====== Animal Research ======

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

===== 🔬 What is Animal Research? =====
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

===== 🐁 Why Are Animals Used? =====
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

===== 📉 Common Species Used =====
  * 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

===== ⚖️ Ethical Considerations =====
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:
  - '''Replacement''': use non-animal methods when possible
  - '''Reduction''': use the minimum number of animals necessary
  - '''Refinement''': minimize suffering and improve conditions

===== 📚 Regulations and Oversight =====
  * '''EU''': Directive 2010/63/EU
  * '''USA''': Animal Welfare Act; IACUC review
  * '''Spain''': Real Decreto 53/2013

===== 🧠 Example Study: Brain Changes in Captivity =====
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.