After trying unsuccessfully to get a foal off my mare for 3 years I decided to start riding her again to get her in shape with plans to switch from her previous career of reining and ranch riding to Barrels. She’s 15, 100% sound (never had injections). But man she has been more hot, excited, impatient tied up and wound up. She’s extremely well broke but I feel like I’m on a fractious 2 year old. I was thinking ulcers but now after a lot of research and reading I’m actually thinking it’s maybe a magnesium deficiency. Anyone dealt with this? Signs and symptoms you saw? Best magnesium supplement you found? Thanks. 

Magrestore by Performance Equine has helped my horse a ton. If he's off of it, I can tell within two days and it takes him a week to get somewhat back to normal. He's a spooky horse anyway but he's downright overreactive and awful when he's off his mag. 

I've been using Mag select from Oxygen for the past 120 days, and have noticed a huge difference in my gelding. It's a pelleted supplement, and he eats it right up. My trainer took her rodeo horse off of it this winter, and it starting to leg her back up again and she's been very spooky lately, and this is a horse that has rodeod all over the US. She's going to be put back on the Mag Select soon! 

I've fed magnesium to mine and could tell a huge difference in her. She was spooky, reactive, setting back, acting stupid, tight throughout her whole body, a butt under saddle, you name it. I started researching because I was to the point of giving her a long lasting sedative to see if that would help any. Magnesium started coming up in my research. I bought a bag of Mag 5000 from MVP and started feeding it. Within DAYS I could tell a difference. I ran out and after about a week my husband asked if she was off her mag. I said yes and he told me to order her another bag ASAP. It made that big of a change in her. I only fed 2 bags I think to her but it must have been enough to help. Today she is a completely different horse and I can honestly say that mare loves me. She will leave her food to stand by me. Just an awesome horse but those first 6 months were rough. Now if I have a horse that I suspect could be deficient, I immediately start them on Mag 5000. 

Look into Quiessence, great supplement

I have a similar mare that I've owned for 7 years. She has always been this way so it's nothing new. She is broke and very sane, just overly anxious. After contemplating it a year, I finally started her on Magnesium a week ago. I'm not sure how long it takes to see results. I ran her over the weekend and she was still fairly hot but she did seem focused during her run. So that may something. It's cheap and worth a shot. 

I started adding in magnesium to my horses feed a few days ago after theyve just kinda been sitting idle porking out on all the grass that's come up.. and after my good horse freaking out about loading into the trailer which hes never done and spooking way more than usual.. I'm really hoping that'll help.. I had a bag of Animal Element Magnesium citrate on hand so that's what I'm trying right now.