Choosing a Health Standard for Your Model

Taconic Biosciences produces rodent models at several different health standards. How do you know which health designation to choose when ordering animals?

Defining Rodent Health Standards

Taconic rodent models are available at multiple health standards, enabling researchers to choose the most appropriate model for their studies. The standards can be grouped into barrier standards (with exclusion lists) and gnotobiotic isolator standards (in which all organisms in a location are known). A core list of rodent pathogens is excluded from all Taconic Biosciences' health standards.

The following barrier health standards apply to the majority of animals producted by Taconic:

  • The general health standard for most immunocompetent models is Murine Pathogen Free™ (MPF™). This standard excludes known rodent pathogens.
  • The Restricted Flora™ health standard is free of rodent pathogens plus six opportunistic pathogens. Note that Taconic is phasing out most RF™ production in the US and EU in favor of OF™ and EF.
  • Opportunist Free™ (OF™) is free of rodent pathogens and seven select opportunistic pathogens.
  • Excluded Flora (EF) is free of rodent pathogens and 7 select opportunistic pathogens as well as Segmented Filamentous Bacteria, a normal rodent commensal organism shown to impact immune system development.
  • The remaining two health designations are exclusively produced in gnotobiotic isolators. For Defined Flora models, all organisms present in the production isolator are known. Germ Free (GF) or axenic mice are free of all microorganisms. These specially-maintained animals are ideal for microbiome and association studies as they provide a blank slate upon which to associate your flora of choice.
Taconic produces nearly all immunodeficient animals at RF™, OF™ or EF and provides certain standard strains such as Swiss Webster, Black 6 and Sprague Dawley® at these more restrictive standards. These three standards are defined by more biosecure husbandry methods as well as enhanced health monitoring. Selection among RF™, OF™ and EF should be based on which opportunistic pathogens and commensal organisms you wish to control in your experiment.

Opportunistic pathogen or commensal organismRF™ Accepted?OF™ Accepted?EF Accepted?
Beta hemolytic Streptococcus (non Group D)NoNoNo
Klebsiella oxytocaNoNoNo
Klebsiella pneumoniaeNoNoNo
Pseudomonas aeruginosaNoNoNo
Staphylococcus aureusNoNoNo
Pasteurella multocidaNoNoNo
Proteus spp.YesNoNo
Segmented Filamentous Bacteria (SFB, a normal rodent commensal)YesYesNo

Choosing a Health Standard

First, consider the restrictions of your animal facility. Each facility will have a standard for which organisms they do and do not tolerate. Only then can you consider your research application and how animal model health standards may affect your study outcome.

Health Standards for Immunology and Oncology

Researchers in immunology and oncology may be interested in animals across the spectrum of health standards. Typical tumor experiments using immunodeficient mice require animals at more restrictive health standards, but there are increasing links between cancer and the microbiome which may lead investigators to study the impact of microbiome variation. For immunology studies, the range of health standards permits investigators to choose the best experimental model, down to looking at the impact of commensals such as Segmented Filamentous Bacteria (SFB).

Publications on the role of the microbiome in disease progression and development are available in the list of references for the Black 6 rodent model.
We have data to support that certain immunoassays do not perform as well mice at more restrictive health designations such as Restricted Flora™ as they do in Murine Pathogen Free™, whereas for other assays Restricted Flora™, Opportunist Free™, or Excluded Flora is preferred.

Generally, for studies of Experimental Autoimmune Encephalomyelitis (EAE) and Collagen Induced Arthritis (CIA), Murine Pathogen Free™ models tend to produce the desired immune response. Murine Pathogen Free™ models have a response rate of ~100% in these protocols, whereas Restricted Flora™, Opportunist Free™, and Excluded Flora show greater variation and response rates from 30-70%.

In addition, for EAE and CIA studies, disease severity tends to be lower for Restricted Flora™, Opportunist Free™, and Excluded Flora mice, which may make them more suitable for studying early and less severe disease states.

Health Standards for Vaccine Research

Researchers studying new vaccines may want to pilot mice at several health standards, in order to determine the role of gut flora in the immune response. This is where it is useful to have models such as Swiss Webster, which is available at multiple health designations.

Sentinel Use

Excluded Flora Swiss Webster or C3H mice and Sprague Dawley® rats are recommended as sentinels for health testing programs. Since these models are fully immunocompetent, they will demonstrate a more robust immune response than a heterozygous nude model.

Find Your Model

Use our model search to find the models available at the health status you need. If you need additional information to choose a model for your research protocol, contact a Taconic scientist for support.


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