Page 70 - The Veterinary Laboratory and Field Manual 3rd Edition

Setting up and using a laboratory service 39

the bench, in wintertime the samples should agent will die, so a definitive diagnosis cannot
be kept in an incubator at 37°C). The serum be made. Molecular screening methods may
can then be removed and put into a clean, still be possible and are now quite commonly
labelled tube. If you have a centrifuge you can used instead of culture. However, in cases
get more serum by spinning the tube and then where the cause of the disease is unknown
decanting the serum into another vial. If you or where we are dealing with a new disease,
do not remove the serum in a timely manner isolation of the pathogen is still preferable.
the red cells in the clot will slowly break down, Transport the specimens, if possible,
releasing their haemoglobin into the serum, within 48 h. Bacteriology samples should ide-
causing the serum to take on a pink-red colour ally be transported to the laboratory within
which may interfere with subsequent testing. 12 h after sampling.
Once the serum is removed into a separate 2 Keep the samples cool on the way to the labo-
tube, keep it cool until you can get it to the ratory
laboratory. If it will be more than one week Use cold packs to help ensure that the pack-
before the sample can be shipped to the labo- age does not get warm en route but avoid
ratory, freeze it, because antibody levels will direct contact between delicate samples and
slowly fall, even at 4°C. Paired serum samples the cooling units
(collected at the time of, or just before clini- 3 Use packaging that will prevent leakage and
cal disease and again 2–3 weeks later) can crushing
be used to confirm a diagnosis if it is dem- Leakage of contents is a biosafety and bios-
onstrated that the antibody levels have risen ecurity hazard and will cause a package to
over a period of time. For external parasites, be refused by the shipper. Also, the package
mites, fleas, and ticks can all be collected with should be sturdy because if it is crushed, it
forceps and kept in 70% alcohol indefinitely is more likely that samples will be ruined
for later identification. or that leakage will occur. If courier services
4 For faecal samples, fresh faecal samples are used for transporting samples there are
should be kept cool until they can be sent specific guidelines for packaging potentially
to the laboratory. Nematode eggs usually infectious material. Check with your local
survive well at 4°C but can be destroyed by shipper/courier to find out what the required
freezing, so do not freeze samples. The addi- packaging specifications are.
tion of 10% buffered formalin to the faecal 4 Be sure that all your samples are well-labelled
sample aids preservation for parasitology The laboratory needs to know what kind of
examination. For bacteriology examination samples are being submitted and where they
of faecal samples preservative should not be are from. All samples must be labelled with
added to the sample. the animal’s identification number, a note of
what sample it is, from where it is collected
SEndInG SaMPLES to tHE Laboratory and the date of collection.
Some key principles to consider when sending 5 Be sure that appropriate paperwork is
samples to the laboratory include the following. included with the samples
Determining the cause of disease is a team
1 Speed in getting the samples to the laboratory effort. By giving the laboratory staff a com-
The longer the package is in transit, the plete history of the case(s) and noting any
greater the probability that bacterial con- gross necropsy findings, the laboratory is
taminants will proliferate or the pathogenic much more likely to be successful in helping

Vet Lab.indb 39 26/03/2019 10:25