What would make a mare cross fires all the time. We will be going alone fine and then she cross fires in the hind end. She will do this when I’m just working her in the round pen without me on her.
Have you tried loping straight lines? Does she do it then?
ETA: I have a new gelding that cross fires only in the round pen... He is green (broke as a 2 year old then turned out to grow) and does not know how to use his body properly yet. He lopes straight lines fine but cannot balance himself properly in a circle yet.
Mine is also 5 :)
I guess I am not much help then... I was told to just keep helping him build his muscles and confidence and he would start getting it. I have had him about 3 weeks and he is already better in the round pen (on days that I decide to lunge him) he will go a lap or so correct before he crossfires.
At two years old, it is usually just because they have not yet developed the strength in their hind end to hold a lead while in a circle. They switch back and forth trying to get comfortable, because they tire easily. As they build muscle they will be able to hold it longer and longer.
If your horse is older, has been riding a while, and has the muscle development it is usually indicative of soreness.
Depending on how old she is she could just not have the strength built up to be able to hold a lope for a period of time without having to cross fire, or there's a pain issue that should be addressed by your vet and chiropractor.