If you’ve been observing the Persian fallow deer recently, you certainly will have noticed that one of the antlers of the oldest deer is growing downwards and distorted. We don’t know why this is happening (perhaps because of a traumatic injury at the end of the previous breeding season), but as a result two things have occurred.

One is clear and connected to the bloodstream: in a normal antler, high arterial blood pressure forces the blood up the antler, while the venous blood simply flows back downward with gravity. However, in the downward-growing antler the returning venous blood has difficulty in pushing the blood upward again, causing blood clots around the bony part of the antler. The second, and more interesting, thing is that the antler hasn’t developed branches but has grown as a single mass. This may have resulted from the cells experiencing an “orientation” problem in space. 

We now have three possibilities:
1. To surgically remove the antler. Antler tissue is the fastest growing tissue in the animal world and has large blood vessels; surgery to remove it has many potential complications, including anaesthetization, infection and uncontrollable blood loss.
2. Testosterone injection to stop the antler growth and speed up its shedding. In nature, at the height of the breeding season, testosterone secretion is at its maximum and antler growth ceases. At this stage the velvet (external tissue covering the antler) begins to peel, and shortly afterwards the antlers are shed.
3. Wait and see what happens….. In the meantime the deer doesn’t seem to be suffering from this abnormal growth: he is eating and behaving normally; and, as we are a research institute – and the phenomenon is very interesting – it is logical to wait, observe and monitor development. When the antler eventually sheds, it will be donated to the museum.

It will also be interesting to see how the antler grows next year. In previous years the antlers of some individual that were sick during the period of antler growth were less developed than in healthy individuals. The antlers thus indicate not only age but also signal their owners’ state of health.