Feline urolithiasis - DVM
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Feline urolithiasis


Dried solidified blood calculi

Another reported stone type called dried solidified blood calculi (DSB) has been identified only in cats. DSB calculi are submitted to the California laboratory and are reported to occur in various places in the urinary tract, including the upper urinary tract. These DSB calculi are very firm and stone-like but usually do not contain crystalline material. The incidence of DSB calculi in cats seems to be increasing. These calculi are a particular diagnostic challenge. Many of these calculi were not radio-opaque unless they contained a significant portion of CaOx, calcium phosphate or other radiodense mineral. Furthermore, they often are not identified on ultrasonographic examination. If a veterinarian suspects a case, the potential DSB calculi should be submitted both in formalin and without formalin. The calculi submitted in formalin would be used for histopathological studies.

Urate urolithiasis

After CaOx- and struvite-containing uroliths, urate uroliths appear to be the third most-common mineral type submitted to the California laboratory. Although fluctuations in the percentage of struvite and CaOx-containing uroliths have occurred during the past 20 years, the same does not appear to be true for urate uroliths. No differences in gender are found in cats with urate urolithiasis (49 percent females and 51 percent males). Anecdotally, most of these cats did not have any liver disorders. Further data is needed to help elucidate the pathogenesis of urate urolithiasis in cats.

Collection and submission

Whenever a stone is obtained from an animal (either surgically, catheter-assisted, voided or by lithotripsy), it is important to submit for crystallographic analysis in order to properly identify the minerals present. Evaluating trends in feline urolithiasis is important because it may assist veterinarians in determining what, if any, effect current stone prevention strategies, including dietary modifications and drug therapy, are having in cats with urolithiasis. For more information contact the UC-Davis Stone Analysis Laboratory at http://www.vetmed.ucdavis.edu/ or the Minnesota Urolith Center at http://www.cvm.umn.edu/.

Dr. Hoskins is owner of DocuTech Services. He is a diplomate of the American College of Veterinary Internal Medicine with specialities in small animal pediatrics. He can be reached at (225) 955-3252, fax: (214) 242-2200, or e-mail:


Source: DVM360 MAGAZINE,
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