Even though it's largely cinematic and fictional, I'm a bit fixated on the legend of the witch that can curse enemies by turning them into animals. Outside of modern pop culture and the like there are ancient myths such as Arachne who was turned into a spider, Psyche and Bloudewedd who were both turned into owls and Lycaon who was turned into a wolf (although these all heavily involved divine intervention). The Odyssey also mentions a witch named Circe who turned trespassers on her island into pigs and other animals. Scottish witch Isobel Gowdie, in her lengthy confessions, also claimed that she and her friends once turned one of the townsfolk into a camel.
Anyway, it made me wonder what the closest thing to it would be in real life. Obviously you can't actually turn someone into an animal, but what if there was a curse that changed their mood and thoughts to match that of a certain animal? For example if you turn them into a rabbit they'd feel unfocused and jumpy, if you turn them into a toad they'll feel restless and cranky, if you turn them into a snake they'll feel threatened and start lashing out at people, etc. Although I'm not sure what the spell needed to accomplish that would resemble.
I don't really curse people, I just find myself musing on this kind of thing. I'd like to hear someone else's ideas on it, what the closest thing in real life would be to an animal-hex, and maybe how you could hypothetically go about casting it.
I don't know of one, but I suppose using the animals fur or a toy representation of the animal in a spell while focusing on the symbolism you are working with. You may think someone was cunning as a fox, but simply using a fox in a spell might translate to being a "sexy fox". I feel it would also be similar as with dream interpretation, what you might hate, another might love.
I do know a number of hexes that use animal parts, like snake skin, or chicken feet [while snake skin I can only think of the positive attributes it's used in, chicken feet can be used to symbolically claw and scratch at someone] you could always try writing a spell and trying to, being sure to observe anything that may happen [but I wouldn't recommend cursing people for experimentation]
Neko is correct. I've personally ever heard of a curse causing an individual to act in an animalistic manner or to act as an animal in general, but there are several hexes you can cast involving the parts of animals. Some even use wasps and spiders to "sting" and "bite" their enemies. The idea behind these kinds of acts is that the abilities of the animal or insect impact the individual much like they would in the real sense. So the claws of a chicken or the sting of a wasp would bring harm, pain, misfortune, etc to your intended target.
I think there may be some very different ways to look at these myths.
For some, these tales seem to be mostly symbolic. Often, the transformation into an animal shows a transformative process in the life of that character, while sometimes it is used to show the perversity and evil nature of the one who changed them. Sometimes, the experience of a loved one who was changed into an animal is what leads to the character development of the others. I don't necessarily mean this just as a plot device. We are, after all, in a forum about magic, and I believe that magic and psychology cross often, especially in cultures where psychology did not yet exist.
I'd say it this way: Consider that sometimes a transformation into an animal is a means for the character in that tale to either experience a mental break, and show this break to the wider audience, or to be debased in some way. Say the tales of people who were turned to frogs, and after some time, they accomplished that which was necessary to ascend back into a human. During the time as a frog, they were debased; frogs have long been reviled, and considered among the lowest of the low. They swim in mucky pools (in many areas, they were often found in open sewers, cisterns, etc.), and eat the very flies which spawn on the excrement. Through this debasement, the person learns a valuable lesson -- often in humility.
For some tales, it seems that the idea of being turned into something was used as a means of inflicting fear. Such rumors were spread of misinformation, and used to teach people to revile those who practiced any sort of witchcraft or magic. What better then, among the lists, than to add that those old tales of cursing people into poop-swimming frogs is true?
Of course, there are still more options. An example can be sourced from the first post, with Isobel Gowdie. Did the people of her area actually see a camel walking around? It would have been quite the sight in Scotland, yes? If not, it seems that in her confession became a permanent record that her accusers would literally believe anything the accused spouted. It really sounds like something completely sarcastic, sort of like, "Yeah? You made potions to make the shepherd's ewes birth winged goats? And what else?" "Oh, I turned that man who scoffed at me into a camel!" "I don't remember any reports of a camel. But a camel, you say?!" *records in notes*