WildLife Group
of the SAVA
Challenges of Wildlife Diagnostic
Pathology
Despite the quantum leaps we have made in
diagnostic techniques and procedures they are of
little benefit if the basics of post mortem procedure,
sample collection and sample preservation are
not adhered to. Many of the diagnostic pathology
investigations we perform are severely hamstrung
by cursory post mortal investigation, poor sample
collection and / or selection and inadequate /
ineffective preservation.
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3. Sample Preservation
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1. Post Mortem Procedure
Design a routine procedure and follow that procedure
the same way with each and every autopsy you
perform. Through repetition it becomes second
nature to look at all the organ systems of the carcass
being examined. Avoid erroneously stopping the post
mortem on finding an obvious but not necessarily
important fatal lesion.
Make full use of the opportunity to collect digital
images (camera or smartphone) of the post mortems
you perform and the lesions you identify. Submitting
these images together with your specimens to
the diagnostic pathologist is extremely useful to
the pathologist evaluating the sections, adds huge
relevance to your pathology report and logarithmically
increases your chances of a definitive diagnosis.
Correlating the pathology report you receive with
the gross images you captured, is an incredibly
useful training technique for lesion recognition and
identification.
As your gross pathology skills develop and expand
your sample selection and collection techniques start
to become more relevant.
2. Sample collection
A pathologist’s definition of a diagnostic biopsy
includes the following
• An adequate amount of tissue is submitted.
• Tissue is well fixed in formalin.
• Tissue/s submitted is/are representative of the
pathological process.
• Tissue is sufficiently free of artifacts to enable a
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definitive evaluation.
Submission form is completed in full including
full history, clinical data and description of the
lesions.
Clinician has included his differentials, rule outs
and thoughts on the submission form.
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Wherever possible only use 10% buffered
formalin as un-buffered formalin results in
excessive hematin pigment deposition in sections
and this can severely compromise histological
examination as well as the interpretation of
Immunohistochemical stains.
Tissue slices collected for histopathology should
not be thicker than 1 cm to ensure adequate
penetration of formalin.
Do not overfill formalin jars with tissue, as this
will result in poor fixation, which permanently
compromises any histopathological examination.
Adhering to the ratio of 1 part tissue to 9 parts
formalin enables good fixation of the tissue
which ensures high quality tissue sections for
histological examination.
Fixation is singularly the most important step for
producing quality histopathology slides.
Conclusion
Diagnostic pathological investigation through
complete post mortem investigation and thorough
histological examination has stood the test of time, as
being the cornerstone of effective disease diagnosis
and monitoring. This situation has not changed and
will not change and so it would be prudent never
to ignore your hard learnt capabilities of clinical
observation and lesion recognition. In the words of
Rafiki from the Lion King “LOOK HARDER” you will be
amazed by what you start to see.
Further Reading
Last, R D; Hill J M, Vorster J H, Bosch S J & Griffiths C. 2010. Vetdiagnostix Laboratory Manual 2nd edn. Serrati Publishers, Pretoria.
O’Toole D. 2010. Monitoring and investigating natural disease by veterinary
pathologists in diagnostic laboratories. Veterin