Every year someone kills what they think is a monster buck, but it turns out to be a doe with a nice rack. This year is no exception. The velvet doe that is currently making its round on the internet was killed in Tennessee’s first ever velvet antler season.
707 Deer processing posted photo’s of the velvet doe killed by Bryan Williamson and it went viral.
Many people have asked what causes a doe to grow antlers. Well here is the answer.
An antler doe is cause by a condition called Freemartin Syndrome. It occurs when a female twin(XX) acquires the male (XY) component in utero by exchange of some cellular material from a male twin, via vascular connections between placentas. In most cases the freemartin is rendered sterile. Most of what we know about the condition comes from cattle where it seems to be more common then with deer.
According to Wikipedia:
In most cattle twins, blood vessels in the chorions become interconnected, creating a shared circulation for both twins. If both fetuses are the same sex this is of no significance, but if they are different, male hormones pass from the male twin to the female twin. The male hormones (testosterone and anti-Müllerian hormone) then masculinize the female twin, and the result is a freemartin. The degree of masculinization is greater if the fusion occurs earlier in the pregnancy – in about ten percent of cases no fusion takes place and the female remains fertile.
The male twin is largely unaffected by the fusion, although the size of the testicles may be slightly reduced. Testicle size is associated with fertility, so there may be some reduction in bull fertility.
Freemartins behave and grow in a similar way to castrated male cattle (steers.)
So there you have it. Over all it is a very rare condition and makes for quite the conversation piece.