Urolith Center: 750,000 Stones & Counting

 Affected dogs can have one or many bladder stones that can be speck sized or up to four inches in diameter. The Minnesota Urolith Center has amassed the world’s largest database of more than 750,000 veterinary samples of uroliths removed from the urinary tracts of dogs and cats. Urolith Center: 750,000 Stones & Counting By Arden Moore For Veterinary Practice News

The Minnesota Urolith Center recently reached a milestone. Since opening in 1981, this center has amassed the world’s largest database of more than 750,000 veterinary samples of uroliths removed from the urinary tracts of dogs and cats.

But Director Carl Osborne, DVM, Ph.D., Dipl. ACVIM, and Co-Director Jody Lulich, DVM, Ph.D., Dipl. ACVIM, did not spend much time celebrating this record-setting total.

This dedicated duo has been far too busy researching innovative and cost-saving alternatives to surgical removal of bladder stones, also known as urinary calculi, in canine (and feline) bladders on the University of Minnesota College of Veterinary Medicine campus in St. Paul.

"We are definitely on a mission," says Dr. Lulich, a professor who is board-certified in internal medicine.

"We are constantly looking into minimally invasive ways to diagnose, remove and prevent urolithiasis. By dissolving stones medically, by using laser lithotripsy and by feeding affected animals special therapeutic diets, we can minimize their discomfort and drastically decrease the surgical cost to their owners."

Osborne, a professor who heads the world's largest center for urinalysis study of dogs and cats, has been studying the causes and pursuing possible cures for urolithiasis since arriving on campus in 1964. 

Mineral Shifts
In the past three decades, he has noticed a shift in the mineral composition of two specific types of uroliths: calcium oxalate uroliths in the bladder and struvite stones (also called magnesium ammonium phosphate) in the urinary tract.

Back in the early 1980s, calcium oxalate was found in only about 5 percent of canine uroliths. Today, the prevalence of calcium oxalate uroliths exceeds 40 percent of all types of stones submitted to this center for analysis. 

Affected dogs can have one or many of these stones that can be speck sized or up to four inches in diameter.

"There are a number of underlying causes of urolithiasis—some of which we know and unfortunately, some of which we still don't know," he says. "There are also several types of stones and we know that each needs to be treated differently. But we have been making steady progress."

Risk factors for the development of uroliths include genetics as well as bacterial infections of the bladder. Breeds predisposed to developing bladder stones include the bichon frise, cavalier King Charles spaniel, dachshund, Dalmatian, English bulldogs, miniature schnauzer, Newfoundland and shih tzu.

Blood in the urine (hematuria) represents one of the most common signs that a dog has bladder stones.

That is because these rock-like mineral deposits rub against and tear the tissue of the bladder wall and cause bleeding. Other signs associated with this condition include:

Vomiting and abdominal pain

• Muscle spasms
• Loss of appetite
• Swollen abdominal area
• Straining to urinate
• Painful and frequent urination

Treatment options include surgery, urohydropropulsion, laser lithotripsy and dietary management.

Alternatives
The surgical procedure—called a cystotomy—involves making an incision through the abdominal wall to remove the stones while a dog is under anesthesia. The stones are sent to a lab for analysis and the dog is placed on antibiotics and special diet during his recovery. This is by far the most expensive treatment option.

When the stones are small enough to pass through the urethra, a veterinarian may opt to perform urohydropropulsion. While the dog is under anesthesia, a veterinarian will insert a urinary catheter, fill the bladder with sterile saline and flush the stones out the urethra by compressing the dog's bladder.

Another non-surgical alternative is laser lithotripsy. This minimally invasive option breaks the stones into minute fragments without damaging the surrounding tissue. A laser fiber is passed through an endoscope with Holmium: YAG laser pulverizing the stones and removing them from the bladder while the dog is under general anesthesia.

A slow-but-steady treatment option is feeding the affected dog a therapeutic diet low in magnesium and protein. Slowly, the ingredients in these special diets dissolve the stones and are designed to reduce the risk of recurrence.

Water, Water Everywhere
Owners are also encouraged to increase their dogs' water consumption by adding water to kibble, serving canned food or providing flavored dilute broths.

"We are learning how to turn on or turn off defective genes or use medications to block off this defective gene," Osborne adds.

For Drs. Osborne and Lulich, their passion for eventually winning the war on canine urolithiasis is also a personal one. Through the years, both have adopted dogs with diagnosed urinary tract issues, often from owners who were unable financially or who lacked the confidence to provide necessary at-home follow-up care to help them recover.

Osborne recalls a special dog he adopted who was about to be euthanized because of recurring bladder stones. Osborne convinced the owner to allow him to adopt Jake, a then-10-year-old Dalmatian. He treated Jake medically and then placed him on a therapeutic diet to prevent the recurrence of stones.

"Jake turned out to be a wonderful dog and he lived three more happy years with me," Osborne says.

Lulich's pets include two owner surrenders: Frazier, a 9-year-old Yorkshire terrier mix, who had formed calcium oxalate crystals in his bladder, and Oliver, a 12-year-old longhaired Chihuahua who has had a recurrence of stones in his kidneys.

"I only get dogs with urinary tract issues," Lulich says. "While some owners find this disease frustrating, I see it as a challenge to fix these dogs and try to help them enjoy normal and healthy lives."

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