Here's some photo's from a camera placed near our protein feeder at our deer lease. The "spike" buck in the picture suffers from a condition called "cryptorchidism". (Other animals, such as horses, can also have this condition) The condition entails the testicles either being extremely small or in often cases, still within the gut cavity. The resulting deer are usually sterile (the testes need to be outside the body for proper sperm production) and have abnormally low testosterone levels. The low testosterone levels is what leads to the abnormal antler development. The antlers will typically retain the velvet, have poor branching and be brittle because of being poorly mineralized. In other cases, the deer will never lose his antlers and they may become abnormally large and thick.
We've been seeing a fairly large percentage of cryptorchids at our deer lease and I've been talking to some wildlife biologists about it. Essentially, they don't understand what causes it, but believe that it might be due to certain plants that contain "phytoestrogens" that affect testicular development. Statistical data seems to indicate an increase in the condition during times of drought or other stress on the native vegetation. During these times the deer may be forced to browse on secondary food sources that are causing the problem.