This document provides information on urine examination and urinalysis. It discusses sample collection methods including free catch, urethral catheterization, and cystocentesis. Physical examination of the urine includes analyzing color, clarity, odor, specific gravity, pH, protein, glucose, and other substances. A urine sediment examination evaluates for red blood cells, white blood cells, epithelial cells, casts, crystals, and infectious organisms. Specific gravity ranges are provided for cats, dogs, and cattle. Quality control and microscope calibration are also addressed. The procedure for urine sediment analysis is outlined, and example results for certain parasites are described.
9. Specific gravity is defined as the ratio of the weight of
a volume of liquid to the weight of an equal volume of
distilled water
The urine specific gravity (SG) is determined using a
refractometer designed for veterinary samples
Cat= 1.015 to 1.050
Dog= 1.015 to 1.040
Cattle= 1.030–1.045
Specific gravity
10. The saline should be clear and free of any visible
contamination.
The microscope should have been calibrated within
the last 12 months, and the objectives and oculars
used for the calibration procedure should be used for
all measurements on the microscope. Calibration
factors should be pasted in front of or on the body of
the microscope.
QUALITY CONTROL
11. If a 24 hour urine sample was collected, allow the
specimen to sediment for 2 hours, and decant the
major portion of the supernatant. There may be 100
to 200 ml of sediment left. If a first voided urine
specimen is recieved, use the entire specimen.
Place the remaining urine specimen (sediment) in
centrifuge tubes.
Centrifuge the specimen at 500 x g for 5 min
PROCEDURE
12. Decant the supernatant fluid
With a pipette, mix and aspirate the sediment
Place a drop of the sediment on a microscope slide
Place a cover glass on top of the sediment
Observe the specimen under the cover glass at
magnifications of x100 and x400. Examine the entire
coverslip at x100 and at least half the coverslip at
x400
13. trichomoniasis = motlie flagellates are seen
schistosoma haematobium = Eggs(eggs for flame
activity (motile cilia) or live miracidia)
D. renalae= eggs
Stephanurus dentatus = eggs
Results
14. Urine pH is typically acidic in dogs and cats and
alkaline in horses and ruminants, but varies
depending on diet, medications, or presence of
disease.
Urine pH
Microscopic examination of urine sediment should be part of a routine urinalysis. For centrifugation, 3–5 mL of urine is transferred to a conical centrifuge tube. Urine is centrifuged at 1,000–1,500 rpm for ~3–5 min. The supernatant is decanted, leaving ~0.5 mL of urine and sediment in the tip of the conical tube. The sediment is resuspended by tapping the tip of the conical tube against the table several times. A few drops of the sediment are transferred to a glass slide, and a cover slip is applied. Examination of unstained urine is recommended for routine samples. Microscopic examination is performed at 100× (for crystals, casts, and cells) and 400× (for cells and bacteria) magnifications. Contrast of the sample is enhanced by closing the iris diaphragm and lowering the condenser of the microscope. Stains such as Sedistain® and new methylene blue can be used to aid in cell identification but may dilute the specimen and introduce artifacts such as stain precipitate and crystals. Use of a modified Wright stain increases the sensitivity, specificity, and positive and negative predictive values for detection of bacteria. For some tests, air dried, stained smears are necessary.