A cystolith, or bladder stones, can develop in a horse’s bladder when minerals – mainly calcium – accumulate to form a small mass. They can be caused by diet, as forage contains a fair amount of calcium, and can also be related to previous urinary tract infection or kidney damage.
Horses with bladder stones may strain when attempting to urinate, and may also exhibit signs of abdominal pain. Blood in the urine is a common indication of this condition, which is experienced more often by males, because of their long, narrow urethras.
When stones are too large to pass on their own, there are two options – surgery to remove them or, less frequently, laser lithotripsy to break them up so that they can pass during urination.
Dr. Renaud Léguillette, a professor of equine internal medicine at the University of Calgary’s Faculty of Veterinary Medicine, said 99 per cent of horses with bladder stones go for surgery because laser lithotripsy technology is not widely available or because the stone is too large to make this procedure a viable option. With surgery though, there is general anesthetic, increased risks for complications, and healing time is significantly increased. While this is not optimal, it is the usual treatment choice.
The University of Calgary’s Faculty of Veterinary Medicine (UCVM) recently became the first veterinary school to provide community access to laser lithotripsy. Their first patient was Encore, a 16-year-old Hanoverian gelding owned by Lynley Cook, who was referred from Moore Equine in Balzac, Alberta.
Cook has owned Encore since 2006 and competed with him in dressage events all over North America. He has had two previous bladder stone surgeries, which left him out of commission during recovery. Dr. Léguillette said Encore was a good candidate for this less invasive approach as it would allow him to return to training and exercise sooner. He added, “The size of the stone was also at an optimum – about six centimetres in diameter, so it was easier to do the lithotripsy on this medium sized stone rather than a really large one.” Large stones take too long to break up with the laser, so must be surgically removed instead.
Assisting in the procedure was Dr. Serge Chalhoub, a small animal internal medicine specialist and UCVM instructor with significant experience in the advanced use of laser therapy in small animals. He explained that the procedure involves inserting a scope through the urethra and into the bladder. “We break up the bladder stones with a [holmium] laser, through a camera called a cytoscope,” he said. “The horse is not under general anesthesia and stays standing. We use sedatives to keep the horse immobile. The veterinarian sweeps the scope and laser across the surface of the stone to produce a groove until a fragment breaks off. This is repeated as many times as necessary until the remaining pieces of stone are small enough to pass through the urethra. Larger fragments are removed by grasping them with a wire basket through the endoscope and smaller fragments are flushed out.”
In Encore’s case, after about 35 minutes, the team of UCVM and Moore Equine specialists was able to break down the bladder stone and remove all the fragments.
“I am so pleased with the results and the difference it made for Encore,” said Cook. “He went home the next day, and four days out we took our first ride and we were able to get back training. We have been amazed at how easily and quickly he has returned to his full work load.”