The Procedures

What is done to beagles in laboratories — every major procedure type

Overview Toxicology Safety Pharm ADME/PK Device Testing Newer Areas Study Design

What Necropsy Involves

Necropsy is the animal equivalent of autopsy. After euthanasia by lethal injection (pentobarbital), the body undergoes systematic examination. Organs are removed, weighed, and sectioned. Tissue samples are prepared for microscopic examination — histopathology. Pathologists examine 40+ tissue sites per animal for cellular damage, tumors, inflammation, and organ-specific toxicity.

Why ~95% of Dogs Are Killed

Key Finding

This is the central fact: approximately 95% of beagles used in research are killed not because euthanasia is convenient, but because the data regulators require comes from tissue. A living dog cannot yield liver sections, kidney weight ratios, or microscopic slides of heart tissue. OECD TG 409 specifies terminal necropsy as the endpoint. The study design assumes death.

Full organ examination includes:

BrainHeartLungsLiverKidneysGI tractReproductive organsLymph nodesBone marrowEyesSkinSpleenAdrenalsThyroidPancreas

40+ tissue sites per animal. Histopathology slides prepared and examined by board-certified veterinary pathologist.

Rehoming Rates

0.4%

UK rehoming rate

44 of 10,456 dogs (2015-2017)

~39%

EU reuse rate

Delays rather than prevents death

Not published

US rehoming rate

No federal requirement to report

FELASA Position

The Federation of European Laboratory Animal Science Associations supports rehoming in principle but identifies a welfare constraint: “rehoming at all costs” can cause harm if dogs are placed in environments they cannot adapt to after years in a laboratory. Dogs that have never experienced outdoor environments, household noise, or human companionship outside of handling may suffer without extensive rehabilitation.

Methodology Caveat

The issue is not cruelty for its own sake. It is that the regulatory system was designed with necropsy as the assumed endpoint. Changing the endpoint requires changing the data requirements, which requires changing regulatory standards, which requires international harmonization across OECD, FDA, EMA, and national agencies. That process is slow.