Mare has become aggressive towards other horses

Wagtail

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We have a lovely WB mare at our yard who used to be the easiest horse imaginable with others. She was 5 when she came here and is now 12. Yesterday, she ran down, cornered and repeatedly kicked my 3 year old filly with absolutely no provocation. She had been in the next paddock to her for two weeks and all seemed well. Bit of background:

She used to be subordinate to, but adored my old mare who I lost last November.

She used to be kept happily with my mare, a gelding who was PTS last November, my gelding and her now two year old foal.

This winter she has therefore lost two horses that she was close to and has been separated from the other two in the herd because they were going out 24/7 in the winter and she is in work and it was not practical for her owner to keep her out too. But she has had contact over the fence with them every day.

Last December I bought my new filly. The mare was in the sand turnout when she first saw her as I had taken the filly into the arena next to the sand turnout for a leg stretch. The immediate reaction of the mare was to repeatedly rush the fence and squeal and try to kick the filly. I had never seen this behaviour in the mare before.

We also tried to pair her off with a new gelding by introducing them for a week over the fence before putting him in with her. She kicked him badly when he tried to approach her, so they were separated.

But this attack on my filly was just awful and so aggressive. Even when I was trying to catch the mare she was avoiding me and seeking out my little filly in amongst the other two horses (my gelding and her two year old son). She was not aggressive to them, just my filly.

So what could make her suddenly change into such an aggressive horse? She used to be so laid back and we could put her in with any new horse to settle them into the yard. Now I am having to keep her separate. I am too scared even to make her a paddock with electric fencing in case she breaks through and gets to my little filly. At the same time I feel sorry for her because she is on her own (in the sand next to the paddocks), but dare not risk the other horses.

She is lovely with people still.
 
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Maybe she just doesn't want new horses in her space, I would leave her with the gelding and her son, and put your filly with someone else.

Like people they don't all get on, annoying and slightly difficult but best to manage it rather than end up with an accident
 
Maybe she just doesn't want new horses in her space, I would leave her with the gelding and her son, and put your filly with someone else.

Like people they don't all get on, annoying and slightly difficult but best to manage it rather than end up with an accident

Sadly, there is no one else my filly can go out with at present. I only have two other geldings here. One is 8 years old and was only gelded 9 months ago, the other is very very interested in mares, so I think they would fight over her. I have just found some wounds on my gelding too, so he must have got a kick as well, though I didn't see it. She is a really strong mare and it is just lucky she isn't shod. My filly has been really beaten up. Thankfully nothing broken, but she is dragging her toe still from where she was kicked on her forearm. The gelding she kicked still has a big hard lump on his cannon bone from where she kicked him 2 months ago. She really means business.
 
No idea, but some horses just don't get on, just like people. Whether it makes sense or not! I have two I can't put together ever, even if they groom over the fence, because they would kill each other. I did try once, with someone else on hand and it was apparent within 10 seconds that I was right and we had to separate them. Each is fine out with any of my others.
 
My old retired mare took a dislike to one of my geldings a few years ago after previously being the perfect babysitter for my ridden horses.

I just couldn't trust her with him at all, she really did mean business and to prevent the inevitable large vets bill I had to buy another companion for him.

I'm not a fan of turning horses out alone as a long term solution, especially with yours being young - do you have the space that you can borrow a companion for a while?
 
My old retired mare took a dislike to one of my geldings a few years ago after previously being the perfect babysitter for my ridden horses.

I just couldn't trust her with him at all, she really did mean business and to prevent the inevitable large vets bill I had to buy another companion for him.

I'm not a fan of turning horses out alone as a long term solution, especially with yours being young - do you have the space that you can borrow a companion for a while?

I am eventually going to be on the lookout for a large loan horse for me and my husband to ride. My filly will be staying with the two year old because they are playmates and also their turnout arrangements will be different to the others in the winter.
 
Sorry to hear the filly and gelding were injured. If they are allowed to get used to each other with a fence in between perhaps she will grow to tolerate your filly? Could you put up an electric fence with wooden fence poles which is a bit more substantial but less effort than entirely new fencing?

I have a similar issue with my older mare who disliked my new mare . They were separated for a couple of months and now grudgingly tolerates the new one. I think she preferred geldings and maybe sees a younger mare as a rival.
 
Sometimes there is really no ryme or reason for this kind of behaviour, you are doing the right thing to keep her alone. We all know they will have their squabbles in the field but after witnessing a similar incident I believe some horses (like dogs etc.) are not to be trusted around others.
 
