Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner. If you would still like assistance, can you tell me:
Do you mean she is currently on Deramaxx and had Rimadyl
How often does she do this?
Any irritation, redness, sores, wounds, or lumps near or around her rectum?
Does she leave any material on the carpet after doing this?
Does she seem sore otherwise?
Can you post your photo on a website like YouTube and then paste the web link here for me to check?