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Veterinary Laboratory Investigation and Response Network


Veterinary Laboratory Investigation and Response Network logo - 8/2014


Our Mission

To promote human and animal health by collaborating with veterinary diagnostic laboratories to

  • provide scientific information to internal and external stakeholders
  • build laboratory capacity for routine and emergency response
  • train scientists

To help CVM investigate potential problems with CVM-regulated products, including

  • animal food
  • animal drugs

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We Investigate Animal Illnesses Caused by Food or Drugs

Is your animal sick? Do you think it was the food? Or a drug?

Submit a Complaint


Figure 1. What Happens During a Case Investigation?

CVM Reviews the complaint for 3 possible actions: regulatory action, monitor for similar complaints, or Vet-LIRN gathers more information. During a Vet-LIRN case investigation, we collect animal medical records and conduct owner interviews. We test animal samples such as stool, urine, blood, and tissue at our network labs. We use this information to decide if the illness was caused by the food or drugs. If likely, FDA initiates possible regulatory action. If unlikely, FDA monitors for similar complaints.

We investigate potential animal food issues (Figure 1).
We are an important part of the food safety team at CVM. 

Learn more about some of our cases:

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Resources for Animal Owners and Veterinarians

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Tracking Antimicrobial Resistance in Bacteria from Sick Animals

Why track resistance in bacteria?

Antimicrobial resistance is an important public health issue because if antibiotics and similar medicines become ineffective, many infections will be more difficult to treat. In March of 2015, a presidential initiative was released to combat antibiotic resistant bacteria. This national action plan guides government, public heath, healthcare, and veterinary partners in addressing antimicrobial resistance. As part of this plan, Vet-LIRN was tasked to develop, expand, and maintain antimicrobial susceptibility testing (AST) and whole-genome sequencing (WGS) testing of veterinary pathogens isolated at veterinary diagnostic laboratories. To successfully monitor the antimicrobial susceptibility of bacterial pathogens, it is vital that veterinary diagnostic laboratories be incorporated into the nation’s other surveillance activities. Vet-LIRN is committed to being a partner in such an effort.

What progress have we made?

  • During 2017-2018, the Vet-LIRN Program Office coordinated a two-year pilot project to evaluate the feasibility of using Vet-LIRN veterinary diagnostic laboratories to monitor the antimicrobial susceptibility of three veterinary pathogens: Escherichia coli and Staphylococcus pseudintermedius in dogs and Salmonella enterica in any host. Approximately 5,000 isolates from clinically sick animals were collected and tested (Figure 2). A publication summarizing the 2017 findings is here.
  • Twenty Vet-LIRN Source diagnostic laboratories collected isolates and tested their antimicrobial susceptibility using Clinical and Laboratory Standards Institute (CLSI) methods. Additional information about the pathogen (the organ it came from, the animal species, which part of the country) was reported.
  • In 2018-2019 additional labs began collecting and sequencing isolates. 
  • Each Source lab was partnered with one of four WGS laboratories.
  • WGS laboratories sequenced a subset of the isolates submitted by their Source labs and uploaded all sequences to National Center for Biotechnology Information (NCBI) through the GenomeTrakr program.
  • Currently, there are 30 Source laboratories collecting the isolates (25 labs in U.S., and 5 labs in Canada) and six laboratories sequencing the isolates (Figure 3).
  • As of  January 2021, we collected antimicrobial susceptibility data for  approximately 12,800 tested and approximately 4,000 isolates were sequenced. 
  • The data so far provides a snapshot of the susceptibility of pathogens being cultured at referral veterinary laboratories. 
  • Vet-LIRN is partnering with the National Antimicrobial Resistance Monitoring System (NARMS) to make the data public, with animal pathogen data being reported in conjunction with the National Animal Health Laboratory Network (NAHLN).

Figure 2. Vet-LIRN AMR Surveillance: what are we doing?

The Source labs collect animal isolates of Salmonella, E. coli,  Staphylococcus pseudintermedius, and others. The labs then perform antimicrobial susceptibility testing and generate a standardized lab report of the results. Isolates are sent from the source labs to the Whole Genome Sequencing labs for sequencing. After the isolate is sequenced, the data is submitted to the National Center for Biotechnology Information for public sharing.

Figure 3: Geographic distribution and organization of Vet-LIRN WGS and Source laboratories (2021)

Map of the United States showing 6 sequencing labs (5 in US and 1 in Canada) and thirty source laboratories (25 in US and 5 in Canada). Almost all states are represented as either a source and/or sequencing lab.

Legend: Thirty Source laboratories (25 in the U.S. and 5 in Canada) (squares) are collecting isolates. Six WGS labs (triangles) have 5 collaborating source labs each and sequence a subset of the isolates submitted by their source labs. Remaining Vet-LIRN laboratories, currently not participating in the project, are shown with circles.

