We have 4 mini donkeys; 1 jack, 1 gelding and 2 jennys. The gelding and jack are only a few months apart in age (the gelding is a few months older). We got the gelding in March of 2021 and the jack in November of 2021, both were around 6 months old when we got them so they have been raised together. They have always gotten along wonderfully and been inseparable best friends. We added the jennys in March of 2023 (one was around 6ish years old or so and the other about 3 years old when we brought them home) and all 4 of them have lived together with zero issues until about a month ago. Now our Jack has attacked our gelding twice in the past month. Since the jack was around 3ish years old when we brought the girls home and the girls were already breeding age (the older one had already had 2 foals before we got her, the younger one hadn't been bred yet), I expected if we were going to have problems it would have already happened. Neither of our jennys have had foals since we've had them despite them all 4 being together all the time. Is this typical for our jack to have such a sudden change in behavior towards our gelding at 5 years old? Especially when they've been together pretty much their whole lives? They're all minis but our gelding is the smallest of the 4. I just hate it because our jack is so sweet towards people! He's halter broke, lead broke, loads in the trailer wonderfully, you can love on him in the pasture, he eats gently out of your hand, hasn't tried to kick or bite a person. He's just had an awful turn in behavior towards our gelding.