horses fighting

Question
i have a 20 year old mare.  bought her last summer.  the neighbor of my farm
(i live in town) has many horses and takes care of my horse.  my horse and
her 28 year old mare have been together since last summer.  i few months
ago lori purchased another older smaller mare. the three horses have been
together for a few months.  lori keeps the three horses together in a barn
with a small open pen area.  we have electric heater water.  lori has told me
that she does not want these horses out in pasture in winter because they are
older and she wants to control their diet.  she has also told me that my horse
gets alittle attitude at feeding time and she has been tying her up while the
other two horses eat their hay.  she said there were no problems with this.  
well last thursday morning lori went to feed horses in the morning and my
horse had kicked one of her horses to near death (she put this horse down
the next day) and also kicked her 28 year old mare and she was bleeding cut
and in bad shape.  she probably will leave buy might have a bad shoulder.  a
little to early to tell.  my horse who dished out the punishment has been the
best natured horse i have ever seen.  my kids ride her all the time and she is
the best "kid" horse ever.  have you ever heard of anything like this before?  
should i now be concerned about letting my kids ride this "well natured"
and"loved" horse?  thanks tom

Answer
Tom,
 First off, if she has never shown any aggression toward you or your kids, I wouldn't be concerned about letting them be around her.  The kicking and fighting with the other horses is just natural behavior.  Being that all 3 mares are much older, something must have really gone wrong for her to kick with that much force or determination.  Now, is this the story the barn owner gave you, or was this actually witnessed by somebody, becasue if it happened in the middle of the night, anything could have happened, nobody will ever know, and what is being said is all stipulation.  This older mare could have already had a mojar health issue, and your mare kicking her could have just aggrivated it, as a vet tech, we would see those cases all the time.  With horses and animals, freakish things happen.  I find it very strange that after a year of being in the same place, wth the same routine, and a few months with a new horse, that your horse would just all of a sudden turn into satan, and go on a murder spree.  That is not adding up in my head at all, unless she is having some sort of brain problem that is causing pain, or confucion on her part, but you would see other signs of that, not just one night of strange behavior.  I would ask a few other experts what they think about the situation, and I would not lose any sleep over it, unless the other owner is going to press some sort of legal action, or something.  But I think she should be fine with your kids.

I hope this helps, please let me know if I can help with anything else.

Samantha Brunner