The Legacy of the Institute for Laboratory Animal Research
For nearly seven decades, a little-known institute has quietly shaped the way scientists work with animals to advance human and animal health.
In the early 1950s, biomedical research using animals was in its infancy—characterized by varying standards of care and experimental approaches that lacked uniformity across laboratories. Recognizing the need for scientific rigor and ethical responsibility in this growing field, the National Academy of Sciences created the Institute for Laboratory Animal Research (ILAR) in 19531 .
Just as important scientific discoveries have stories behind them, so too does the institute that helped ensure those discoveries were made ethically and reproducibly. In 2022, ILAR concluded its remarkable journey, transitioning into the Board on Animal Health Sciences, Conservation, and Research (BAHSCR), but not before fundamentally transforming the landscape of laboratory animal science1 .
ILAR's creation came at a pivotal moment in scientific history. The post-World War II era saw unprecedented growth in biomedical research, but this expansion brought challenges in standardizing animal care and use. When ILAR first opened its doors, research was predominantly conducted with larger animal species, but the institute would witness a dramatic shift toward smaller species like mice, fish, and rats over the coming decades1 .
Throughout its existence, ILAR's mission remained constant: to improve the humane care, use, and management of animals in research while ensuring scientific validity. The institute served as an honest broker, seeking consensus among researchers, veterinarians, ethicists, and policymakers. This neutral positioning allowed ILAR to develop guidelines and standards that balanced scientific progress with ethical responsibility1 .
One of ILAR's most significant contributions was the development and promotion of the "Guide for the Care and Use of Laboratory Animals," which became the gold standard for animal research facilities worldwide. This comprehensive document provided research institutions with evidence-based guidelines for everything from cage space requirements to veterinary care, dramatically improving animal welfare and research quality.
Major Developments: Institute established in 1953
Key Contributions: Laid foundation for standardized animal care
Major Developments: Research expansion era
Key Contributions: Developed early guidelines for animal care and use
Major Developments: Growth of genetic engineering
Key Contributions: Addressed ethical challenges of new technologies
Major Developments: Rise of reproducibility concerns
Key Contributions: Emphasized statistical rigor and experimental design
Major Developments: Transition to BAHSCR
Key Contributions: Expanded mission to include conservation1
In the early 21st century, biomedical research faced a sobering revelation: many published findings, particularly those involving animal models, could not be reproduced. Freedman et al. estimated in 2015 that the cumulative irreproducibility rate in preclinical research was approximately 50%, with inadequate study design and data analysis identified as major contributing factors6 .
Irreproducibility Rate in Preclinical Research
Framework: Reduction, Replacement, Refinement, Responsibility
Target Statistical Power for Animal Studies
This "reproducibility crisis" represented both a scientific and ethical emergency in laboratory animal research. Each irreproducible study represented not just wasted resources, but the unnecessary use of animal lives. ILAR recognized that poor experimental design violated the core principles of animal welfare—particularly the 4R framework of Reduction, Replacement, Refinement, and Responsibility6 .
ILAR responded by championing better statistical practices and experimental design. Through workshops, reports, and its influential ILAR Journal, the institute emphasized that statistical power—the probability that a test will detect a true effect—should be a primary consideration in animal studies. Underpowered studies not only risked missing true effects (false negatives) but were also less likely to be reproducible even when they found statistically significant results6 .
To understand how ILAR's guidance transformed research practices, consider their advocacy of simulation studies for power analysis—a method that became increasingly important for complex experimental designs where traditional power calculations were insufficient6 .
Simulation studies work by creating data using computer-generated random number sampling from known probability distributions. The process involves several key steps6 :
Researchers define clear null and alternative hypotheses before beginning experimentation.
Control animal data from previous studies or databases provides baseline parameters.
Researchers examine empirical distributions to propose appropriate probability distributions.
Parameters for each experimental group are defined based on the research question.
This approach allowed scientists to determine adequate sample sizes needed to achieve desired power (typically 80%) without using excessive animals—exemplifying the "Reduction" principle of animal welfare6 .
