[yorkietalkjilly]

If she's not ill, she probably is feeling insecure/stressed somehow or under challenged, which stresses some dogs. I've heard OCD can come from either of those and who knows what else. Block her ability to stare out the glass, lure her away with a training program of 5-10 minutes, a game of ball or tugowar, a high-value treat and each time she breaks away, lots of love, praise and treat. If you don't break the OCD pretty early, it's far harder to do and she may start to sit there and drool, go in circles, whine. Watch her ears when she is looking out the glass and have a training session which is that every time they go up and she focuses, instantly distract her away, into another room and give her a very high-value treat or take her out front for a quick walk. Repeat - let her go back to the glass, watch the ears and respond the same all over. Repeat it about 5 times each training session. It will break her intense concentration and soon when she sees the squirrel stimulus, she will expect not to be able to focus on it due to the expected distraction coming and look to you for it expectantly. Anything and several different things to keep her distracted for a while until she loses the OCD tendency and can just treat squirrel watching like another fun activity. That has worked with any dog I have had with an OCD tendency.