Animal Model Quality: Transportation and Environmental Factors

What are the most important factors in assessing the quality of an animal model? In Part I, Quality Considerations In The Use of Animal Models, we discussed two of the four quality considerations for using laboratory mice: health and genetics.

To recap:

  • It's important to understand the different health standards when assessing an animal model. Commercial providers often make them available online, or they can be requested from the sending facility.
  • With genetics, using polymerase chain reaction (PCR) testing to identify the presence or absence of the desired engineered mutation is an important step. Using a Single-Nucleotide Polymorphisms (SNP) test to determine the exact background strain of your mouse model will save time and headaches.

Now to the two remaining quality considerations: environment and transportation.

"Quality is pride of workmanship."

W. Edwards Deming: engineer, statistician, professor, author,
lecturer, and management consultant

Environmental Factors

By environment, we mean the conditions in which your mice are housed. In general, mice are held in standard animal cages with open tops, or in IVC racks with filtered covers. They are fed food ad libitum, drink only water which has been filtered, acidified or chlorinated and live under a strict twelve-hour light cycle. While these are industry standard conditions, in practice they vary from facility to facility, even within the same institution.

If one of these parameters changes, it can have a dramatic effect on study outcomes. As we learn more about the microbiome, we find that environmental conditions can affect the microbiome, causing a downstream effect on your study (Ericsson AC, 2015). If you acquire a model from another lab and find that you are not getting expected results, investigate some of the environmental conditions to see if they vary from the originating animal facility.

Even if you're running your experiment in the same facility and your study gives you unexpected results, check the environmental conditions the mice were housed in previously. These environmental conditions are often taken for granted, but can have a huge effect on the quality of your studies.

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All mice are transported prior to conducting a study. That transit may be down a hallway, across the country or even half way around the world. All transportation, no matter how good it is, has an effect on study outcomes.

During shipment light cycle, temperature and humidity will change many times before the mice arrive at your facility. The goal with transportation is to minimize, to the extent possible, its effects on your study. How is this accomplished?

  • A validated shipping container will keep unwanted organisms out, while allowing fresh air to enter and humidity to exit.
  • Supply adequate food and water not only for the expected length of the shipment, but for an additional day or two in case the shipment gets held up. (Shipping times should be minimized to the extent possible.)
  • The final consideration is acclimation time. Transportation down the hall from the holding room to the procedure room may require only a few minutes of acclimation. An overnight shipment, or longer, can require up to seven days' acclimation.

For a comprehensive review of this subject, we recommend Obernier and Baldwin's Establishing an Appropriate Period of Acclimatization Following Transportation of Laboratory Animals.

Assessing Animal Model Quality

So, are these the only quality considerations?

Absolutely not, but controlling for these four will support consistent results across studies. As a scientist, the goal is to get valid answers to your questions. Using animal models properly is vital to that achievement.

Consideration of the quality parameters discussed here, health, genetics, environment and transportation will go a long way to give you confidence in your results.