CHAPTER 5 PRACTICAL CYTOLOGY 45
This technique appears to have good sensitivity and specificity for the diagnosis of
canine demodicosis (not evaluated in feline patients).
Squeeze tape impressions are typically less invasive and may be more easily performed
on multiple body sites or when dealing with a fractious animal.
OTIC SWABS/SMEARS
Used to diagnose bacterial and yeast overgrowth as well as to support the diagnosis
of other differentials (neoplasia, keratinization disorders, mites, fungal infections); otic
cytology should be performed on otitis cases at every examination (Table 5.1).
Obtain the sample for cytology by positioning a cotton swab at the juncture of the
vertical canal and the horizontal canal (approx. 75◦angle; use caution straightening
the canal to avoid puncturing tympanum).Roll the sample onto a glass slide; if desired, form letters R and L (or use the right
and then left side of the slide) to identify which ear the sample represents so both
samples can be placed on the same slide (Figure 5.7).Heat-fix the slide by passing a flame under the slide for 2–3 seconds (optional).
Use Diff-Quik®stain (modified Wright’s stain) and gently rinse the slide, being careful
not to dislodge the sample.
Initially examine the slide under 10×objective to identify the best field for observa-
tion; then use 40×, 100×, or oil immersion to identify the organisms and/or cellular
population.TABLE 5.1. Arbitrary scale for quantifying bacteria and yeast (external canal)Per high power (400×)fieldScale bacteria0 None1 Fewer than 1–2 organisms2 2–5 organisms3 5–20 organisms4 More than 20Scale yeast0 None1 Fewer than 121 –535 –104 More than 10