2. Packed Cell Volume (PCV)
2
Percentage of whole blood composed of RBCs
Microhematocrit tubes
Red ring – heparinized
Blue ring – not treated
3. Packed Cell Volume
3
RBC – high specific gravity
Dark red layer
Buffy coat
Whitish-gray layer above the RBC layer
Consists of WBCs and platelets
Height – rough estimate of total WBC count
Plasma
Clear to pale yellow fluid
Top layer
4. Packed Cell Volume
4
Plasma layer
Normal – clear to pale yellow
Cloudy – lipemic
Reddish tinge – hemolyzed
Deep yellow – icteric
5. Packed Cell Volume
5
Significance of results
Pathologic condition
Below normal
Anemia
Inadequate volume of blood to anticoagulant ratio
Above normal
Polycythemia
Dehydrated
7. Plasma Protein Concentration/Total Protein
Lipemic plasma contains chylomicrons that cause
the light to diffract in many different directions and
usually results in a false increase in the total protein
reading.
Most often, increased PCV is seen in patients who
are dehydrated, as a result of the lower volume of
fluid present in the vasculature.
PCV will also be falsely decreased in an inadequate
volume of blood was collected into the anticoagulant.
8. Physical properties
Include those made without a microscope
or chemical reagents
Volume
Color
Odor
Transparency
Specific gravity
8
Routine Analysis
9. Owners may confuse:
Pollakiuria – frequent urination
Polyuria – increased production
Many factors involved
Fluid intake, external losses, temperature and humidity,
amount and type of food, activity level, size of animal
and species
Cannot evaluate on one urination
Need 24-hour urine volume collection
Valuable but not practical
May need to observe in cage or outdoors to get an estimate
9
Urine Volume
11. Normal
Light yellow to amber
Pigments = urochromes
Darker yellow = more concentrated urine
Higher specific gravity
Lighter color = less concentrated
Lower specific gravity
Yellow-brown or green
Contain bile pigments
Red or brownish
Presence of RBCs (hematuria) or hemoglobin (hemoglobinuria)
Due to muscle cell lysis
Some drugs affect urine color
Place against a white background for proper evaluation
11
Color
13. In most species:
Clear or transparent
Equine normally cloudy and rabbits
normally milky
High concentration of calcium
carbonate crystals and mucus
Observe against a letter print background
Noted as clear, slightly cloudy, cloudy, or
turbid (flocculent)
13
Clarity or Transparency
14. Not a highly diagnostic evaluation but
helpful
Species have distinctive odors
An ammonia may occur with
Cystitis
Bacteria that produce urease metabolize urea to ammonia
A sample left standing too long
Sweet or fruity odor
Ketones
Diabetes mellitus
Ketosis in cows
Pregnancy in ewes
14
Odor
15. Weight (density) of a quantity of liquid
compared with that of an equal amount of
distilled water
The number and molecular weight of
dissolved solutes determine the SG of
urine
Can be measured before or after
centrifuging
Particles that settle have no effect on SG
15
Specific Gravity
17. Processed by a variety of techniques
Impression smears
Compression or modified compression
preparations
Line smears
Starfish smears
Wedge smears
Type of preparation depends on characteristics
of the sample
17
Cytology Samples
18. Compression preparation
Squash prep
Can yield excellent cytologic smears
Expel contents of aspirate onto the middle of slide
Gently place a second slide at right angles to the first
slide
The spreader slide is quickly and smoothly slid across the
prep slide
Downward pressure should not be placed on the spreader
slide
Excessive cell rupturing
Modification
Rotate second slide 45 degrees and lift upward
18
Smear Preparation
20. Drags the aspirate peripherally in several directions
with the point of a needle
Tends not to damage cells, but leaves a thick layer
Ideal for viscous
samples
20
Starfish Smear
21. Dermatophytes
More than 3 dozen different organisms in taxonomic
genera
Microsporum and Trichophyton spp.
Most commonly seen
M. canis, M. gypseum, and T. mentagrophytes
Also classified by habitat
Anthropophilic – confined to humans
Zoophilic – parasites of animals
Geophilic – free-living saprophytes in soil
21
22. Dermatophyte Testing
Most dermatophytes will grow on the hair shaft and
some can be visualized microscopically
Pluck a few hairs – periphery lesion
Place on a slide with 1 to 2 drops of 10% KOH
After 2 to 10 minutes small globular arthrospores attached
to the shaft are visible
22
23. Dermatophyte Testing
Wood lamp
Ultraviolet light source
Warm up for 5 minutes before use
Results may be ambiguous
Only about 50% of cases
Must be at the right life stage
Hairs infected with some species of Microsporum are a
clear apple-green in a darkened room using fluorescence
23
25. Dermatophyte Testing
Several products available for culturing
Most common – dermatophyte test medium (DTM)
Turns red in the presence of most dermatophytes
25
26. Sample Collection
Clean the lesion to remove surface contamination
Collect samples from lesion periphery
Broken hair shafts and dry scale most likely to contain
viable organisms
Push sample into and partially below the surface of the
media
Incubate at room temperature with loose cap and
observe daily for growth
At first sign of color change, perform a wet prep
using Fungi-Tape or cellophane tape and
lactophenol cotton blue stain
26
27. Test Results
Red color in DTM
Teal in ESM or other media
Alone these are not diagnostic
Must be supported by microscopic examination
27
