Research Associates Laboratory (RAL) – Diagnostic Testing for Emerald Tree Boas

PCR testing is the most powerful tool available to ETB keepers for detecting pathogens before clinical signs appear, confirming a suspected diagnosis, monitoring a collection after a positive case, and making informed decisions about quarantine release. This page explains what PCR testing is, how to use it, and how to interpret what the results actually tell you. It also profiles Research Associates Laboratory (RAL), the molecular diagnostic laboratory most commonly used by ETB keepers and the lab referenced throughout the disease pages on this site.

🌐 Website: vetdna.com📞 Phone: (972) 960‑2221

Testing is most valuable when coordinated with a reptile-experienced veterinarian who can help interpret results in the context of the individual animal's clinical picture. A positive or negative result alone does not tell the whole story.

What PCR Testing Is

PCR stands for Polymerase Chain Reaction. It is a molecular technique that detects the presence of specific genetic material, typically DNA or RNA, from a target pathogen in a submitted sample. The test works by amplifying tiny quantities of pathogen nucleic acid if they are present in the sample, making even very low levels detectable. This is what makes PCR substantially more sensitive than older diagnostic methods such as culture, direct microscopy, or antibody testing for many pathogens.

Standard PCR returns a binary result: positive or negative. The pathogen's genetic material was either detected in the sample or it was not. This is useful but has limitations, particularly when pathogen load is very low or shedding is intermittent.

Real-time PCR, the method used by RAL, goes further by also quantifying how much pathogen DNA or RNA is present in the sample. Results are reported as Positive, Low Level Positive, or Negative. A Positive indicates the organism is present at a detectable level. A Low Level Positive means that genetic material from the organism was detected but in very small quantity. A Negative indicates the organism was not detected in the tested sample. The ability to quantify load is clinically meaningful: it gives a veterinarian a starting point for assessing where an animal is in the disease process, can help distinguish active shedding from residual environmental contamination, and allows monitoring of whether pathogen levels are declining during treatment or quarantine. A standard PCR result of negative in a low-shedding animal may reflect a true absence of infection or may simply reflect a moment when the animal was not actively shedding. Real-time PCR with quantification adds resolution that binary results cannot provide.

Sample Types and What They Are Used For

The sample type submitted has a significant effect on test sensitivity for different pathogens. Not all pathogens are shed equally across all body sites, and selecting the right sample type for the pathogen you are screening for matters.

Oral and choanal swabs are the primary sample type for respiratory pathogens including Nidovirus, Ophidian Paramyxovirus (ferlavirus), and Chlamydia. These pathogens have tropism for the oral cavity and upper respiratory epithelium and are shed in oral secretions. Oral swabs are the recommended front-line sample for quarantine screening of any new boid acquisition. For nidovirus specifically, an oroesophageal swab reaching further down the alimentary tract may improve sensitivity.

Cloacal swabs complement oral swabs for pathogens that are also shed via the cloaca. Arenavirus (Inclusion Body Disease), nidovirus, and ferlavirus have all been detected in cloacal samples. Submitting both oral and cloacal swabs in the same collection increases the probability of detecting intermittent shedders compared to either swab alone.

Fecal samples are the primary sample type for gastrointestinal pathogens including Cryptosporidium serpentis, Helicobacter, and intestinal parasites such as Entamoeba invadens. Because Cryptosporidium sheds oocysts intermittently, a single negative fecal PCR does not rule out infection, and serial fecal submissions across multiple timepoints are more informative than a single test.

Whole blood is used for Arenavirus (IBD) detection and for blood parasites. Blood smear examination for inclusion bodies is a complementary but separate technique performed at a veterinary clinic rather than at a molecular lab.

Gastric lavage samples (stomach washings collected under sedation) are used when Cryptosporidium is suspected but fecal PCR results have been negative or equivocal. This is a more invasive procedure requiring veterinary administration but offers higher sensitivity for C. serpentis than fecal sampling because it directly samples the stomach where the parasite resides. Gastric lavage is typically reserved for cases with strong clinical suspicion and negative or inconclusive initial fecal results.

