Hi, and WELCOME to the donkey end of the forums from Wisconsin. Congratulations on becomming owned by two beautiful donkeys. Your going to wonder how you even managed to not own one long before this. They are so addicting. You can use a pony bridle with a donkey IF you can find a decent fit with one. I know of alot of people who do use pony bridles, but you also can order a special made donkey bridle but they do cost alot more. I have always used a pony bridle with mine, and have never had any problems. But, if you want to measure your donkeys head..here is how you would go about that...LOL..
Hope this kind of helps you. Measure from where the top of the bit ring would sit (above the corner of your donkey's mouth), up across the top of his head (behind his ears), and down to where the top of the other bit ring would sit (above the corner of his mouth on the other side). Compare this measurement with the size of the bridle - length of the cheek straps and crown piece (over the top of the head).Next measure your donkey's throatlatch. Start at the top of his head, behind his ears (where the bridle would sit), measure down under his throat and back up to the same point above his head. Add a few extra inches. Compare this with the size of the throatlatch strap on the bridles. This is one of the two places where I find most bridles are too small. So make sure that a pony bridle one is big enough.The third measurement to get is the brow band size. Measure from behind and slightly below your donkey's ear, around across the front of his forehead, and back to behind and slightly below the other ear. Compare this measurement with the size of the bridle's brow band. This is the second place that I find most bridles are way too small. You want the brow band to be big enough so that the bridle sits comfortably behind your donkey's ears, and not pulled up so tight that it is rubbing on the backs of his ears all the time! It really helps to take a flexable ruler along to your tack shop to measure what they have in stock.
Corinne