I'm not real sure what is going on, but I'm probably lucky nothing serious has happened.
I am currently riding a Thoroughbred mare named Sassy, I live in upper Minnesota so it gets a little chilly in the winter. Her owner had bought a blanket for her at an auction and ended up being her size. In the fall she had lost a ton of weight because he had her over at another person's place and they were to lazy to walk outside and grain her plus she was not comfortable over there, always sad and never got worked with. So she lost a TON of weight. I got her back coming into winter and we had a tough winter so I put the blanket on her to help her. She doesn't grow a massive bear coat. But her blanket would ALWAYS slide to the side, this one had leg straps, and a girth strap. I tried adjusting the straps different ways and it still slid.
For showing, I bought her a cotton sheet. I used it for the first time last night. I put her in in the stall over night and came this morning and the blanket had slid sideways a ton again! This one only had belly straps.
I remember putting another sheet/blanket on her some other time and it slid also.
Any ideas why this is happeneing with every blanket?