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Today's VeTerinary PracTice | september/october 2015 | tvpjournal.com Feline sTruViTe & calcium oxalaTe uroliThiasis Peer reviewed 20 Calcium Oxalate Uroliths Several commercially available diets have been specifcally formulated to prevent recurrence of calcium oxalate uroliths in cats (Table 4, page 19). Canned diets are usually recommended over dry diets because of their high water content. Dietary Restrictions. Moderate restriction of calcium, oxalate, sodium, and potassium intake in association with normal intake of phosphorus and mild increases in magnesium is recommended to prevent recurrence of calcium oxalate uroliths after surgical removal. 17 Increased dietary sodium intake may result in an increase in urinary excretion of calcium and, therefore, should be avoided. Feeding human foods with high calcium or oxalate content (eg, chocolate, peanuts, beets, sweet potatoes, spinach, rhubarb) should also be avoided. Potassium Citrate. Oral potassium citrate may help prevent recurrence of calcium oxalate uroliths 1 ; citrate complexes with calcium, forming the more soluble calcium citrate in urine. In addition, potassium citrate results in mild urine alkalization, which increases the solubility of calcium oxalate. However, avoid overzealous urine alkalization because it may result in formation of calcium phosphate uroliths. Urine alkalization is indicated if urine pH is consistently lower than 6.5. Titrate potassium citrate to produce an ideal target urine pH of 7 to 7.5. The recommended starting dose of potassium citrate is 50 to 75 mg/kg PO Q 12 H. Diuretics. Use of thiazide diuretics to decrease urinary excretion of calcium in cats with recurrent calcium oxalate urolithiasis is controversial. In healthy young female cats, use of hydrochlorothiazide was associated with lower urine calcium oxalate saturation but there was no difference in 24-hour urine calcium excretion. 18 The authors of that study cautioned against extrapolating the results to cats with recurrent calcium oxalate urolithiasis. CKD = chronic kidney disease; SUB = subcutaneous ureteral bypass; UTI = urinary tract infection FIGURE CREDIT Figures 3 to 5 reprinted with permission from Loyd K, Grauer GF. Kidney disease in a cat. Clin Brief 2011; 9:48-52. References 1. Forrester SD, Kruger JM, Allen TA. Feline lower urinary tract diseases. In Hand MS, Thatcher CD, Remillard RL, et al (eds): Small Animal Clinical Nutrition, 5th ed. Topeka, KS: Mark Morris Institute, 2010, pp 925-976. 2. Lekcharoensuk C, Osborne CA, Lulich JP, et al. Association between dietary factors and calcium oxalate and magnesium ammonium phosphate urolithiasis in cats. JAVMA 2001; 219: 1228-1237. 3. Hunprasit V, Lulich JP, Osborne CA, Nwaokorie E. Canine and feline urolith epidemiology: 1981-2013. DVM360 Magazine August 1, 2014. http://veterinarynews.dvm360.com/canine- and-feline-urolith-epidemiology-1981-2013. 4. Barsanti JA, Finco DR, Brown SA. Diseases of the lower urinary tract. In Sherding RG (ed): The Cat: Diseases and Clinical Management, 2nd ed. New York: Churchill Livingstone, 1994, pp 1769-1823. 5. Marquez GA, Klausner JS, Osborne CA. Calcium oxalate urolithiasis in a cat with a functional parathyroid adenocarcinoma. JAVMA 1995; 206:817-819. 6. Kirk CA, Ling GV, Franti CE, et al. Evaluation of factors associated with development of calcium oxalate urolithiasis in cats. JAVMA 207:1429-1434, 1995. 7. Thumchai R, Lulich J, Osborne CA, et al. Epizootiologic evaluation of urolithiasis in cats: 3498 cases (1982-1992). JAVMA 1996; 208:547-551. 8. Lekcharoensuk C, Lulich JP, Osborne CA, et al. Association between patient-related factors and risk of calcium oxalate and magnesium ammonium phosphate urolithiasis in cats. JAVMA 2000; 217:520-525. 9. Houston D, Moore AEP. Canine and feline urolithiasis: Examination of over 50,000 urolith submissions to the Canadian Veterinary Urolith Centre from 1998 to 2008. Can Vet J 2009; 50:1263-1268. 10. Cannon AB, Westropp JL, Ruby AL, Kass PH. Evaluation of trends in urolith composition in cats: 5,230 cases (1985-2004). JAVMA 2007; 231:570-576. 11. Bailiff NL, Westropp JL, Nelson RW, et al. Evaluation of urine specifc gravity and urine sediment as risk factors for urinary tract infections in cats. Vet Clin Pathol 2008; 37:317-322. 12. Albasan H, Osborne CA, Lulich JP, et al. Rate and frequency of recurrence of uroliths after an initial ammonium urate, calcium oxalate, or struvite urolith in cats. JAVMA 2009; 235:1450- 1455. 13. Kyles AE, Hardie EM, Wooden BG, et al. Clinical, clinicopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1984- 2002). JAVMA 2005; 226:932-936. 14. Lulich JP, Kruger JM, MacLeay JM, et al. Effcacy of two commercially available urine-acidifying dry foods for the dissolution of struvite uroliths in cats. JAVMA 2013; 243:1147- 1153. 15. Osborne CA, Lulich JP, Kruger JM, et al. Medical dissolution of feline struvite urocystoliths. JAVMA 1990; 196:1053-1063. 16. Ross SJ, Osborne CA, Lekcharoensuk C, et al. A case-control study of the effects of nephrolithiasis in cats with chronic kidney disease. JAVMA 2007; 230:1854-1859. 17. Lulich JP, Osborne CA, Lekcharoensuk C, et al. Effect of diet on urine composition of cats with calcium oxalate urolithiasis. JAAHA 2004; 40:185-191. 18. Hezel A, Bartges JW, Kirk CA, et al. Infuence of hydrochlorothiazide on urinary calcium oxalate relative supersaturation in healthy young adult female domestic shorthaired cats. Vet Ther 2007; 8:247-254. Gr EGO ry F. GrAUEr Gregory F. Grauer, DVM, MS, Diplomate ACVIM (Small Animal Internal Medicine), is a professor and the Jarvis Chair of Medicine in the Department of Clinical Sciences at Kansas State University College of Veterinary Medicine. Dr. Grauer's clinical and research interests involve the small animal urinary system, and he is on the board of directors of the IRIS and American Society of Veterinary Nephrology and Urology. Dr. Grauer received his postgraduate training in internal medicine at Colorado State University. He has been a faculty member at University of Wisconsin School of Veterinary Medicine and Colorado State University College of Veterinary Medicine.