biting & charging mare - no patterns

Question
 My husband bought a 13 year old mare a few months ago.  She will take a snack from your hand but has not been one that nibbles playfully. If she wasn't taking something to eat, she didn't seem to see a need to have her lips on you. Until she decided otherwise.
 She has snapped her teeth in the direction of my 6 year old daughter's face when my daughter was standing about 3 feet in front of her (thank God she didn't bite her!). The mare nipped the arm of my daughter and her friend when they were standing at the mare's shoulder area petting her - nipped hard enough to make purple bruises. One evening she stood perfectly still in the open pasture while I brushed her all over and talked to her. She seemed perfectly content. Her ears weren't back or anything. When I finished brushing her, I stepped forward so that my chest was near her left front breast-shoulder area and was stroking both sides of her neck as I continued talking to her. Before I knew what happened, she hit the side of my head so hard with her teeth (with her mouth wide open)that she knocked flat on my back. She began pawing. I didn't know if she was planning to stomp me so I immediately began kicking my legs up in the air as I scooted myself backwards & through the gate.
 Today as we were feeding, we were one bucket short of having all of the horses fed. (Of course it happened to be this mare who was left waiting for her food:-( I happened to be standing near the mare as my daughter went to get the bucket. Again, we were in an open field. (We just moved here and have no individual stalls yet.) I know the mare was impatient for her food. I was talking to her. Should have known better than to be anywhere around her, but I guess I stupidly let my guard down and stood too close to her. I suppose her manner of telling me to shup up and bring on the grub was to act like she was going to nip me on my jawbone. Not anywhere as violently as the previous time, but a nip, just the same. I reached to grab her nose. As I began to grasp it, she began bouncing on her front legs an shaking her head, which pulled her nose from my hand. Her front legs began going higher and higher as if she was going to rear up at me. Again, I had wound up between her and the fence. (How dense am I?) By that time, my daughter arrived with the feed, handed it to me over the fence, and I was able to pour it into the mare's feed bucket which was close by. That ended the episode of today.
 We've looked for a pattern to see if this might be related to her monthly cycles. Not really sure about that. I know this last episode had to do with the food issue, her being spoiled, and me not being in control.
 Since we aren't able to pin down a pattern for this behavior, how can we address it? Except for the food incident, the others have come from out of the blue as far as we can tell.
 One pattern we HAVE identified: She tries to bite other horses if they get ahead of her in anything other than a walk on a trailride.(Very competitive). I wouldn't doubt that she might bite the leg of the rider of the other horse if she was in a position to do so.
 The previous owner said he saw none of this behavior when he had her. He's a friend of ours who knew our kids would be around this horse and we don't think he would have been untruthful about this. He buys and sells horses and had only had this mare for a few months. She is one he had been riding personally.
 She's one of the best riding horses (most cooperative, responsive, even tempered) we have except for this horrible, dangerous vice. HHHeeeeeellppppppppp!!!!!!!!!!!!!!!

Answer
Angela,

You are gonna have to get some backbone girl!  This mare is walking all over you and everyone else.  You need to put your foot down and let her know in no uncertain terms that this is unacceptable behavior.  

There are times, and this is one of them, that the most effective method I can tell you may not be the one you want to hear.  But it will work.  She's obviously become an alpha mare and is asserting her dominance over you.  That's ridiculous, you feed her!  You need to keep a halter on her, all the time.  Rather than cringing away, grab her halter, give her a couple of good, strong yanks and YELL at her!  Let her know in no uncertain terms that you simply will NOT TOLERATE this behavior.  If that doesn't get her attention ram your knee into her side in the girth area.  Hang onto her head all the time.  You have to get mad!  Turn into her worst nightmare!  If she yanks away from you let her go so she can think about this.  She has gotten entirely different results than before.  Keep on your guard and repeat as needed until she gets the hint.  Some horses take longer than others.  

If it is tied into her cycle, once you get the behavior corrected you may want to investigate an herbal mix to feed her to help with her PMS!  You may well have to experiment with several different combinations of herbs to find what works for your mare.  I can refer you to an excellent equine herbalist who can work with you to figure out what your horse needs if you can't find a suitable mix.  It will take a while for the herbs to work but over time can make a huge difference in your mare.  Is she now kept in a mixed herd of mares and geldings or possibly the only mare in the group?  If she's the only mare she immediately became a queen as far as the herd was concerned.  Otherwise she may have asserted dominance over other mares and hence made herself lead mare.  

As far as the nonsense on the trail you have to do the same thing.  Make her aware, in no uncertain terms, that you will not tolerate that behavior.  Period.  Yell at her, use your legs, I've smacked my horse on the neck as well as sharply pulling the head away.  If riding next to another horse I have light, full contact with the mouth all the time and keep the head straight in front.  Any deviation is corrected immediately.  

You've just been too nice to her, that's all.  Put her in her place and she'll be fine.  When you're working with her grooming, etc. have a lead line on her, even in the field, and hold it all the time.  Any problems and you've got the line to shank her with and it'll be a lot harder for her to get away.  Once she realizes you're the boss I think you'll find she'll be back to her old self.  

Let me know if I can help you any more.

Lyn