I have a 26 yr old mare and she is a no fuss kind of girl, until recently and just with one issue. No other issues that I'm aware of, always been in good health, pretty easy keeper. The past couple of weeks she will pin her ears and get SO MAD when I put her blanket on. This is not like her and at first I thought she was just being sassy because we recently moved pastures & pasture mates around. Now, after a couple of weeks of this it dawned on me over the weekened that she is trying to tell me something, but I've never experienced this before so I'm not sure what. Could it be ulcers or related to her cycle? Would it begin to happen that fast? Huge difference from a month ago to now, and shes lost a little weight too which I thought maybe it was just the time of year and shes older, plus it has been really cold and wet lately. I have a vet appointment for next week but just thought I'd come here and educate myself before so maybe I have a better idea of where to start with questions and concerns for the vet. Currently her diet is full turnout, plenty of hay and equine senior 2x a day. TIA! 

I would get a couple tubes of ulcerguard and give heer half tube a day for few days and see if you see a change. If its ulcers that will usually make them feel better so you can rule it out. If she does return to normal then you have to go ahead and treat for ulcers. 

Apparently you must be putting a blanket on her for your feelings. 

She is trying to tell you she doesn't want it on.

Something is wrong. Have you checked between her legs to see if maybe straps are rubbing?

Could be static ? I know sometimes when I go to take blankets off there is some static I get zapped right along with them. Not a pleasant experience. 

Have you changed blankets recently? Maybe the one she is wearing is making her wither and/or chest sore from not fitting properly.

60cc of Maalox will also do the same thing for an ulcer check, lots cheaper. I give 80cc since it's like milk and some will run out 

I have looked her all over and there are no rub marks anywhere, we havent changed the blanket and no static. So odd. I have quit blanketing her for now and we see the vet Monday.