(i) Select a suitable needle. The length is selected in order to be inserted into all areas of the mass. Typically 0.5 - 2.0cm, 22 gauge for lymph nodes and large tissue masses and 25 gauge for small lesions and skin growths.

(ii) Local anaesthesia is usually not required and should be avoided if the lesion is superficial. First swab the skin with alcohol. Fix the lesion between thumb and forefinger and introduce the needle halfway into the lesion. Attach a 10ml syringe and apply suction by drawing back the plunger. Sample multiple sites in the lesion without withdrawing the needle to avoid aspirating into the barrel of the syringe. The aspirate will often not be seen in the barrel of the syringe but sufficient cells will be aspirated into the needle to prepare slides.

(iii) Release the suction and withdraw the needle. Remove the needle, draw air into the syringe and carefully expel sample onto two clean glass slides. Prepare smears using the same technique as for blood smears and rapidly air dry by waving in the air. Often the aspirate is too viscous for this technique. The method of choice is then to lay a clean glass slide flat on the slide with the aspirate and to draw the two slides apart horizontally (Morris and Dobson, 1992). Alternative techniques for smear preparation were reviewed by Tyler et al, 1989.

(iv) Any remaining sample may be preserved by drawing cytological preservative into the syringe and returning the suspension to the glass vial (available free of charge on request).

(v) Collection of fluid from fluid filled masses and cysts requires a 21 to 25 guage needle and a 3ml syringe. Swab the skin above the lesion with alcohol and aspirate 1 to 3ml of fluid. Prepare fresh smears as above and expel any remaining fluid into an EDTA tube (for cell counts and protein analysis) and into cytological preservative (for further concentration and cytological exmination as required). If an abscess is suspected then submit either a swab in transport medium or fluid in a sterile container for bacterial culture.

(i) Moisten a sterile cotton swab with sterile 0.9% NaCl. This may not be necessary in the case of exudative otitis externa.

(ii) Gently scrape or roll the swab across the lesion. An aural swab is usually obtained by passing the swab through an auroscope to sample the horizontal canal. Conjunctival swabs are obtained by first cleaning the conjunctival sac (sterile saline) and then inserting a swab into the conjunctiva and scraping to harvest cells. Topical anaesthesia is recommended for the collection of conjunctival scrapings.

(iii) Prepare two smears by gently rolling the swab along clean glass slides and rapidly air dry. In the case of aural swabs these smears should be examined microscopically before they dry for the presence of ear mites. Do not rub the swab across the slide as this will cause cell damage.

(i) Remove any scab material and gently touch a clean glass slide onto the surface of the lesion. If Dermatophilus congolensis infection is suspected then also imprint the underside of the scab.

(ii) Clean the lesion with a non-irritating antiseptic, wipe dry with a sterile gauze and repeat the imprint.

(iii) Rapidly air dry the smears and label "pre-cleaning" and "post-cleaning".

(i) Rub the edge of a glass slide across the skin lesion. In the case of a conjunctival scraping, first clean the conjunctival sac with sterile saline then apply topical anaesthesia. Insert a flat, round tipped spatula (5-7mm wide) into the conjunctival sac and scrape 3 times in one direction to harvest cells from both the palpebral and the bulbar conjunctiva.

(ii) Deposit the scraping onto 2 clean glass slides and prepare smears by laying a clean glass slide flat on the slide with the scraping and draw the slides apart horizontally (Morris and Dobson, 1992).