A compelling example comes from toxicology research, where scientists used simulation to determine the power of Jonckheere's trend test—a statistical method for evaluating dose-response relationships in organ weight data. By simulating data based on historical control information from the National Toxicology Program, researchers could validate their statistical approach before any animals were used6 .
These simulations revealed that many traditional sample sizes were either underpowered (risking false negatives) or overpowered (using more animals than necessary). By optimizing experimental designs through simulation, researchers could maintain statistical rigor while aligning with ethical animal use principles6 .
| Term | Definition | Importance in Animal Research |
|---|---|---|
| Statistical Power | Probability a test detects a true effect | Ensures animal use yields reliable results |
| Type I Error (α) | False positive rate (typically set at 5%) | Controls likelihood of falsely claiming an effect |
| Type II Error (β) | False negative rate (often targeted at 20%) | Affects probability of missing real effects |
| Effect Size | Magnitude of a change or association | Determines biological significance beyond statistical significance |
| Simulation Studies | Computer-generated data to test statistical methods | Allows power analysis for complex designs without preliminary animal use6 |
While ILAR began with a focus on laboratory animals, its vision expanded significantly over time. The institute's work increasingly addressed wildlife, biodiversity, and conservation issues, recognizing that the principles of humane animal use extended beyond traditional laboratory settings2 .
Initial focus on standardizing care and use of animals in research settings.
Expanded scope to address conservation and non-model animal species2 .
This expanding scope was evident in ILAR's later publications, which included proceedings on topics like "Animal Welfare Challenges in Research and Education on Wildlife, Non-Model Animal Species and Biodiversity"2 . The institute also contributed to consensus reports such as "Biodiversity at Risk: Today's Choices Matter," demonstrating its commitment to the broader ecological context of animal health and welfare2 .
This evolution ultimately led to ILAR's transformation in 2022 into the Board on Animal Health Sciences, Conservation, and Research (BAHSCR), reflecting a more comprehensive approach to animal sciences that includes conservation alongside research1 .
| Resource Type | Specific Examples | Function and Importance |
|---|---|---|
| Animal Models | Inbred, outbred, mutant, genetically engineered strains | Provide specific characteristics for studying diseases and treatments7 |
| Database Resources | LasDB (21,596 mouse strains), IMSR, ILAS records | Enable researchers to locate and share animal models globally7 |
| Statistical Tools | Simulation software (R, Python), power analysis modules | Ensure robust experimental design and reproducible results6 |
| Alternative Methods | Organoids, organs-on-chips, computer simulations | Reduce animal use while maintaining research quality8 |
| Guidance Documents | ILAR Guide, consensus reports, workshop proceedings | Provide ethical and methodological standards for the field2 |
The transition from ILAR to BAHSCR in 2022 marked not an end, but an evolution. Over its 69-year history, ILAR had fundamentally shaped how scientists approach animal research, embedding ethical considerations into the very fabric of experimental design1 . The institute championed the idea that good science and ethical science are inseparable—that well-designed studies with proper statistical power are both more humane and more likely to produce meaningful, reproducible results.
Brought together diverse stakeholders to find common ground
Balanced scientific progress with ethical responsibility
Promoted robust experimental design and reproducibility
Perhaps ILAR's greatest achievement was fostering a cultural shift in the scientific community. By serving as a neutral convener and evidence-based resource, the institute helped move the field from seeing animal welfare and research quality as competing interests to recognizing their essential interdependence.
Today, as BAHSCR builds on this legacy, ILAR's influence continues to be felt every time a researcher conducts a power analysis before an experiment, consults the Guide for the Care and Use of Laboratory Animals, or chooses a simulation study over preliminary animal testing. In the ongoing effort to advance knowledge while respecting life, the institute's history offers both a foundation and a roadmap for the future.
| Publication Type | Purpose | Example Topics |
|---|---|---|
| Consensus Study Reports | Document evidence-based consensus on study questions | Nonhuman primate models, toxicity testing methods, laboratory dog use2 |
| Proceedings | Chronicle presentations and discussions from workshops | Animal welfare with wildlife, human-animal interactions in research2 |
| Rapid Expert Consultations | Provide timely input on narrowly focused topics | Reviews of VA monographs on service dogs for PTSD2 |