Veterinary Medicine - October 2008 - (Page 542)

PEER-REVIEWED Stalking stones: An overview of canine and feline urolithiasis Did you know that a new type of urolith has been found in cats? Should you institute preventive therapy if you identify only crystalluria? Is antibiotic therapy automatically warranted in animals with indwelling urinary catheters? This internist revamps your knowledge on diagnosing, treating, and preventing urolithiasis. Mary Bowles, DVM, DACVIM U rolithiasis is common in dogs and cats, causing morbidity and, occasionally, mortality. Although renal and ureteral uroliths can sometimes be more dif cult to manage, uroliths can usually be successfully treated medically or surgically or by performing lithotripsy. Longterm success is possible. This article will help you diagnose urolithiasis, determine the urolith composition, and develop an appropriate treatment and prevention plan. same signs may be observed, with the possible addition of blood dripping from the prepuce or vulva independent of urination. Urethral obstruction may result in unsuccessful micturition attempts, lethargy, anorexia, vomiting, abdominal distention, or pain. Ureteroliths and nephroliths may be associated with hematuria and abdominal pain as well as lethargy, fever, decreased appetite, and vomiting if an upper urinary tract infection or obstruction is involved. enhance crystal formation and cause misinterpretation of the urinalysis results.1 Physical examination You may identify a rm object in the bladder during abdominal palpation or nd very small uroliths in voided urine or in penile or vulvar mucoid discharge. Rectal examination ndings may reveal rm objects in the pelvic urethra. Imaging In most cases, de nitively diagnosing urolithiasis requires ultrasonography, survey abdominal or urethral radiography, or contrast radiography. Obtain survey images of the entire length of the urinary tract to identify whether uroliths are present in multiple locations and to identify any factors predisposing the patient to urolith formation, such as infection or neoplasia. Determining the exact number of uroliths with any of the imaging modalities can be challenging in some cases. Ultrasonography is a good initial imaging tool to detect uroliths; however, it does not reveal the radiodensity or shape of uroliths. In addition, unless a patient’s size allows for the use of a rectal transducer, the pelvic urethra cannot be seen with ultrasonography. Survey radiography can reveal the radiodensity and approximate size and contour of uroliths. It is also generally the most cost-effective and available noninvasive procedure for initially evaluating uroliths. Although high-frequency (5 to 7.5 MHz) ultrasonography compared favorContinued on page 543. CLINICAL SIGNS Uroliths in small animals occur most frequently in the bladder (urocystolith) but can also be found in the urethra (urethrolith), ureters (ureterolith), and kidneys (nephrolith). Clinical signs of urolithiasis vary according to the urolith’s location and any underlying or predisposing conditions. In addition, some uroliths do not produce clinical signs and may be discovered incidentally. Since the bladder is the most common site for uroliths, the most frequent clinical signs observed are dysuria, hematuria, and pollakiuria with or without inappropriate urination. If the urethra contains uroliths, the Mary Bowles, DVM, DACVIM Department of Veterinary Clinical Sciences Center for Veterinary Health Sciences Oklahoma State University Stillwater, OK 74078 DIAGNOSIS OVERVIEW Urolithiasis diagnosis may be aided by historical information, such as a previous occurrence of urolithiasis or an owner’s observation of signs compatible with uroliths. A predisposition to urolithiasis may be indicated by patient signalment or pre-existing medical conditions favoring urolith formation. Routine laboratory test (complete blood count, serum chemistry pro le, urinalysis) results do not speci cally detect uroliths but provide valuable information about predisposing or complicating medical conditions. Urinalysis Urinalysis ndings, including the pH, evidence of bacterial infection, and the presence of speci c crystal types may indicate urolith composition. Urinalysis is best performed within 30 minutes of sample collection. Refrigeration helps preserve the urine sample but can alter the chemical and sediment ndings. In particular, time and refrigeration lead to pH and temperature changes, which 542 October 2008 VETERINARY MEDICINE

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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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