Environmental swabs from the enclosure, water bowls, and cage furniture can detect pathogen DNA persisting in the environment after an animal has been removed or treated. RAL offers environmental DNA screening that uses the same real-time PCR technology as clinical testing. This can be valuable for confirming whether enclosure decontamination has been successful after a confirmed positive case or for screening a new enclosure's environment before introducing an animal.

Understanding Your Results

This section covers the most important interpretive points for ETB keepers receiving PCR results for the first time.

A positive result confirms the presence of pathogen DNA or RNA in the sample submitted. It does not by itself tell you how sick the animal is, whether it will develop clinical disease, or what the prognosis is. Those questions require clinical assessment by a veterinarian alongside the test result. A positive for nidovirus in a clinically healthy boid, for example, may represent an early or subclinical infection that warrants monitoring and isolation rather than an immediately dire prognosis. Context matters.

A low level positive means that very small quantities of pathogen genetic material were detected. This can occur early in an infection before the pathogen has established strongly, during recovery when the pathogen is being cleared, or during a period of intermittent low-level shedding. A low level positive is not a clean negative and the animal should be managed as potentially infected pending repeat testing and veterinary review.

A negative result means the pathogen was not detected in the sample submitted at the time of collection. It does not guarantee the animal is free of that pathogen. The most important limitation is intermittent shedding: many pathogens covered on this site, including Cryptosporidium, Chlamydia, Arenavirus, and nidovirus, are not shed continuously. An animal can be infected and actively harboring a pathogen while not shedding detectable quantities at the moment the sample is collected. This is why single-test-negative results during quarantine should not be treated as a definitive clearance, and why repeat testing at intervals throughout a full quarantine period is recommended practice.

The prolonged incubation periods of some pathogens mean that testing too early may miss recent infections entirely. Arenavirus in particular may not produce detectable systemic levels for months after exposure. A snake tested negative on intake and re-tested positive six months later does not necessarily mean it was re-exposed. It may simply have been below the detection threshold at first testing. This is covered in more detail on the IBD and Nidovirus pages.

Repeat testing over time is more reliable than any single result. For high-stakes decisions such as releasing an animal from quarantine, retiring a positive result as truly resolved, or making euthanasia decisions based on a confirmed diagnosis, multiple tests across different timepoints and ideally different sample types give a far more complete picture than a single submission.

When to Test

Quarantine intake testing should be performed on every new acquisition regardless of source, captive-bred status, or the seller's assurances. Oral and cloacal swabs for respiratory pathogens and fecal submission for gastrointestinal pathogens should be the baseline. Blood for Arenavirus (IBD) is recommended for any animal entering a boid collection. See the Quarantine page for the full quarantine framework.

Repeat testing during quarantine at the midpoint and end of the quarantine period catches intermittent shedders that tested negative on intake. For a 90-day quarantine, testing at intake, at 45 days, and at 90 days provides substantially more confidence than a single intake test. Animals with longer quarantine periods should be tested at proportional intervals.

Symptomatic animals should be tested as part of any veterinary workup for unexplained respiratory signs, chronic regurgitation, weight loss, neurological signs, or any presentation consistent with the diseases covered in the disease section of this site. A broad panel submission is more cost-effective than piecemeal individual pathogen testing when the presentation is non-specific. See the Chronic Regurgitation page for the workup framework specifically relevant to that presentation.

Collection-wide screening after a confirmed positive case should cover every animal that shared airspace, equipment, or direct contact with the affected individual. Depending on the pathogen identified, the entire collection may warrant testing regardless of apparent health. This is especially important for Arenavirus, nidovirus, and ferlavirus, which can spread silently through a collection before any animal becomes visibly symptomatic.

Pre-breeding testing is recommended before pairing animals. Vertical transmission has been documented or suspected for several pathogens on this site including Arenavirus and Chlamydia. Confirming both animals are negative before breeding reduces the risk of transmitting infection to offspring.

Research Associates Laboratory (RAL)

Research Associates Laboratory is the veterinary molecular diagnostic laboratory most commonly used within the ETB keeping community and the lab referenced throughout the disease pages on this site. Founded in 1992, RAL is the oldest veterinary molecular diagnostic laboratory in the United States and offers next-day results five days per week, including same-day turnaround for overnight submissions. All testing uses real-time PCR with quantitative results.

