Minecraft wiki entry for Farm_Monsters, associated text: A hostile variant of the wolves was later added in Minecraft Earth, the skeleton wolf.
A hostile variant of the chicken was later added in Minecraft Dungeons, being the mount of the chicken jockey.
In the April fools update 2.0 there was a feature which made chickens neutral. This meant they would attack you if you hit them.
All the farm monsters are based on minifigures made by Matel which in turn were based on the animals in the Halloween Edition mash-up pack.
Despite donkey robot and the mutant squid having a minifigure, they don't appear in the mini-series but are from the Halloween Edition mash-up pack.
This is the same for other minifigures that were Halloween themed except for the Enderall, the Well Wisher, Cropsy and the Black Widow Spider.
The hostile chicken does have a Halloween themed skin resembling a gray rat in the mash up pack, but it wasn't ever added to the series or made into a minifigure.