Today's Veterinary Practice

MAY-JUN 2014

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May/June 2014 Today's Veterinary Practice 91 URinaLysis in coMPanion aniMaLs PaRT 2: eVaLUaTion of URine cheMisTRy & sediMenT Today's Technician | tvpjournal.com • Ammonium biurate crys- tals are indicative of liver disease or portosystemic shunts in cats and dogs (Figure 15). These crystals and uric acid crystals may be present in dalmatians due to a defect in purine metabolism. • Bilirubin crystals are occa- sionally observed in the urine of healthy dogs, but always represent an abnor- mal finding in cats (Figure 16). In vitro formation of some crystals can occur in refrig- erated samples, while others form as the pH rises in uncov- ered stored samples. Other • Bacteria may be present in urine as the result of infec- tion or contamination. However, small moving particles in the urine can be mistaken for bacteria. Bacterial rods are more easily identified than bacterial cocci. • Yeast may be present due to contamination or infection (less common). • Lipid droplets are round, variably sized, and refractive during fine focusing. They are commonly observed in feline urine samples (Figure 10). • Sperm may be present in urine samples from intact males, or free catch urine samples from recently bred females. n hPf = high power field; LPf = low power field; Rbc = red blood cell; ssa = sulfosalicylic acid; Ua = urinalysis; uPr:cr = urine protein:creatinine ratio; UsG = urine specific gravity; Wbc = white blood cell References 1. stockham s, scott m. Urinary. Fundaments of Veterinary Clinical Pathology, 2nd ed. ames, ia: Blackwell Publishing, 2008, pp 463-473. 2. Chew dJ, diBartola sP. sample handling, preparation, and analysis. Interpretation of Canine and Feline Urinalysis. wilmington, de: ralston Purina, 1998, p 10. 3. osborne Ca, stevens JB. Biochemical analysis of urine: indications, methods, interpretation. Urine sediment: Under the microscope. Urinalysis: A Clinical Guide to Compassionate Patient Care. robinson, Pa: Bayer Corporation, 1999, pp 105-140. Theresa E. Rizzi, DVM, Diplo- mate ACVP (Clinical Pathology), is a clinical associate professor at Okla- homa State University's Center for Veterinary Health Sciences. Her clinical interests include cytaux- zoon infection in cats, hematology, and diagnostic cytology. Dr. Rizzi teaches select classes in the clinical pathology core curriculum. Figure 12. Struvite crystals Figure 13. Calcium oxalate dihydrate crystals Figure 14. Calcium oxalate monohydrate crystals Figure 16. Aggregate of bilirubin crystals Figure 15. Ammonium biurate crystals TabLe 4. significance of casts TYPE OF CAST SIGNIFICANCE Epithelial (renal tubule cells) Fatty (granular, waxy) Renal tubule degeneration and necrosis Erythrocytes hemorrhage involving the kidneys Hyaline Glomerular proteinuria Leukocyte inflammation involving the kidneys TVP_2014-0506_TT_Urinalysis-Part2.indd 91 5/25/2014 7:28:49 PM

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