What is PCR?
Polymerase chain reaction (PCR) is a simple yet elegant process that enables the production of virtually unlimited copies of genetic material in the laboratory.
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How is real-time PCR different than conventional PCR?
Real-time PCR is a safer, faster and more robust variation of PCR. Conventional PCR harbors more risk for cross-contamination, is more time consuming and does not allow a quantitative assessment of the quality of the DNA extracted from the sample material.
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Does your test differentiate between vaccinations and infection?
For most of the inactivated vaccines, real-time PCR does differentiate between vaccination and infection. Real-time PCR does not detect the presence of antibodies; therefore, a positive result indicates presence of the pathogen. For this reason, PCR has a higher association with disease than with antibody detection. Detection of viral DNA/RNA may occur within a few weeks after vaccination with a modified live vaccine (MLV) while the vaccine virus is replicating. We recommend a three-week interval after the last vaccination to prevent detection of any DNA originating from the vaccine.
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What does a positive and a negative result mean?
A positive result confirms the presence of the pathogen. A negative result means the pathogen is either not present, below the limit of detection, not detectable by the current PCR assay or that the sample quality was low.
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What is the limit of detection?
Detection limit of a method is defined in various ways. The most accepted definition is the target nucleic acid concentration or number of molecules that can still be amplified in 95% of the experiments.
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What is the diagnostic sensitivity and specificity?
The diagnostic sensitivity describes the probability of a true positive result when the PCR is tested in a positive population. In other words, higher sensitivity means higher probability that you’ll correctly identify all positive samples and won’t miss a diagnosis. The diagnostic specificity is described as the probability of a true negative result when the PCR is tested in a negative population. Higher specificity is the probability that the test is really detecting what you’re testing for and not something unrelated. Therefore, higher specificity increases the probability that a positive result is due to the agent.
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If a test comes back negative, but infection is still suspected, how long should I wait to retest?
This depends on the presence or absence of clinical signs, the pathogen(s) suspected and assay being used. In general, a two- to four-week waiting period is recommended.
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Should I run another confirmatory test alongside the PCR test?
Yes. PCR is a complementary diagnostic procedure and should be run parallel with other diagnostic assays. Depending on the pathogen, this could include complete blood analysis, serology, antigen detection systems (such as SNAP® tests), etc.
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How long can samples be stored in the refrigerator?
Samples can be stored in a refrigerator (4°C) for up to three days (over the weekend).
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How should samples be stored?
Fluids (peritoneal/pleural fluid, whole blood, feces) and swabs can be stored for three days (over the weekend) in a refrigerator (4°C).
Fresh tissues should be sent on ice within 24 hours. Tissues can be stored in a standard freezer at -20°C for up to one week. Paraffin-embedded tissues are acceptable.
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How should samples be sent?
If you use a courier pickup, samples can be submitted with your other laboratory samples. If you use FedEx or DHL, all samples should be shipped according to applicable government and IATA regulations. Send samples in an insulated package with ice packs. Samples should be placed in a secondary container within the package, in case of damage during shipping. Absorbent material should be included in the secondary container in case of leaks or breaks in the primary container.
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What sample type should I submit?
The sample type is specific for each pathogen. Please refer to the sample type overview in the test menu.
Feline Hemotropic Mycoplasma (FHM)
Sample type: Whole blood (2 mL lavender-top tube, EDTA); keep refrigerated.
Canine Distemper Virus (CDV)
Sample types:
- For neurological manifestations: CSF (at least 0.5 mL) and whole blood
(2 mL lavender-top tube, EDTA), keep refrigerated;
- For respiratory manifestations: Deep pharyngeal swab (with visible organic material on swab; please rub firmly) and a conjunctival swab (wipe eye clean, swab inside of eyelid). Please submit dry, plastic-stemmed swabs, without transport media, in the same serum tube or an empty, sterile tube, keep refrigerated;
- For GI manifestations: Whole blood (2 mL lavender-top tube, EDTA) and fecal sample (fecal cup), keep refrigerated;
- With no distinct clinical manifestations: Whole blood (2 mL lavender-top tube, EDTA) and a conjunctival swab (wipe eye clean, swab inside of eyelid). Please submit dry, plastic-stemmed swabs, without transport media, in the same serum tube or an empty, sterile tube; keep refrigerated.
Feline Upper Respiratory Disease Panel (Feline URD Panel)
Sample type: Deep pharyngeal swab (with visible organic material on swab; please rub firmly) and a conjunctival swab (wipe eye clean, swab inside of eyelid). Please submit dry, plastic-stemmed swabs, without transport media, in the same serum tube or an empty, sterile tube; keep refrigerated.
Canine Respiratory Disease Panel (CRD Panel)
Sample type: Deep pharyngeal swab (with visible organic material on swab; please rub firmly) and a conjunctival swab (wipe eye clean, swab inside of eyelid). Please submit dry, plastic-stemmed swabs, without transport media, in the same serum tube or an empty, sterile tube; keep refrigerated.
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How long are samples stored after they are processed?
Samples will be kept up to three days after receipt for re-analysis. The extracted DNA is stored for one year and can be used for re-analysis or further testing.
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If I want to run multiple tests (i.e., PCR and another test–IFA, IgG, ELISA, CBC,
Chem profile, etc.), can I send in one sample for all tests?
Ideally, separate samples should be submitted for PCR.
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How do I confirm whether or not my sample has been received?
Check on the status of your sample online at www.vetconnect.com or call IDEXX at
1-888-433-9987. PCR testing is run daily at our Sacramento facility and you can expect results in 1-3 days.
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Who do I contact with any questions or concerns?
For more information about IDEXX RealPCR™ panels and stand-alone tests, call our Internal Medicine Team at IDEXX Reference Laboratories at 1-888-433-9987, option 4, option 2. IDEXX’s board-certified internal medicine specialists are available to help answer your questions, such as:
- When to use a PCR assay
- How to interpret results
- Treatment recommendations
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What tests do you offer?
Feline Hemotropic Mycoplasma (FHM) Test
Mycoplasma haemofelis (formerly called Haemobartonella)
Candidatus Mycoplasma haemominutum
Candidatus Mycoplasma turicensis
Feline Upper Respiratory Disease (Feline URD) Panel
Chlamydophila felis
Feline calicivirus (FCV)
Feline herpesvirus-1 (FHV-1)
Bordetella bronchiseptica
Mycoplasma felis
Canine Distemper Virus (CDV) Test
Canine Respiratory Disease (CRD) Panel
Bordetella bronchiseptica
Canine adenovirus type 2
Canine distemper virus
Canine herpesvirus-1
Canine parainfluenza virus type 3
Canine influenza virus
Canine respiratory coronavirus
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Can additional testing be requested after a sample has already been processed?
The original samples are stored for three days. However, the extracted DNA from the sample is stored for one year. Additional tests can be requested on stored DNA when appropriate. For example, if originally only a distemper PCR was ordered, a full canine respiratory panel can be performed on the stored DNA if the original sample was a conjunctival swab and pharyngeal swab and not whole blood.
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What is the turnaround time for samples submitted to your facility?
PCR test for all pathogens are run daily Monday through Friday. Turnaround time for a sample is 24 hours after receipt of the sample at the West Sacramento facility. Samples delivered on Saturday or Sunday are processed on Monday. Including shipping time, you can expect results in 1–3 working days.
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Are other real-time PCR tests going to be available soon?
We have an extensive list of tests in research and development. Fourteen tests are available as of June 2007. Other assays will become available later this year.
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