Veterinary Medicine - October 2008 - (Page 548)

Urolithiasis PEER-REVIEWED passage of uroliths. The development of percutaneous approaches has improved accessibility to sites such as the renal pelvis (percutaneous nephrolithotomy), allowing ultrasonic and laser lithotripsy to be performed with less damage to the surrounding tissues. Although most of these techniques have limited availability at veterinary facilities, continued success in treating uroliths with these minimally invasive methods should increase their availability to veterinary patients in the coming years. Antegrade and retrograde urethral urohydropropulsion in male dogs or cats* After establishing the presence of a urethrolith, perform cystocentesis to decompress the bladder, saving urine for urinalysis and bacterial culture and antimicrobial sensitivity testing. Do not empty the bladder completely during decompression to protect the bladder wall from trauma caused by the tip of the cystocentesis needle. If needed, sedate or anesthetize the patient. Lubricate the area of the urethra adjacent to the obstruction with a 1:1 mixture of physiologic saline solution and sterile aqueous lubricant placed into the urethra through a urinary catheter. If patient size permits, use digital palpation through the rectal wall to attempt to dislodge the urethral urolith. If the urolith is inadequately dislodged, apply pressure to the pelvic urethra with a gloved ﬁnger inserted into the rectum. Inject sterile saline solution through a urinary catheter placed in the penile urethra while compressing the distal penile urethra around the catheter. When notable urethral dilation can be detected by the gloved ﬁnger in the rectum, release the pressure applied to the distal penile urethra while continuing to inject saline solution and applying pressure to the pelvic urethra. The injected saline solution should emerge forcibly antegrade through the urethral oriﬁce and may carry the urolith with it. More commonly, retrograde urohydropropulsion is used to dislodge urethroliths. In this technique, the pressure applied rectally to the distended pelvic urethra is released while continuing to inject saline solution through the urethral catheter and applying pressure to the distal penile urethra around the catheter. The injected saline solution should move forcibly into the bladder, carrying the urethrolith with it. Repeat the described techniques as needed to propulse all the urethroliths either antegrade or retrograde, decompressing the bladder when necessary to relieve pressure.1 *An assistant is required to perform the rectal portions of the procedures described. Identify urolith composition and bacteria Because urolith composition is an important factor in determining the treatment and prevention options, it is important to accurately identify urolith composition whenever possible. The most direct method of determining urolith composition is analyzing the urolith itself. Uroliths can be collected for submission through surgical intervention, routine voiding, voiding urohydropropulsion, or catheter-assisted retrieval. (For more information on this technique, see the boxed text titled “Catheter-assisted urolith retrieval” on page 558.) Analysis can be either qualitative or quantitative. Qualitative analysis is performed by several laboratories and can determine the approximate urolith composition. Quantitative analysis uses more sophisticated techniques to determine the exact composition of the urolith’s nidus (nucleus), body, and shell, including the exact percentages of mixed components. Quantitative analysis is the preferred method for determining urolith composition because it provides a much more accurate analysis when compared with qualitative methods and greater guidance in developing appropriate therapeutic and preventive plans.18 For best results, submit the entire urolith in a dry, unbreakable container. If the patient has multiple uroliths, submit either all the uroliths recovered or a representative assortment for quantitative analysis. Urolith fragments may REFERENCE 1. Osborne CA, Lulich JP, Polzin DJ. Canine retrograde urohydropropulsion: lessons from 25 years of experience. Vet Clin North Am Small Anim Pract 1999;29(1):267-281. be collected for quantitative analysis after lithotripsy by using stone baskets or grasping instruments at the time of the procedure or by collecting voided urine after the procedure and pouring it through a tea strainer. The Minnesota Urolith Center at the University of Minnesota College of Veterinary Medicine will perform quantitative analysis of uroliths at no charge except for standard shipping fees. Submission forms and information can be obtained at http:/ / www.cvm.umn.edu/depts/minnesota urolithcenter/howtosubmitsamples/ home.html. Quantitative analysis can also be performed for a fee at the Urinary Stone Analysis Laboratory at the University of California at Davis School of Veterinary Medicine or at human laboratories such as the Urolithiasis Laboratory at the Baylor College of Medicine in Houston or the Louis C. Herring and Company laboratory in Orlando, Fla. Submitting or saving a recovered urolith, including the nidus, for bacterial culture is recommended in cases in which results of a urine culture are negative or pending, especially in dogs suspected of having struvite uroliths. Submit an entire urolith for bacterial culture in a dry, clean container. Refrigeration is not required for storage or shipping, but, as with all cultures, the specimen should be cultured as soon as possible for optimal results. Antibiotic treatment 548 October 2008 VETERINARY MEDICINE http://www.cvm.umn.edu/depts/minnesotaurolithcenter/howtosubmitsamples/home.html http://www.cvm.umn.edu/depts/minnesotaurolithcenter/howtosubmitsamples/home.html http://www.cvm.umn.edu/depts/minnesotaurolithcenter/howtosubmitsamples/home.html http://www.cvm.umn.edu/depts/minnesotaurolithcenter/howtosubmitsamples/home.html

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Veterinary Medicine - October 2008 Contents Leading Off Clinical Exposures Idea Exchange Stalking Stones Vaginitis in Dogs CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - October 2008

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