Lasers bring relief to injured dogs

24 Jan 2006

A fiber coupled YAG laser system that can zap bladder stones brings urinary relief to dogs.

Delegates at Photonics West's BiOS session witnessed how lasers are being used to shatter and remove bladder stones from the urinary tract of dogs. Larry Adams from Purdue University, US, has come up with a practical setup based on a holmium YAG laser system that gives a success rate of almost 90%.

Previous attempts at electrohydraulic methods have required bulky equipment, which made them difficult to use. Conveniently, the Purdue University apparatus can be fiber-coupled and passed down the working channel of a standard cystoscope, a thin tube equipped with an eyepiece that is passed into the bladder.

Adams and colleagues from the University of Minnesota enrolled a total of 24 dogs of various breeds onto their initial study and used a 20 W holmium YAG laser emitting 2100 nm pulses.

Each dog was given a general anesthetic before pulses of between 0.5 to 0.7 J at a repetition rate of 5 to 10 Hz were fired at the bladder stone. To help users target the stones, the system was also fitted with a red targeting beam.

"Our aim was to create small fragments before flushing out the bladder," Adams told the audience. "The pulse energy was increased where necessary but did not damage the surrounding tissue. The initial stone size was typically less than 3 cm."

Adams and colleagues reported success in all ten female dogs on the study and added that the laser was used for an average of 30 minutes per dog.

Male dogs however proved more difficult and required around 75 minutes of laser treatment. Here the procedure was judged to have been successful on only 11 out of the 14 (79%) animals based on difficulties in passing the ureteroscope, a tool for examining the bladder, through the narrow urinary tract.

Author
Jacqueline Hewett is technology editor on Optics.org and Opto & Laser Europe magazine.