Is it possible for animals to be transgender?

It's hard to see why this undercover approach would offer an advantage in a species in which males gain mates by showing off. It's possible that drab males hanging around the edges of a lek site can find mating opportunities with females by getting in between showier males and their conquests. read more

So animals cannot have gender dysphoria or be transgender in the true sense of the word. However, apparently they CAN have gender reassignment surgery if there is a physical reason to do so. One of the answers below mentioned Gertie the hen who turned into Bertie the rooster through natural hormone changs, no outside intervention. read more