Website: vetdna.com Phone: (972) 960-2221 Address: 411 East McDermott Drive, Suite B, Allen, Texas 75002

Pet owners and breeders can submit samples directly without a veterinarian by ordering RAL's sample collection kits. A Reptile/Amphibian Submittal Form is available on their website. Coordinating with a veterinarian is still recommended for result interpretation, particularly for any positive or low level positive results requiring a clinical management decision.

RAL Reptile and Amphibian Test Menu

The following pathogens are currently available for individual testing through RAL's reptile and amphibian panel. Pathogens covered in detail on this site are linked to their dedicated disease pages. This list represents individual test options; panels combining multiple pathogens can be requested and are more cost-effective for quarantine screening than ordering tests individually.

  • Aeromonas hydrophila (Red Leg Disease)

  • Arenavirus (Inclusion Body Disease) — see IBD page

  • Aspergillus

  • Atadenovirus (Agamid)

  • Babesia

  • Bartonella

  • Campylobacter

  • Candida

  • Chlamydia — see Chlamydia page

  • Chytrid Fungus (Batrachochytrium dendrobatidis)

  • Chytrid Fungus (Batrachochytrium salamandrivorans)

  • Clostridium

  • Cryptosporidium Genus

  • Cryptosporidium serpentis (Snake) — see Cryptosporidium page

  • Cryptosporidium saurophilum (Lizard)

  • E. coli

  • Entamoeba invadens

  • Giardia

  • Helicobacter (Reptilian) — see Helicobacter page

  • Iridovirus

  • Klebsiella pneumoniae

  • Leptospirosis

  • Leishmania

  • Listeria monocytogenes

  • MRSA

  • Mycobacterium chelonae

  • Mycobacterium marinum

  • Mycobacterium ulcerans

  • Nidovirus (Python/Serpentovirus) — see Nidovirus page

  • Ophidiomyces ophiodiicola (Snake Fungal Disease)

  • Ophidian Paramyxovirus (Ferlavirus) — see Ophidian Paramyxovirus page

  • Ophionyssus Mite — see Snake Mites page

  • Pasteurella multocida

  • Plasmodium (Malaria)

  • Ranavirus

  • Reptile Borna Virus

  • Ringworm (Dermatophytes)

  • Salmonella

  • Sarcocystis

  • Sunshine Virus

  • Toxoplasma gondii

  • Trypanosoma

  • West Nile Virus

  • Yellow Fungus (Chrysosporium anamorph of Nannizziopsis vriesii)

RAL also offers environmental DNA screening using the same real-time PCR platform, which can be used to test enclosure surfaces, water bowls, and substrate for pathogen DNA after a positive case or as part of a decontamination verification process. Sample collection kits and submittal forms are available directly from RAL's website.

Recommended Quarantine Testing Protocol for ETBs

The following is a practical baseline testing framework for a newly acquired Corallus caninus or Corallus batesii. Individual circumstances may warrant additional testing depending on the animal's origin, clinical presentation, and the pathogens present in the source collection.

At intake (day 1 to 7): oral and choanal swabs for Nidovirus, Ophidian Paramyxovirus, and Chlamydia; cloacal swab for Arenavirus (IBD); fecal submission for Cryptosporidium serpentis and Helicobacter. If the animal has come from a collection with known boid contact or unknown health history, add whole blood for Arenavirus.

At midpoint (day 45): repeat oral, cloacal, and fecal submissions. This catches intermittent shedders that were in a non-shedding phase at intake and animals whose pathogen load was below detection threshold at first testing.

At close of quarantine (day 90): repeat full panel. Two clean tests across the full quarantine period provide substantially more confidence than a single intake result. For animals with a positive or low level positive at any earlier timepoint, consultation with a veterinarian about extended quarantine and repeat testing schedule is required before integration with an established collection.

See the Quarantine page for the full quarantine protocol including housing, hygiene, and handling practices during the quarantine period. See the Diseases Overview page for the full list of pathogens documented in this genus.