Page 235 - The Veterinary Laboratory and Field Manual 3rd Edition

204 Susan C. Cork and Roy Halliwell

sterile glass or plastic bottles. Requests for which is moistened using sterile water. It is
special tests should be made on the submis- important to ensure that the swab does not dry
sion form, that is, Ziehl–Neelsen stain for faecal out so, where possible, it should be placed in
smears where Mycobacterium avium paratuberculo- transport medium to maintain good conditions
sis sp. are suspected or micro-aerophilic culture for isolation of pathogens. It can be useful to
for Campylobacter spp. Note the colour and con- prepare smears from these samples on micro-
sistency of the sample as well as any unusual scopic slides to submit along with the swab(s).
odour. If there is blood or mucus present in the For example, motile trichomonads and protozoa
sample it should also be examined for the pres- may be readily observed in smears of vaginal
ence of parasites such as schistosomes, amoebae mucous.
or coccidia (see Chapter 3). Necropsy examinations (post-mortem sam-
Swabs are used to sample pus and fluids from ples): Tissue samples can be collected during
abscesses, skin wounds and so on. These are post-mortem examinations along with heart
preferably placed in a transport medium, which blood/tissue impression smears and body
contains nutrients for bacterial survival but not fluids (pericardial fluid, pleural fluid, ascitic
proliferation. If transport media are not available fluid). These samples should be submitted
the swab can be kept moist by placing it in a in sealed containers along with details of the
bottle with a little sterile distilled water. Special gross findings observed (see necropsy report
moisture retaining swabs and kits containing form Appendix 2). Submitted tissue samples
transport media are available commercially but (for example, liver, muscle and so on) should

these can be expensive. be at least 2 cm in size. When tissue samples
3
Milk samples should be collected from each are ready to be cultured the surface is seared
quarter of the udder, after cleaning and disin- with a flame and a clean section exposed using
fecting the teats, into sterile containers. Note a sterile scalpel blade. A portion of this tissue
the colour, smell and consistency of the milk is then ground up and mixed with sterile water
samples. If clinical mastitis is present (that or extracted with a sterile loop and inoculated
is, swollen painful teats or udder, discoloured onto standard culture media. Body fluids can be
milk) samples can be cultured directly and a collected aseptically using a syringe and needle,
smear made for later staining. Where subclinical the volume and appearance of the fluid present
mastitis is suspected simple indicators of inflam- should be recorded. Tissue impression smears
mation are useful and screening tests such as can be made by running a clean microscope slide
the Whiteside test and California Mastitis Test along the freshly cut edge of an organ or tissue,
(CMT) can be carried out. For routine screening for example, liver, spleen, bone marrow cavity
of milk, somatic cell counts are often carried out. and stained for cytology. See Chapter 8 for more
Urine samples can be collected directly into explanation.
sterile labelled bottles. However, free caught
urine samples can be heavily contaminated with
normal flora from the gut and reproductive tracts Laboratory examination of specimens
so it is preferable to collect mid-stream samples to
minimize this. In some cases, it may be necessary When samples arrive at the laboratory, the macro-
for an attending veterinary professional to use a scopic appearance of the submitted specimen(s)
sterile catheter to get a representative sample. should be described along with the colour, smell
Nasal secretions, vaginal discharge and eye and consistency. The presence of mucus, blood,
discharges can be collected using a dry swab pus or parasites should also be noted. If indicated,

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