I am very surpised that anybody is making excuses for this mare's behavior and the instructors lack of judgement. The OP could have been seriously injured several times in this one LESSON!!! I guess that I am surprised that anyone could suggest that this is a profitable learning experience. I took the original post apart so you could read it AGAIN.
I had a riding lesson yesterday...when I got to the stables I was on a mare called Nelly...I got a brush and started to brush her. She started being fidgety and then she bit me.
If it's hormones, there should be a calendar with days circled in red when this mare's in heat. I TAKE THIS BACK!! When my 13 yo mare is in heat she wants to love on everybody. How about the stable gets a few more like her?
Then I tried to pick her feet out. I lifted her front leg up and managed to pick it out but then she stamped the leg down. A girl who helps out at the stables was walking past and she said that I should just leave the rest of her feet because Nelly is sensitive.
SHe is learning to groom and tack up and the lesson horse refuses to have the feet picked out?
Then my instructor said that she would tack her up for me because Nelly bites and plays up when being tacked up.
She has learned how to tack up, it isn't a matter of a different type of saddle (I own 3 types and they girth up differently, but this was not the case.) FIRST red flag.
I had to stand about 5 meters away while she was being tacked up because she also kicked.
SECOND red flag. I would have demanded a safe mount, or my money returned at this point.
I was getting a bit nervous about getting on her because I am not an experienced rider ... I was assured that she is fine once someone is on her and that they use her on novices.
The stable KNOWS that this is a dangerous horse and are making excuses.
THIRD red flag.
...she refuses to stand still and starts spinning around.
FOURTH red flag.
It seemed like everyone was having a go at me for not stopping her.
You really want to ride with these people?!?!?
(E)ventually she stopped but then took to trying to eat my arm...
I'm wracking my brain trying to figure out which of the 30+ horses I've owned enjoyed eating my arm...
Eventually when it was my turn to get on her, my instructor took her over to a fence and made her face it so that she could not walk off, and them told me to grab the mounting block and get on her as quickly as possible.
FIFTH red flag. Good lesson horses stand still during mounting/dismounting. This is basic.
Once I was on her she took off, and I gathered up my reins and tried to get her to stop. The more pressure I put on the reins, the faster and more agitated she was. Because she was refusing to stop I joined the back of the ride and my instructor adjusted my stirrups while I was walking.
SIXTH red flag. I don't know that I could adjust somebody else's stirrups WHILE they were walking the horse.
I was told that she does not like it when the reins are too short so I should give her rein, but then she kept going to fast and when I pulled on the reins slightly that didn't do anything but I did not want her to buck or anything because I had the reins too tight. This is all at walk, and when we move into trot it gets even harder. I try to slow her down and she doesn't, and is nearly crashing into the horse in front and my steering is rubbish because I am stressed out about her being to fast.
SEVENTH red flag. I think the OP KNEW something bad was about to happen.
Then when I've been trotting for a few minutes, she suddenly rears a bit and then bucks me off! My instructor said it wasn't anything I did and phones someone to go and get a horse called Monty for me to ride of the rest of the lesson. I was a bit shocked as I have never been bucked off before (but I have fallen). I then here my instructor mentioning to someone that the saddle has slipped forward and was a bad fit. Could that be the reason for her bucking?
EIGHTH red flag. Oh, yeah, I remember all of my Hunt-Seat lessons when my lesson horse bucked me off and "I learnt how to ride better."
I have been bucked off (by my horses and by a few others owned by somebody else), and most of them resulted in a few bruises. One time I broke my humerous. (My horse, so no one else to blame, the horse was inexperienced and standing next to a cannon going off, which will probably NEVER happen to you.)
I do not suggest that somebody should not give this abused horse a 2nd chance. Green + Green (or abused) = black & blue and sometimes a hospital stay