Reproducibility vs. Vibration and Noise Impacts in Animal Labs

Nature’s Lab Animal journal has published an interesting collection of articles regarding experimental reproducibility in animal models. Unsurprisingly, stressors like noise and vibration figure into the discussion. As we’ve noted before, this is precisely our goal for design and monitoring in laboratory facilities: minimize confounding variables; reduce the number of animals and time required to obtain good data; and improve animal welfare.

There are a lot of interesting papers in this issue, but here are some links to those with some relevance to noise and vibration impacts, along with a bit of commentary on how I think these items relate to lab facilities design in animal settings:

Confidence in preclinical research (PDF): the editors introduce the topic, discussing the ubiquity of hidden variables; of course, noise and vibration are among those. As consultants, one of our design tasks is to minimize the impacts (or at least the hidden-ness) of these parameters.

Interesting Quote: [A variety of] ‘hidden’ variables can affect the robustness of results with mice or rats. Rodent models are susceptible to stress, and vivariums and labs can be stressful environments. Regardless of what disease is being modeled, significant amounts of uncontrolled stress are likely to influence study outcomes.

Introducing Therioepistemology: the study of how knowledge is gained from animal research (PDF): Garner et al. introduce the issue. They touch on what I call an “empathic design perspective” that (at the facilities level) seeks to understand the animals’ experiences and design these laboratory environments accordingly.

Interesting Quote: An implicit assumption […] is that we have controlled everything we need to control, but this cannot be the case—animals see colors we do not, hear sounds we do not, have electrical and magnetic senses that we do not, respond to odors and pheromones that we can’t detect and are fundamentally affected by things we are unaware of.

The role of the IACUC in ensuring research reproducibility (PDF): Silverman et al. review problems related to environmental parameters like noise and vibration and bring up rack/cage vendor differences. I am convinced that significant impacts to the animals occur at the rack/cage-level as much as at the building-level. The implication is that we should be paying as much attention to rack and cage systems as we do to design of the lab building itself. In fact, some of those subtle factors that Silverman discusses ("location of cages in the rack") might actually be related to noise/vibration issues within the rack itself.

Interesting Quote: The macro and microenvironment, including temperature, humidity, noise, vibrations, lighting levels, environmental enrichment, water and food and bedding also are factors that can impact animals physiologically or behaviorally. Even subtle factors, such as the location of cages on the rack and the cage manufacturer may have an impact on the animals.

Aggression in group-housed laboratory mice: why can't we solve the problem? (PDF) Weber et al. discuss aggression, disturbance, and sleep in rodents; this echoes my long-standing suggestion that noise and vibration issues in animal labs might be problems of sleep disturbance as much as annoyance. This has implications for what, exactly, should be our goals in designing and monitoring labs.

Interesting Quote: […] mice are nocturnal and light sensitive, but are kept in brightly lit vivariums and are typically handled or otherwise used in experiments during the light phase, when they should be asleep. A disturbed sleeping pattern can lead to stress, frustration and aggressive behavior. Although cage cleaning is known to lead to flare-ups in aggression, the effects of other forms of disturbance have not been studied.

Laboratory environmental factors and pain behavior: the relevance of unknown unknowns to reproducibility and translation (PDF): Mogil argues for improved standardization. Despite the lament that some parameters cannot easily be standardized, I can’t help but think that we can improve standardization for noise and vibration in lab facilities. If viewed from a “contamination” perspective, then maybe all we have to do is just reduce these environmental stressors to less-than-significant levels.

Interesting Quote: These sorts of findings have led to a discussion as to whether reproducibility in animal experiments would be enhanced by standardization of husbandry and experimental parameters across laboratories. Some have argued for such standardization in the name of sample size reduction, and improving comparability of results within and between laboratories. Others have pointed out that many environmental factors simply cannot be practically standardized (for example, staff, room architecture, noise, tap water composition, locally sourced rodent chow), and that any such attempts would prioritize comparability over the potentially even more important aim of generalizability (external validity).