What ethical concerns are raised by using animals in scientific and medical experiments?

The use of animals in scientific and medical experiments raises significant ethical concerns centered on the tension between scientific progress and animal welfare.1

A primary ethical issue is whether it is morally justifiable to inflict pain, suffering, or death upon sentient beings for human benefit. Critics argue that because animals are capable of experiencing distress, they deserve protection from harm. Furthermore, the lack of consent from animal subjects is a fundamental moral concern, as they cannot agree to participate in research.1

Additional concerns include:
* Necessity and Reliability: Opponents question the scientific necessity of animal models, arguing that many experiments are flawed or could be replaced by alternatives like computer simulations, cell cultures, or organ-on-a-chip technology.12
* Cruelty and Inhumane Treatment: Critics point to practices such as force-feeding, deprivation, and the infliction of wounds, noting that many animals—such as mice and rats—are not covered by the Animal Welfare Act.2
* Species-Specific Ethics: The use of animals with high cognitive and emotional complexity, such as primates and dogs, is particularly controversial.1

To address these issues, the "three Rs" principle—Replacement, Reduction, and Refinement—is widely used to minimize suffering and limit animal use.314