate, struvite, urate or cystine). While dietary changes and medication may be effective treatments, they are only useful for specific types of calculi. The majority of calculi must be physically removed, especially if they are causing a urinary obstruction. Traditionally, surgery is performed to remove the calculi from the bladder (a procedure known as a cystotomy). Due to the invasive nature of this procedure, incision care is required and recovery time may be prolonged.
CYSTOTOMY: An incision of the urinary bladder wall is made to physically extract calculi. To reach the bladder, the surgeon approaches through the abdominal wall. The image below shows calculi within the bladder.
Lithotripsy, literally meaning ‘breaking of the stone’, is a minimally invasive procedure used to break the calculi into small fragments. Identical to human medicine, lithotripsy can be performed in cats and dogs by applying external shock waves (extracorporeal shock wave lithotripsy) or by using a LASER directly on the calculi to break apart. Shock wave lithotripsy is not as useful for the break down of bladder calculi, but it is occasionally utilized for fragmentation of kidney stones. LASER Lithotripsy, on the other hand, utilizes a Holmium:YAG LASER that ablates calculi via a photothermal process. The LASER energy is strongly absorbed by water, thereby allowing the short LASER pulses to create shock waves that cause calculi fragmentation. This unique property of the LASER makes it safe and effective for disintegrating and removing urinary calculi with little risk of damage to surrounding tissue.
visualization of urinary calculi
LASER Lithotripsy, performed under general anesthesia, requires visualization of the calculus through the urethra with a fiberoptic cystoscope. A LASER fiber is passed through the cystoscope and positioned in contact with the calculus. LASER energy is then applied to break down the calculus material, regardless of its chemical composition, into many small fragments. Once the fragments are small enough, they are extracted via cystoscopic basket and/or voiding hydropulpusion (flushed out through the urethra), thereby completely avoiding the need for a surgical incision to remove the calculi.
Dr. Matt Vaughan, Diplomate ACVIM
The LASER transmits energy through a very short distance making it a safe procedure and allowing urinary calculi fragmentation to occur with minimal risk of damage to surrounding tissue.
LASER Lithotripsy is a minimally invasive procedure performed without an incision. While it is recommended for patients to be monitored overnight after the procedure, overall, patients experience a reduced recovery time.
LASER Lithotripsy is performed under general anesthesia and depending on the size and calculi burden, the procedure may take as long or longer than the traditional surgical approach. For this reason, the best candidates for LASER Lithotripsy are those patients with smaller or fewer calculi.
LASER Lithotripsy is a treatment option for male and female dogs and female cats.
LASER Lithotripsy is NOT possible in male cats due to the small urethral size. Likewise, this procedure may not be possible in small male dogs (<5 kg).
LASER Lithotripsy is more difficult to perform in male dogs due to a combination of anatomical considerations (small urethral diameter and long urethral length) and limitations associated with the cystoscope. Thus, male candidates are best limited to those with a small calculi burden.
LASER Lithotripsy is performed for the fragmentation of bladder calculi. It is not suitable for the fragmentation of calculi in the ureter or kidney.
Each case is evaluated individually to determine whether LASER Lithotripsy
is the best treatment plan.
The LASER is also an ideal tool for other minimally invasive procedures including polyp removal, debulking of urethral tumors and ectopic ureter ablation, a minimally invasive procedure performed through the cystoscope to correct ectopic ureters with a success rate that rivals or surpasses that of traditional surgery.
Seattle Veterinary Specialists is the only veterinary hospital in the greater Puget Sound area to offer LASER Lithotripsy, an advanced and innovative approach, for removal of canine and feline bladder calculi. Dr. Matt Vaughan, Diplomate ACVIM Internal Medicine, is well-versed and adept in several advanced minimally invasive procedures, including LASER Lithotripsy.
For more information or to schedule an appointment for an evaluation, please contact Jeana Brennan, Referral Coordinator for the Internal Medicine service at Seattle Veterinary Specialists at 425.823.9111.