So my mare has been a major pain in the rear lately with the horses she goes out with. She's ALWAYS been a dominant, alpha mare but never nasty for no reason. She has lived out with other horses her entire life (She's going on 9yrs old - I've had her since a weanling). Probably over the last couple months, she has now had a number of altercations with the other mares in her herd(s). She moved to 2 different pastures (all mares) and had some scary incidents in both where she just wallops the horses.
So now she is currently in solitary isolation in her own paddock for the time being. BO asked me to pull hind shoes because she needs to go back with other horses for winter. I WORRY about this! I don't think taking her shoes off is gonna help too much if she is being that aggressive. I would DIE if she caused another horse to break their leg or something else tragic. If she's going to continue to be like this, I almost prefer private turnout or just with 1 other compatible horse but I don't know if that will be possible long term at this barn. I worry about the other horses in this situation.
What could cause her to all of a sudden become unnecessarily aggressive? Is there any remedies for this that I could try? Could ulcers cause her to become more aggressive to other horses? I've been thinking she could be getting a little ulcery. She's been grinding her teeth about 20min into our rides over the last month or so along with what I thought was her 'itching' her sides but realize now it may be her biting at her uncomfortable belly. Her diet is pretty light. She is a BIG Easy keeper TB (never raced)...she gets a ration balancer, some alfalfa pellets, magnesium (magRestore), Vit E, and a joint supplement. She's worked about 3 days a week for approx 45min-1hr each day.
I might try treating for ulcers. IMO, if they are dealing with any type of chronic pain there is no reason to think that wouldn't affect their behavior. That would probably be where I started along with a physical exam from the vet. Especially given the teeth grinding and "colicky" behavior.
I might also see about doing an ultrasound on her ovaries, especially if the ulcer treatment didn't help. My mare, although always the boss, is usually quite civil to the other horses if they respect her space. But the few times I've seen her purposely pick fights (and be absolutely NASTY) in turnout seemed to coincide with her first heat cycle of the year, and I think there is either a hormonal or pain component to that. Obviously, your mare is not going through a first cycle of the year, but if she is having pain in that area or hormonal changes, especially if this is unusual behavior for her, it might be something to rule out.
Ulcers or ovaries or both. If she is having ovarian problems, that stress could lead to ulcers as well. You've already got the magnesium covered, I'd certainly keep her on it as stress depletes magnesium.
I'd go buy some Ulcergard and give her 4-5 tubes (one a day) just to see. If you see marked improvement, you have your answer. I'd have her ultrasounded as well for ovarian issues. Maybe she has a retained follicle. Those hurt like hell. Ovarian cysts are no walk in the park either.
If you do "try" turning her back out with other horses, please at the very least pull her back shoes until you see how she does.
It can definitely make a difference in the extent of any potential injuries.
I have to agree with above posters and I would pull her hind shoes too, has she ever been without them?
With my mare I have to keep her off of grass to help regulate her hormones. I'd check on the amount of clover in the field after you rule out ulcers and ovarian issues. I keep mine on smarmare harmony which has raspberry leaves in in and i think it made a big difference in taking the edge off of her aggressive behavior. She's also on mare plus which is like a mare specific multi vitamin.