Horses and Donkeys not being able to be mounted to be tamed

As I was trying to tame a donkey, I would right click on it and it would not mount, it would just buck as if I was on it, and I continued to right click on it and also feed it Wheat but it wouldn't become tame. I also experienced that with one horse. I've also found that sometimes a horse foal or donkey foal will get trapped in the terrain and suffocate without its head being covered.