Treating Bladder and Kidney Stones

When a 7-year-old, 6-pound Yorkshire Terrier named “Sasha” came to Ryan Veterinary Hospital in 2006 from Florida for treatment of a very large kidney stone, her owners were relieved there was a minimally invasive treatment option. Sasha’s veterinarian in Florida discovered the dog’s kidney values were not normal after blood work was performed for a teeth cleaning and referred the dog to the University of Pennsylvania for the minimally invasive treatment.

Berent and Weisse, along with Bagley and Solomon, were part of the veterinary team that used interventional techniques — fluoroscopy, percutaneous nephrolithotomy and ureteral stenting — to diagnose and then help break up a 2 ½-centimeter stone obstructing Sasha’s kidney directly through her skin. The endoscope was placed through her skin and into her kidney through a very small hole for removal of the stone with lithotripsy.

The case was notable because it was the first time this procedure was performed clinically in a dog patient. After the procedure a stent was used to protect the ureter and eliminate any post-procedural complications. The procedure, with its many steps, resulted in successfully breaking and removing the stone.

Another toy dog, a mixed terrier named “Meesha,” also had a very large stone, but this time the veterinarians elected to use shock wave lithotripsy to fragment the pieces and then let them pass down the ureter on their own with a ureteral stent in place to protect the ureter. The stent was placed using endsocopy, and no surgery was necessary. Extracorporeal shock wave lithotripsy (ESWL) uses high-energy shock waves to pinpoint and shatter kidney stones into a fine powder and thus break stones with fluoroscopy guidance rather than surgery.

“In Sasha’s case, it was a significantly large kidney stone for the little dog,” says Berent. “We went right through the kidney and treated Sasha in a method similar to how children and adults with stones are treated. What typically would have been a high-risk, invasive veterinary surgery was achieved in an outpatient procedure, which helped to reduce potential complications from scar tissue or leakage. The procedure immediately relieved Sasha’s pain. This was similarly the case for Meesha, though performed in a different manner.”

Bladder and kidney stones are common in small terriers and toy breeds, Berent says. Affected breeds include Bichon Frise, Maltese, Chihuahua, Lhasa Apso, Miniature Poodle, Pom­eranian, Cairn Terrier and Yorkshire Terrier. Often dogs are in pain due to the obstruction. Many cannot urinate easily, and blood may be in the urine. Dogs may have stones from two days to two months before their condition becomes urgent.

Most bladder stones in toy dogs are calcium oxalate stones. These stones sometimes form due to lack of certain substances, like nephrocalcin and others, in their urine that naturally inhibit their formation. As with kidney stones, bladder stones can be treated using interventional radiology.

“We can go in with a scope and see the stone,” Berent explains. “We then put a laser fiber through a cystoscope and direct it onto the bladder stone. When the stone comes in contact with the laser, the energy fragments the stone until the pieces are small enough for removing.

“Over 90 percent of the time we can get stones to pass. Patients are able to go home the same day, which also helps to reduce the cost versus conventional surgery.”

While interventional radiology has been used to treat humans for decades, the procedures are new in veterinary medicine. Successful results promise that they are likely to be used even more in the future.

This article originally appeared in Today's Breeder, A Nestlé Purina Publication Dedicated to the Needs of Canine Enthusiasts