My five year old mare frequently holds a mouthful of water for extended periods of time. I come into the barn and she'll dump out this big mouthful of water that she's been holding. This morning she was standing in the corner of the barn and I went over to check her out. I felt her face and it felt swollen on both sides, but when I pushed on her cheeks a little it turned out it was just water that she then let come pouring out. She has done this on occasion for at least the last year, but it seems more frequent right now. She had her teeth checked and floated in April and the vet didn't notice anything unusual. I forgot to mention the water thing to the vet at the time because it hadn't happened in awhile. Does anyone have any idea what this is about? She seems otherwise ok, eating, grazing, etc. She does seem a bit lethargic, but it has been quite hot and she's a little overweight (which I'm working on). Any thoughts would be welcome.