Grade A
Procedures which cause minor discomfort or low-level anxiety or apprehension for short periods.

For instance: experiments on completely anaesthetised animals which do not regain consciousness; standard methods of euthanasia that rapidly induce unconsciousness (e.g. anaesthetic overdose); taking a blood sample from a superficial vein; injecting a non-toxic substance; skin tests which cause low-level irritation without ulceration; feeding trained animals by a tube passed via the mouth into the stomach; movement of free-range domesticated animals to unfamiliar housing.

Little suffering or noxiousness. Procedures require justification.