Veterinary Medicine - October 2008 - (Page 554)

Urolithiasis PEER-REVIEWED TABLE 2 (continued) Composition Cystine Crystal or Urolith Characteristics • Crystal—large, ﬂat, hexagonal • Urolith—small; spherical; light-yellow, light-brown, or light-green; relatively radiolucent Predisposing Factors • Inherited metabolic disorder of the renal tubules • Acid urine Treatment* • Removal** or lithotripsy • Medical dissolution in dogs: Feed a diet formulated for managing cystine stones and thiol disulﬁde exchange drug. Silicate • Crystal—amorphous silica, no distinct shape • Urolith—most often have jackstone appearance; grayish-white to brown; radiopaque May be diet-related, especially diets high in corn gluten or rice and soybean hulls Removal** or lithotripsy Dried solidiﬁed blood Usually formed from organic material and contains no crystalline elements; radiolucent Idiopathic Removal** *Treatment and prevention plans for all uroliths should include increasing the patient’s water intake. **Removal refers to surgical removal or voiding urohydropropulsion. Pet Nutrition) should not be fed for longer than six months. The nutrient restrictions, fat content, and increased sodium content of s/d make it unsuitable as a diet for puppies or kittens, pregnant or lactating pets, and pets with heart failure, hypertension, or renal failure. In a recent study in which the results are unpublished, an alternative protocol for treating infection-related struvite urocystoliths in a small number of dogs has preliminarily shown dissolution of these uroliths by feeding a maintenance, noncalculolytic diet (e.g. Science Diet Adult Original [Hill’s Pet Nutrition], Dog Chow [Purina]) combined with antibiotic therapy and the urinary acidi er d,l-methionine (Methio-Form—Vet-A-Mix; 100 mg/kg orally twice a day).26 This alternative protocol is still under evaluation but could be considered for treating struvite urocystoliths in dogs that refuse to eat the specially formulated calculolytic diets. Failure to dissolve struvite uroliths with an appropriate therapeutic regimen and owner compliance may indicate that the targeted uroliths are not composed of struvite or have layers containing greater than 20% nonstruvite minerals.24,28 Calcium phosphate and calcium carbonate phosphate are occasionally associated with struvite uroliths and may interfere with medical dissolution therapy. Not all patients with suspected or conrmed struvite uroliths are candidates for medical dissolution because of noncompliant owners, complicating health circumstances (e.g. hypertension), or ureteral or urethral uroliths. Surgical removal, lithotripsy, or voiding urohydropropulsion should be considered in these patients depending on the circumstances. Prevention. Prevent sterile struvite uroliths by having owners feed their pets one of the many available diets that increase urine volume, decrease urine pH to < 6.8, and decrease excretion of magnesium, ammonium, and phosphorus (Table 1). In struvite prevention programs in which patient obesity is a concern, canine and feline Prescription Diet w/d (Hill’s Pet Nutrition) can be used. Preventive diets for sterile struvite uroliths are less restrictive than the calculolytic diets but should not be given to puppies or kittens, pregnant or lactating patients, or dogs at risk for pancreatitis. Although these diets can be fed to patients with infection-related struvite 554 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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