Why use PCR to detect diseases of horses?
Molecular diagnostic testing using PCR
(Polymerase Chain Reaction) has revolutionized the way
veterinarians, researchers, zoos, animal care facilities and
stables maintain animal health and obtain disease data.
The sensitivity, specificity and speed with which
pathogens and mutations are identified by PCR enable diagnostic, research
and monitoring possibilities unavailable using other
techniques. Molecular techniques represent a dramatically
effective tool for the diagnosis of disease in valuable
populations of horses and other animals.
testing, nucleic acid -- DNA or RNA -- is isolated from a
specimen, then amplified (after an extra reverse transcription
step in the case of RNA) using highly specific primers
complementary to known target sequences. Positive and
controls are run simultaneously; internal controls monitor
extraction and PCR efficiency. Each sample is run in duplicate
aliquots to check repeatability. Amplification is visualized and recorded using state-of-the-art protocols and
samples be collected?
shed intermittently. Therefore, for antemortem testing it is
usually best to collect samples
when an animal is symptomatic. Often pathogen titers spike early
in a bout of symptoms, so ideally samples should be collected
early in a bout of symptoms, and when symptoms are worst. It is
possible for treatments to reduce symptoms and shedding
temporarily but not entirely clear the infection. If treatment
was administered, typically you should wait at least a week
following treatment, and/or until symptoms return, before
collecting a sample for testing.
How is molecular, PCR-based
testing complementary to other kinds of testing?
Cross-reactivity reduces the specificity of many
serological tests: a positive result can be caused by
organisms other than the target. Molecular assays, on the
other hand, are highly specific because they detect genetic
sequence unique to the target pathogen. Even closely related
pathogen strains can often be distinguished.
The influence of some sources of false positives is
reduced in molecular testing, because while other testing
methods detect antibodies to pathogens which may not still
be present, molecular assays detect the genetic material of
the pathogen itself -- a direct indication of presence of
the pathogen in the sample.
Infections can often be identified
very early in a bout of symptoms. Detection is not
dependent on elevated antibody levels, which may take days
or weeks to occur.
Animals with high titres of some viruses can actually
exhibit very low antibody levels as their immune systems are
challenged by an infection. This can result in false
negative diagnoses if antibody testing alone is used.
PCR's exquisite sensitivity allows detection of a target
pathogen in a sample even if present in very low titres, and
even from very small sample volumes.
Many different sample types are appropriate for PCR
testing - not just serum. Check our
assay datasheets for any test's sample requirements.
Since 2004, Zoologix has served animal care professionals with molecular diagnostic testing for
infectious diseases that affect horses and other domestic and
wildlife species. Other testing facilities perform PCR testing
as a sideline. Because we specialize in PCR assays for
infectious diseases of animals, our lab staff are adept at
performing protocols designed to maintain specimen integrity and
maximize assay specificity and sensitivity. We provide fast
turnaround and competitive pricing in each of our assay
independent, dedicated diagnostic laboratory not affiliated with
any clinic or corporate conglomerate, Zoologix is free of
incentives to bias results. Zoologix is owned and managed by
board-certified scientists and seasoned laboratory managers with
extensive experience in molecular biology, biochemistry,
zoology, assay design, quality assurance and lab operations. Our
objective is to provide to the veterinary and research
communities the fastest, highest quality molecular infectious
disease testing available.
Client samples are stored at our lab for six months to
facilitate any followup testing.
Zoologix is headquartered in Chatsworth, in southern California.
We are located near two major airports (LA International and
Burbank), UCLA, USC, CalTech and other regional research