Vet-LIRN Laboratory Funding

Vet-LIRN Cooperative Agreements facilitate participation in Vet-LIRN activities such as case investigations, emergency exercises, proficiency tests, and laboratory accreditation. The agreements also increase the agency’s capability to analyze an increased number of samples in the event of animal food- or drug-related illnesses or other large-scale emergency events that require increased testing of implicated diagnostic or animal food samples. The new agreement allows network laboratories to request additional funds if they are participating in a specific Vet-LIRN project, such as the Antimicrobial Resistance (AMR) Project or if they are conducting whole-genome sequencing (WGS) work, or if their caseload is particularly heavy. Additional funds may also be provided to respond to emerging diseases such as COVID-19.

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Ensuring Accurate Results

A scientist is pipetting liquid into a test tube.

We collaborate with the FDA’s Center for Food Safety and Nutrition (CFSAN) Division of Food Processing Science and Technology (Moffett Center) and the Institute for Food Safety and Health, Illinois Institute of Technology to conduct Proficiency Tests (PTs) and Interlaboratory Comparison Exercises (ICEs) to ensure FDA receives accurate test results from our network laboratories. Samples are sent to the laboratories and test results are submitted to the VPO. Data is evaluated, and final reports are provided to the laboratories.

Recent Proficiency Tests

1. Detecting Salmonella  Typhimurium and Listeria monocytogenes in raw dog foods
    Timely because of the recent increase in raw pet food recalls due to bacterial contamination with pathogens such as Listeria and Salmonella

2.  Detecting Campylobacter in dog feces
     Timely due to the recent Campylobacter outbreaks related to contact with pet store puppies.

3. Detecting unknown toxicant in porcine liver

  • Why is this important?  It evaluates network laboratories’ abilities to identify the cause of an animal illness based on a case history and subsequent testing including histopathology and toxicant testing. The unknown toxicant was Monensin. 

4.  Detecting SARS-COV2
     Timely to support veterinary diagnostic laboratories ability to evaluate the accuracy of their current testing systems.

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Veterinary Student Opportunities

Veterinarians are valuable partners in CVM’s mission to promote animal health. Vet-LIRN is committed to building relationships with the next generation of veterinary professionals. Veterinary students can apply for an externship through the FDA Veterinary Clerkship Program to train alongside Vet-LIRN team members. Students will learn more about CVM’s mission and be introduced to the many different roles that veterinarians play within the Center.

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Veterinarians, Want to Learn More?

Vet-LIRN educates veterinarians and students about how to identify and report suspected animal food issues via webinars and case studies. Vet-LIRN speaks at various conferences, to veterinary interest groups, and to students. Please email [email protected] if you would like Vet-LIRN to speak to your organization.

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Preparing for and Responding to Emergencies

Vet-LIRN participates in the planning, play, and evaluation of emergency preparedness and response activities. Such activities strengthen the Program Office’s ability to establish and initiate strategies to coordinate the roles and responsibilities of veterinary diagnostics laboratories in real-world emergency events. Knowing the network laboratory capabilities and having routine interactions and exercises with the laboratories is key to any emergency response. The Vet-LIRN Program Office routinely communicates with the following laboratory networks and programs to harmonize and leverage activities and participate in an integrated response to national emergencies: 


Vet-LIRN Program office (VPO) has a very active role in supporting capacity and emergency response related to COVID-19.

  • VPO, in collaboration with FDA’s Center for Veterinary Medicine’s Office of Surveillance and Compliance, facilitates necropsies of animals excluding production animals that have tested positive for or been exposed to SARS-CoV-2. VPO partnered with USDA’s National Veterinary Services Laboratory, Department of Defense, and CDC to develop a sample checklist to standardize sample collection and archiving for partners conducting necropsies. This work is a part of a One Health approach that has included collaboration with the CDC, state and local veterinarians, and VPO to allow Vet-LIRN network laboratories to conduct necropsies on animals across the nation. To date, three cats, one dog, and one tiger have been necropsied through this collaborative process. This work is important because we are still learning about the disease process in natural exposures in animals. In addition, this collaboration builds on the One Health framework. 
  • In collaboration with numerous partners, Vet-LIRN offers Inter-Laboratory Comparison Exercises (ICE) to evaluate SARS-CoV-2 detection assays at veterinary diagnostic laboratories, private industry, and other government partner laboratories. The first ICE (Round 1) was completed in October of 2020. In collaboration with the USDA’s National Animal Health Laboratory Network (NAHLN), FDA/CFSAN’s Moffett Center Proficiency Test Campus, Cornell University, United States Geological Survey, and the ICLN, VPO conducted a second ICE (Round 2) to evaluate SARS-CoV-2 detection assays in June 2021. 
    • ICE1: Veterinary diagnostic laboratories developed tests for SARS-CoV-2 in animals in spring 2020. These methods were initially evaluated only in the originating laboratories. The Round 1 ICE allowed laboratories to evaluate their individual assays in comparison to assays run by other laboratories. Private commercial laboratories also participated. In August 2020, the Moffett Center shipped samples to over 40 participating laboratories. Sample preparation and analysis of results were completed following ISO Guidelines 13528 and 16140. Results showed that for RNA in buffer, 100% of samples were detected, and for samples requiring extraction, PCR methods provided almost perfect results. 
    • ICE 2: The round 2 ICE was conducted in June 2021 and included SARS-CoV-2 and non-SARS-CoV-2 coronavirus samples at various concentrations to evaluate sensitivity and specificity of participants’ methods and their ability to detect emerging variants. Participant laboratories included those in the Vet-LIRN and NAHLN networks, as well as CDC, DOD, USGS, EPA, and private laboratories. ICE2 is even more relevant now because 25 veterinary diagnostic laboratories are testing human samples for the SARS-CoV-2 virus under Clinical Laboratory Improvement Amendments (CLIA) certifications and have tested millions of human diagnostic samples. 

