In-house diagnostic pathology and pathology referrals
Review of existing policy ratified October 2000
Policy
Veterinarians offering in-house diagnostic pathology services should ensure that equipment and
services are subject to regular quality control and quality assurance testing. Staff should be thoroughly
trained in the correct use and routine maintenance of diagnostic equipment. When interpreting the
results, staff should be aware of the limitations and interferences that may affect the test results.
Background
Many veterinary practices use in-house clinical pathology, haematology and cytology equipment to offer
a range of diagnostic and treatment monitoring services to their clients.
When veterinarians are choosing pathology services or instrumentation, they need to be aware of two
concepts: quality control (QC) and quality assurance (QA).
QC is the regular processing of a sample with known values (reference values) to monitor the
repeatability of the result. The equipment manufacturer or agent often provide QC samples; however,
the National Association of Testing Authorities (NATA) recommends independent controls wherever
possible. Results are recorded against an expected range, and abnormal results are used to help detect
problems with instruments, reagents or operators. Patient samples should not be run and reported until
QC results have met expected values.
QA is the regular testing of samples with unknown values to test for accuracy. QA is provided by
independent testing organisations or may be as simple as sample exchange programs between
practices and laboratories. It includes determining consensus values derived by comparing the results of
all participants using similar test methodology and equipment. Aberrant QA results may highlight
problems with equipment, training or reagents that warrant further investigation.
Guidelines
General considerations
 The offering of in-house diagnostic pathology testing to clients where appropriate is
considered ‘good veterinary practice’.
 The judgment of the attending veterinarian about the need for pathology testing and the
particular pathology tests used in an investigation or work-up will vary with each clinical
situation or circumstance. A higher standard of competency in the interpretation of pathology
results is expected from specialist veterinary pathologists when using veterinary pathology
services.
 Failure to practise adequate QC and QA may lead to inaccurate and unconfirmed results.
The use of invalidated test results to make judgments on the disease status and prognosis of
animal patients could place the veterinarian at risk of making incorrect diagnosis and
treatment options and could result in legal action.
 Results may be inaccurate or invalid if the instruments used have not been validated for
samples from the common animal species tested or are tested on incorrect sample types or
inappropriately stored and handled samples.
 Errors can be incorporated into the testing system as a result of many staff members (both
lay and professional) using the equipment; this can lead to variability in testing procedures
and their results. Precise, thorough and uniform training of staff on the correct use of
diagnostic equipment is essential. This must include maintenance, troubleshooting, QC and
correct sample handling. Ongoing competency to perform testing must also be assured.
 Qualified personnel must regularly maintain the equipment used.
Features of particular areas of diagnostic pathology
Biochemistry
All practices using in-house biochemistry equipment should undertake regular QC testing, at intervals
appropriate to the equipment being used. The QC material should be appropriate and have reference
values pertinent to the equipment being used and the species being tested and cover the range of
results likely to be encountered. QC data should be checked against the expected range and the results
acted upon before any diagnostic samples are tested.
Where possible, internal QC tests should be supplemented with an external QA program.
Reagents and QC material should be stored under appropriate conditions. Expired reagents must not be
used for diagnostic purposes.
Haematology
The practice should use haematology QC material that is appropriate for the equipment being used. The
QC material should have reference values pertinent to the equipment used. In-house haematology and
biochemistry equipment should have QC run on a daily basis.
Blood films should be made, stained and examined by a veterinarian on all primary diagnostic cases.
Cytology and other microscopic examinations
The practitioner must be aware of the potential value and accuracy of techniques involving microscopic
examination (fine needle aspirates, impression smears, tape preparations and skin scrapings). This
includes the pitfalls and shortcomings associated with sample preparation and examination. Cytology
staining solutions should be regularly replaced. Duplicate samples for diagnosis may be submitted to a
commercial laboratory as a means of internal QC.
Parasitology
The preparation of suitable samples is critical to the accuracy and interpretation of findings.
Microbiology
The accuracy and interpretation of findings from in-house microbiology work is very important. The
incubation process, storage procedures, inoculation procedures and materials must be appropriate and
valid.
Duplicate samples for identification or sensitivity testing may be submitted to a commercial laboratory as
a means of internal QC.
Serology
Negative and positive controls should be run with all diagnostic samples. Such controls are often an inbuilt component of the test system.
Urinalysis
The diagnostic requirement for a complete or partial urine analysis needs to be considered in each
clinical situation. The value of a particular in-house urine analysis procedure – dipstick, specific gravity
(refractometer) or microscopic examination of centrifuged urine – needs to be weighed against the value
of a complete analysis available at a veterinary pathology laboratory.
Necropsy
A necropsy should be offered to a client if the information gained could aid in the diagnosis or treatment
of a wider disease situation, or in the event of an unexpected or untimely death of an animal. An autopsy
may also be appropriate where the client or veterinarian require peace of mind. The owner should be
given the option of deciding who will perform the necropsy: the attending veterinarian, a colleague or an
independent veterinary pathology laboratory. Necropsy should not be performed without the owner’s
consent.
Clients should be offered a complete autopsy to ensure that maximum diagnostic information can be
gathered. Appropriate diagnostic specimens should be taken from all autopsies and stored for future
reference.
Pathology referrals
Veterinarians are referred to the Australian Veterinary Association’s (AVA’s) policy on veterinary
referrals. There are three possible avenues for referral of veterinary clinical pathology and diagnostic
tests:
 commercial, university and government veterinary pathology laboratories
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medical pathology laboratories, preferably with veterinary accreditation
neighbouring practices with appropriate equipment.
All commercial and government veterinary pathology laboratories that perform referral testing should be
accredited to ISO/IEC 17025: General requirements for the competence of testing and calibration
laboratories. Accreditation provides independent assessment of technical competence to perform a
range of testing activities. Refer to the NATA (nata.com.au) for a complete listing of accredited
veterinary facilities. If the practitioner has a choice of commercial pathology laboratories, an accredited
laboratory should be used in preference to an unaccredited laboratory.
Referring veterinarians need to be aware that medical pathology laboratories may not be adequately set
up for handling veterinary testing samples or have the appropriate expertise to understand the limitations
and interpret the results obtained.
Practitioners who refer clinical pathology to neighbouring practices must be aware of and accept the QA
and QC of the testing performed by that practice.
Practitioners who accept referral of clinical pathology from a neighbouring practice must accept
responsibility for the results generated by their equipment.
Consideration should be given to seeking accreditation for the services provided in-house, as per
accredited referral laboratories.
Pathology samples for referral must be collected, stored and handled correctly to optimise the value of
the test results. Samples must be packaged and transported to the referral laboratory in accordance with
any current legislative or industry requirements.
Other relevant policies or position statements
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6.9 Provision of blood supplies for use in dogs and cats
17.1 Veterinary referrals