Twenty years ago, over 90% of the crystals found in the Lower Urinary Tract (Bladder and Urethra) of “straining” cats were struvite (Magnesium Phosphate). The frequent occurrence of problems created by these stones prompted most manufacturers of cat food to modify their diet formulas, aiming at preventing and dissolving these uroliths. This change proved to be very helpful to the general cat population, evidenced by the significant decrease in the incidence of struvites. Now this type of stone constitutes less than 40% of those identified. However, another type of stone is increasingly being identified, Calcium Oxalate. These stones are found more often in the Upper Urinary Tract (Kidney/Ureter). Clinical signs exhibited by cats with this type of stone are often much more vague than those seen with the classic UTI pet, making diagnosis much more difficult. Many cats are asymptomatic and some may show nonspecific signs, such as lethargy, weight loss, anorexia, vomiting, fever, increased thirst and urination. Some cats may have pain in the abdomen or in the region of the kidneys. A diagnostic work up is initiated with a urine analysis, blood work, and radiographs. It may be necessary to obtain further information to confirm the diagnosis, tests which may include ultrasound, MRI, or contrast studies. There are presently no dietary modifications known to effectively dissolve these stones. The only currently accepted treatment is to remove them surgically. Please consult your regular veterinarian for more information.
Jeffrey D. Whall, D.V.M. Fairland Animal Hospital Silver Spring, MD