Hi everyone recently got a 15hh warmblood x on loan (5yo). Unfortunately after a week of being great to catch, box etc she has now gone wild. I can't catch her without ears back bucking and cantering off! When she is fed in the morning I now can't get into her stable without her kicking the door and barging her way out of the stable. I have tried ignoring her in the field taking food down to entice her, just spending time with her without catching, tried apples etc calling her, is there something simple I'm not doing or is it a more complicated issue. She is only on loan and at present her owner is coming out to ride her 3 times a week (when her owner is here she acts like a complete baby and is good as gold) really appreciate some advice on this. Thank you.
You say she acts fine for her owner. She plays up bad for you. Simple answer? She doesn't respect you, and has learnt that she doesn't have to. She is showing classic signs of a spoilt, disrespectful horse and you are letting her walk all over you.
If she acted that way with another horse they sure would put her in her place. What are you doing when she acts like this? Nothing? Bribing her with food? Offering her food as a bribe to come in is doing nothing to help you, she's basically giving you the middle finger! To fix it you need to go back to basic and do a lot of ground work. I'm not the best for that so look up some other threads on what you can do. Show her that you need to be respected, that you are alpha, but also that you can be trusted and you are fun to be around
That doesn't mean bribing her with food. It means being a good leader.
As for the bucking in your face and galloping off... Stop it now! As soon as she turns you chase her off. Give her a chance to stop and settle and try again. Every time she turns you make her run. Help her understand that it's easier for her to just stand and be caught. Don't bring her in just to work, bring her in for a groom or a feed.
When handling her be firm, fair and consistent.