The unicorn is an equine animal with a horn on its forehead. This horn gives them a dressage bonus.
To be able to cover a unicorn, both parents must be unicorns of the same breed and you must have a unicorn covering session available.
If you follow all of these rules, you have a one in 5 chance of getting a unicorn.
You must wait at least 10 hours after a female unicorn conceives to cover them for the first time. You must also wait for a minimum of 10 hours between 2 coverings of the same unicorn.