Page 394 - The Veterinary Laboratory and Field Manual 3rd Edition

chapter 8

Pathology/cytology

Susan C. Cork

8.1 Introduction tory for further analysis. Histopathology services
are usually beyond the capability of district
The provision of pathology services should be an laboratories but are discussed briefly in section
integral part of veterinary service development, 8.3. In cases where tissues are already decom-
especially in rural areas where access to a wide posed histopathology may not be justified as any
range of ancillary diagnostic tests is limited. In changes seen could be a result of post-mortem
rural settings, it is of great value to have access change as opposed to disease. Guidelines for the
to veterinary professionals and animal health collection and submission of samples for other
technicians trained to recognize the gross tissue tests, for example, microbiological and parasito-
changes or lesions typical for disease conditions logical examination, are outlined briefly below
common to the area. In hot humid climates but are also discussed in the relevant chapters.
carcasses may putrefy quickly, making samples Supplementary necropsy guidelines are available
unsuitable for microbiology and other tests, and in Appendix 2 and online.
so gross post-mortem or ‘necropsy’ may be the In most countries, there are strict regulations
only ‘test’ available. At fresh post-mortems (that regarding the sending of pathological specimens
is, when the animal has recently died or has been through the post or via courier. It is the responsi-
euthanized) the selection of specific samples will bility of the submitter, or the referring laboratory,
depend on the nature of the disease(s) suspected to obtain a copy of the relevant transport regula-
and on the experience of the operator (techni- tions and to ensure that the correct packaging and
cian, veterinarian or animal health extension labelling are used before sending samples on to a
staff). In general, the post-mortem should diagnostic facility. All specimens must be clearly
be carried out according to a set protocol and addressed and marked with the words ‘FRAGILE,
performed in a methodical manner so that key HANDLE WITH CARE – PATHOLOGICAL
findings are not missed. SPECIMEN’. Specimens should be sent in sealed
More detailed examination of cellular changes containers as in Figure 8.1 and enclosed in protec-
in tissue samples for diagnostic purposes is tive wrapping to prevent breakage and/or leakage
known as histopathology. To ensure good tissue en route to the diagnostic or referral laboratory.
preservation the samples should be fixed in a fix- Guidelines for sending samples to international
ative, such as 10% buffered formalin. This should reference facilities are found in the OIE Manual
be added to the sample container at a volume of for Diagnostic Tests and Vaccines for Terrestrial
10 : 1 and sent to a regional or reference labora- Animals (see also Chapter 1).

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