We appreciate the concerns of Atkinson et al. regarding our paper (Alibhai, Jewell & Towindo, 2001), and will try to give reassurance that these are unfounded.
With regard to the drugs used, Atkinson et al. are incorrect in stating that all the agents used in combination with M99 were alpha-2 adrenoceptor agonists. Azaperone is a butyrophenone neuroleptic sedative (Hall, Clarke & Trim, 2001). Whether ACP or another sedative agent was used in combination with etorphine hydrochloride, the risks we have discussed remain valid since the most potent and potentially dangerous is the opioid etorphine, which is used for wildlife immobilization in a high dose to produce an anaesthetic rather than analgesic effect (Branson, Gross & Booth, 1995). The stresses involved in the capture circumstances are very likely to carry a further risk for the pregnant rhino.