Other animals stagger about the cage, generally falling head over heels. The animals react feebly to external stimuli and, as soon as they are left alone again, they relapse into their apparently very pleasant dream condition. II, part 2, pp. So far as I know, it is only in dogs that cannabis provokes such a characteristic intoxication pattern. After an injection of cannabis extracts the animals show a negative corneal reflex - i.e., when the cornea is touched, the eyelids do not close.
Difficulties arise in preparing an injectable extract.
The volume injected intravenously is always 0.25 cc per kg of the animal's weight. Only the concentration of the preparation varies. A corneal unit is the smallest quantity of the preparation per kg of body weight that intermits the corneal reflex. It should be noted that the dose of alcohol injected does not of itself reduce the sensitivity of the cornea, and also that this method gives only approximate results. Sensitivity to pain is not reduced.