cat unit

cat u·nit

the dose of a drug (per kilogram of body weight of cat), which is just large enough to kill a cat when administered intravenously; was applied in the standardization of digitalis materials.
The minimum amount of a substance (expressed in g/kg) which is lethal to cats when injected intravenously; in practice, the LD50 used to evaluate acute toxicity is usually measured in rats and mice, and less commonly in rabbits and dogs

cat unit

The amount of drug per kilogram of body weight just sufficient to kill a cat when injected intravenously slowly and continuously.