How many animals, and what's done to them?
Short answer: An estimated 192 million animals a year worldwide. The methods include dripping chemicals into rabbits' eyes and dosing animals until half of them die, often without pain relief.
An estimate across 179 countries, the true figure is unknown because much testing goes unreported.
Taylor & Alvarez (2019); AAVS
The objection
“It’s a handful of mice in a clean lab, surely. People exaggerate this stuff. How bad can it really be?”
The answer
Not a handful. The most thorough estimate, standardising the figures countries do publish and modelling the ones that don’t, put global animal use at around 192 million animals in a single year (Taylor & Alvarez 2019). That’s a careful estimate across 179 countries, and the authors are clear it’s likely conservative, because much testing is simply never reported.
As for what’s done, two long-standing tests show the texture of it. The Draize test drips a chemical into the eye of a restrained, conscious rabbit with no anaesthetic, then scores the redness, ulceration and corneal damage for up to 14 days (ScienceDirect; AAVS). The cornea is among the most nerve-rich tissue in the body, so the pain is considerable, and the restraint stops the animal even rubbing its eye.
The LD50 (“lethal dose, 50%”) test feeds animals rising doses of a substance until half of them die, recording tremors, convulsions, bleeding and laboured breathing on the way. The result it records is a body count.
And across the board, pain relief is frequently not required and frequently not given, because analgesics might interfere with the result.
These are not historical curiosities. They remain in regulatory use. So when you picture animal testing, picture the real scale and the real methods. The clean-lab image is a marketing photograph; the eye, the dose and the death are what the work actually involves.