A deer in Gothenburg, Sweden has Gnarly cactus. normally referred to as "cactus buck" or "Gnarly buck".
Gnarly cactus is a condition which causes the animal’s antlers to continue growing until they cover its eyes. Normally, a hormonal impulse stirs the bucks to rub the velvet off its antlers every year, and eventually shed them.
When a hormonal imbalance disturbs the shedding of the animal’s antlers, each growing cycle produces more velvet and antler material on top of the previous year’s until they eventually grow over the deer’s eyes, resembling a cactus.
An animal with this condition will have very small or completely undescended testicles. Animals with this condition are not expected to live for a long time. Once the antlers grow over his eyes, the animal will be unable to fend for itself.