Sorry to hear the filly and gelding were injured. If they are allowed to get used to each other with a fence in between perhaps she will grow to tolerate your filly? Could you put up an electric fence with wooden fence poles which is a bit more substantial but less effort than entirely new fencing?

I have a similar issue with my older mare who disliked my new mare . They were separated for a couple of months and now grudgingly tolerates the new one. I think she preferred geldings and maybe sees a younger mare as a rival.

Yes, I do wonder if it is a jealousy thing. For a long time she and my mare were the only two mares amongst five geldings. My mare was very much the boss and so there was never a problem. Maybe now my mare has gone she feels she is the lead mare and doesn't want any new girls on the scene? I would need to cost out someone coming to do some more permanent fencing. I have two fields that are post and rail (one 5 acres, the other two), and like to use electric fencing to create smaller paddocks inside of these as necessary. I think I will have to build her a paddock so she is in the middle of the two groups of horses, but it will have to be double row between her and my filly.
 
Could you just leave one of the horses with her and the other one with your filly. I am sure if she is used to having company she will be very upset that she is now on her own even if she has got access over a fence. My elderly mare is very aggressive with other horses and it took over a year of grazing her with my gelding in the field next to my three miniatures before I could turn them all out together. They still avoid her and will move away as soon as she walks in their direction but she no longer chases and attacks them which she was doing over the fence for the first year I had them. Give the mare time to adjust to your new filly and it may take a long time.
 
Thanks for the replies. There is no way I will ever let her in with any other horse other than her son now. But at the minute her son goes out 24/7 with my filly and my gelding. They are real playmates and a lovely happy group of three which works really well as a herd. I wanted to add her to that herd and had put her next to them for two weeks and all had seemed fine. My instinct told me not to put her in with my filly, but I told myself I was being too precious after losing my mare and it would all be fine. It wasn't. I will never go against my gut instinct again. I will build her a paddock with two rows of tape between the two herds so she will have company, but I just cannot risk her out with any of them unrestricted. She really means business.
 
Thanks for the replies. There is no way I will ever let her in with any other horse other than her son now. But at the minute her son goes out 24/7 with my filly and my gelding. They are real playmates and a lovely happy group of three which works really well as a herd. I wanted to add her to that herd and had put her next to them for two weeks and all had seemed fine. My instinct told me not to put her in with my filly, but I told myself I was being too precious after losing my mare and it would all be fine. It wasn't. I will never go against my gut instinct again. I will build her a paddock with two rows of tape between the two herds so she will have company, but I just cannot risk her out with any of them unrestricted. She really means business.

Could it be related to being in season? My normally placid mare chased her best friend tonight but she is just into her first season of the year and touchy!
 
I would imagine she now sees herself as 'lead mare' having lost her friend who she was submissive to, and she's using her new power over your young filly who she probably thinks is a rival. Being young, your filly is not goimg to assert herself so this behaviour will probably continue. Maybe time will tell if out with a fence in between them, but I think you are right OP to split your paddocks.
 
It could be that she's actually ill. My mare is fine until something is wrong with her, she wouldn't dare go for horses above her in the herd but anyone beneath her she will become quite nasty for seemingly no reason.
 
my mare was really aggressive to my gelding when I first bought him! she was fine the first day but then she realised he was mine and she was nasty but only shoeing him off and biting him for no reason, she'd threaten with her back legs but she'd never purposely kick! I was really worried and even asked the vet he said that she would get over it and there would have been a reason for her doing it! and soon enough, a month or so later she was there grooming him!

so maybe its just this mare is trying to say that shes the boss! okay shes doing it in a very aggressive way, which isn't acceptable but hopefully she will accept her soon and things will be okay! I would keep at least electric in the way just in case!!
 
You sure that you didn't end up with my horse? Well, she has been that way for most of her life. It's fun. The saving grace is that she respects electric fences and doesn't act like such a t w a t towards other horses when under saddle.
 
Maybe its because the boss mare went. I had similar on a livery yard. There was a boss gelding, next was a mare, then next a gelding R who was friends with this mare. Mixed group of mares and geldings aprox ten horses all was fine for a year. Then boss horse went to another yard and things went wrong. R decided that my horse and his friend (the only other geldings) could no longer be part of the herd. A big field and if they even looked at the herd from the other side of the field R chased and kicked them. We had to put them in another field in the end.
 
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