Animal Research

'Animal research' involves the use of non-human animals in scientific experiments to understand biological systems, diseases, and the effects of treatments.

Animal research is conducted to study:

• Biological systems (e.g., neurobiology, physiology)
• Disease models (e.g., cancer, Alzheimer’s, infections)
• Drug development and safety testing
• Behavioral and psychological processes

Reasons for using animals in research:

• Biological similarity to humans
• Short lifespans and rapid reproduction (ideal for generational studies)
• Some studies are unethical or impossible in humans
• Controlled environments reduce confounding variables

• Rodents (mice, rats): genetics, cancer, neuroscience
• Primates: infectious diseases, brain studies
• Zebrafish: developmental biology, toxicology
• Fruit flies and nematodes: aging, genetics
• Pigs, dogs, cats (less common): organ studies, surgical techniques

Animal research raises important ethical issues:

• Animal suffering and welfare
• Scientific necessity and justification
• Use of alternatives (in vitro models, simulations)
• Oversight to ensure humane treatment

The '3Rs principle' guides ethical animal research:

1. 'Replacement': use non-animal methods when possible
2. 'Reduction': use the minimum number of animals necessary
3. 'Refinement': minimize suffering and improve conditions

• 'EU': Directive 2010/63/EU
• 'USA': Animal Welfare Act; IACUC review
• 'Spain': Real Decreto 53/2013

A recent study on the common shrew (Sorex araneus) showed that:

• Seasonal brain size changes remain intact under semi-natural captivity
• However, captivity increased activity and reduced learning motivation
• Results suggest chronic stress in captivity, which can bias experimental outcomes

Conclusion: Even well-controlled captive environments may affect research results and must be accounted for in experimental design.