Since 1820, when a bear was drugged
with a mixture of honey
and strong spirits
have been used to subdue
Oral administration of these drugs proved difficult, however. A breakthrough came in the mid fifties when darts were used for the first time. Initially these darts bore neuroleptic payloads, which could be dangerous for the ranger and animal alike, as the doses were largely uncertain and the effects more so.
The use of opiates became a more successful option.
A significant breakthrough was made in 1960 by Harthoorn. Working with the ranger team of the Natal Game and Fish Preservation Board he pioneered the use of a mixture of morphine or synthetic morphine, hyoscine, and various tranquillizers. The development and use of newer, extremely potent synthetic and semi-synthetic opioids, cyclohexylamines, phenothiazine derivatives, and alpha-2-agonists, then followed.
Drugs used for the immobilization, capture, and translocation of wild animals
- G.E. Swan
Among the semi-synthetic opioids researched were derivatives of Tetrahydrocannabinol or cannabis, commonly used as a recreational or spiritual drug in many cultures and countries.
As such, relatively speaking, the exact amount of spliffs, or cannabis cigarettes required to incapacitate a rhinoceros or other large undomesticated animals has been researched but the exact quantity is largely a mystery.