Small Animal Dermatology, 3rd edition

CHAPTER 5 PRACTICAL CYTOLOGY 47

 For solid nodules/tumors: carefully insert the needle into the center of the lesion,

with the plunger pulled back to provide negative pressure; then release the nega-

tive pressure and repeat the process several times (sometimes while redirecting the

needle).

 Always release the negative pressure prior to removing the needle from the lesion so

that the sample collected remains in the needle or needle hub.

 Alternative method for solid nodules/tumors: draw 2 cc of air into the 6 cc syringe;

using a stabbing motion, insert the needle into several areas of the nodule/tumor

(Figure 5.10).

 Remove the needle from the syringe, fill the syringe with air, replace the needle onto

the syringe, and expel the sample onto a clean microscope slide.

 Prior to staining, the sample should be gently distributed in a thin layer using a second

slide.

 For smaller lesions (such as pustules): gently wipe alcohol onto the surface of the

lesion, air dry, lance the roof of the lesion with a sterile needle, and “scoop up” the

contents with the needle to place on a glass slide (Figure 5.11).

ACETATE TAPE PREPARATION

Used for identification of mites (Cheyletiellaspp.) and yeast.

 Use “clear” acetate tape.

 ForMalasseziaidentification:
Press the suspect area multiple times with the sticky side of the tape (Figure

5.12a)

Stain the tape with a modified Romanowsky stain (i.e., Diff-Quik®)

Do not put tape into the “fixative” to prevent dissolving of the adhesive and

sample loss (Figure 5.12b)

Press the tape (sticky side down) onto a glass slide.

 ForCheyletiellaidentification:
Apply the tape to multiple sites (collecting as much scale as possible)
Directly press tape (sticky side down) onto a glass slide.

COMMENTS

 With direct impression, forcefully press the sample onto the surface of the slide for

greater adherence.

 If heat fixing, heat fixation should be brief – do not “cook” the slide.

 The staining process should be gentle to avoid dislodging the material from the slide

(immerse the slide in each fixative/stain and hold for the allotted time rather than

repeated dippings).

 Use caution when rinsing the slide (low pressure).

 Change stain pots on a routine basis (weekly or when contaminated).