Do you like horses, thats helpful, call an Equine vet an ask them
Well what I got told is you need 5 qualafications encluding maths english and science but they don't have to be a-c they can be any but it will be a lot easier to train if you have a-c
You need to make sure you study horse anatomy so you know the general build-up of a horse. You also need to study equine nutrition because you will be required to know the general diet of the horse in case any illnesses you deal with are somehow related to the wrong diet etc. You also need to have a love of horses to be successful in this profession. Something else I recommend, but is not 100% necessary, is being able to look at any situation through the horse(s)' point of view (The horses involved in the particular situation). This will help ensure that the treatment given to the horse does not upset the horse too much and it will lso give you the knowledge of how to handle the horse when in direct contact (ie. If the horse got a serious injury to the face, it may become head-shy even after the injury has healed, therefore you can handle it accordingly by not touching it's head or giving the horse the impression that you are going to touch it). I am not 100% sure what qualifications you would need, it all depends on your region of the world, however, I recommend you do some research on different universities around your region to estimate which one would be able to give you equine-related qualifications that will help you later in your career.