356 R. J. Goss 



plained. In other deer, the velvet cannot normallv be shed unless 

 testosterone is present, nor are the antlers lost and replaced unless 

 the velvet has been shed. 



The premature loss of burnished antlers brought about by castra- 

 tion is unquestionablv the result of reduced testosterone. Not only 

 are unilateral castration and cryptorchidism ineffectual (Zawadow- 

 sky, 1926; Jaczewski, 1952), but, according to experiments con- 

 ducted by the author, replacement therapy prevents the shedding 

 of antlers following castration. In these investigations,* 4 deer were 

 castrated in the autumn and injected at operation with 500 mg of 

 testosterone phenylacetate (Perandren)^ in microcrvstalline aque- 

 ous suspension in a concentration of 50 mg per ml. Thereafter for 3 

 months each deer was injected intramuscularly with 100 mg testos- 

 terone twice a week, followed bv three final injections at weekly 

 intervals, the last administered 112 days after the beginning of the 

 experiment. Excluding one animal that died accidentally after 84 

 days of treatment, the remaining 3 deer shed their antlers an 

 average of 151 days after castration, or 39 days after the last injec- 

 tion (Table I). Another 4 deer were similarly castrated, but given 

 25 mg (250,000 lU) of estrogen (Theelin)^ in aqueous suspension 

 (5 mg/ml) at operation, and 5 mg of estrogen thereafter according 

 to the same regimen as above. Antler shedding was delayed an aver- 

 age of 141.5 days after castration, or 29.5 days after the terminal 

 injection. In comparison, 14 control animals castrated at various 

 times between September 24 and April 20 shed their antlers an 

 average of 7 weeks later (Table I). Therefore, both testosterone 

 and estrogen can delay loss of antlers in castrated deer, but 3 to 7 

 weeks after injections of these hormones are stopped, shedding 

 occurs as in castrates not benefiting from replacement therapy. In 

 all cases, new antler rcHeneration occurred after the old ones were 

 lost, regardless of the time of year. These results extend the earlier 



"Experiments were performed on sika bucks (Cerviis nippon) anesthetized with 

 succinylchohne (Anectine; Burroughs-Wellcome and Co.) in doses of 0.6 to 1.2 mg 

 per deer. Anesthetics and hormones were administered subcutaneously or intra- 

 muscularly with automatically injecting projectile syringes shot from a Cap-chur 

 rifle (Palmer Chemical and Equipment Co., Douglasville, Georgia). 



f Samples of Perandren generously supplied by Ciba Pharmaceutical, Inc. 



I Theelin was generously supplied by Parke, Davis and Co. 