While Vet-LIRN’s efforts related to COVID-19 are focused on emergency response, they also promote and protect human and animal health. The veterinary diagnostic laboratory community is building laboratory capacity, training scientists, and providing critical scientific information to federal stakeholders. VPO is focused on ensuring results gathered by network laboratories are accurate and meaningful to advance our ability to respond to the pandemic. 

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Deng K., et al., Interlaboratory Comparison Exercise (ICE) of SARS-CoV-2 Molecular Detection Assays Being Used by Veterinary Diagnostic Laboratories. Journal of Veterinary Diagnostic Investigation. Accepted.

Nemser, S., et al., A review of proficiency exercises offered by the Veterinary Laboratory Investigation and Response Network (Vet-LIRN) and Moffett Proficiency Testing Laboratory from 2012 to 2018. Accreditation and Quality Assurance, 2021. 26(3): p. 143-156.

Tyson, G.H., et al., Genomics accurately predicts antimicrobial resistance in Staphylococcus pseudintermedius collected as part of Vet-LIRN resistance monitoring. Veterinary Microbiology, 2021. 254: p. 109006.

Tkachenko, A., et al., Extensive evaluation via blinded testing of an UHPLC-MS/MS method for quantitation of ten ergot alkaloids in rye and wheat grains. J AOAC Int, 2021.

Vudathala, D., et al., A Lateral Flow Method for Aflatoxin B1 in Dry Dog Food: An Inter-Laboratory Trial. J AOAC Int, 2021.

Jones, J.L., et al., Whole genome sequencing confirms source of pathogens associated with bacterial foodborne illness in pets fed raw pet food. J Vet Diagn Invest, 2019: p. 1040638718823046.

Tyson, G.H., et al., Complete Genome Sequence of a Carbapenem-Resistant Escherichia coli Isolate with bla NDM-5 from a Dog in the United States. Microbiol Resour Announc, 2019. 8(34).

Nichols, M., et al., Detecting national human enteric disease outbreaks linked to animal contact in the United States of America. Rev Sci Tech, 2020. 39(2): p. 471-480.

Tonyali, B., et al., An analysis of cellulose- and dextrose-based radicals in sweet potatoes as irradiation markers. J Food Sci, 2020. 85(9): p. 2745-2753.

Taghvaei, M., et al., Solid-phase micro extraction of food irradiation marker 2-dodecylcyclobutanone (2-DCB) from chicken jerky treated with glycerol. J Food Sci, 2020. 85(8): p. 2608-2614.

Cole, S.D., et al., New Delhi Metallo-β-Lactamase-5-Producing Escherichia coli in Companion Animals, United States. Emerg Infect Dis, 2020. 26(2): p. 381-383.

Vudathala, D., et al., Multilaboratory Evaluation of a Lateral Flow Method for Aflatoxin B1 Analysis in Dry Dog Food. J AOAC Int, 2020. 103(2): p. 480-488.

Ceric, O., et al., Enhancing the one health initiative by using whole genome sequencing to monitor antimicrobial resistance of animal pathogens: Vet-LIRN collaborative project with veterinary diagnostic laboratories in United States and Canada. 2019. 15(1): p. 130.

Jones, J.L., et al., Information for veterinarians on reporting suspected animal food issues. J Am Vet Med Assoc, 2018. 253(5): p. 550-553.

Reimschuessel, R., et al., Multilaboratory Survey To Evaluate Salmonella Prevalence in Diarrheic and Nondiarrheic Dogs and Cats in the United States between 2012 and 2014. J Clin Microbiol, 2017. 55(5): p. 1350-1368.

Mitchell, E.P., et al., Pathology and Epidemiology of Oxalate Nephrosis in Cheetahs.Veterinary Pathology, 2017. 54(6): p. 977-985.

Tkachenko, A., et al., Investigation of melamine and cyanuric acid deposition in pig tissues using LC-MS/MS methods. Food and Chemical Toxicology, 2015. 80: p. 310-318.

Nemser, S.M., et al., Investigation of Listeria, Salmonella, and toxigenic Escherichia coli in various pet foods. Foodborne Pathog Dis, 2014. 11(9): p. 706-9.

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