knot around anal opening

Question
My 13 yr. old Shihtzu has been holding her tail down all day and usually doesn't, so we check her over and found a pretty big tight knot around her anal opening.  We have a vet and tried to call him at home, but no answer.  We called the emergency pet clinic and they wouldn't try to answer questions, but would charge $75 just to see someone.  I am just wondering what this might be, I think maybe an anal glad, but wondered what else it could be and if there is anything we can do until monday when it won't cost so much $, or if it should be seen right away?  Do you have any advice?  

Answer
Hey Dana. This sounds like her anal gland could be getting really full. If it's not expressed soon, it could possibly rupture. I know this sounds disgusting, but you could try to express it some if you want it to wait until Monday. I would hate for you to have to pay an emergency fee just for an anal gland. To express it all you have to do is get a rag & put your thumb & index finger on each side of her anal area. Then with a little pressure, gently squeeze in & push up. This should help give her some relief until you can have the vet fully express them Monday. Let me know if you have any other questions. Thanks!
-Heather