Choosing a Health Standard for Your Model

Taconic 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. These five health standards are defined by the progressive exclusion of foreign organisms.

• The general health standard for most immunocompetent models is Murine Pathogen Free™ (MPF™).
• The Restricted Flora™ health standard excludes the same organisms as MPF™ plus five opportunists, as described below.
• The general standard for most immunocompromised models (nudes, scids, NOG) is Excluded Flora (EF), which also excludes Proteus spp. and segmented filamentous bacteria (SFB). Several immunocompentent models such as Swiss Webster, Black 6 and Sprague Dawley® are produced at this more restrictive standard. Recently, we have added production of the BALB/c, C3H, and 129SVE in the US and Black 6, B6JBom, and BALB/c Bom in Europe at the Excluded Flora standard.
• 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.

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 are particularly interested in Excluded Flora, Defined Flora and Germ Free models, since many publications have linked immune response and susceptibility to certain cancers to the microbiome.

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™ 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™ 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™ 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.

Excluded Flora Swiss Webster 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.