Dog holding tail down

Question
Yesterday afternoon my four year old chocolate lab started holding her tail down against her. She spent the night laying around and moaning. It seems painful for her to sit down as she won't hold that position. She had a bowel movement yesterday, but has not eaten today. She will accept treats.
Thank you for your help.
Jill

Answer
Tail head injuries are not uncommon with dogs. It could even be her sacrum,which is at the back of her pelvis. She might have jumped off of something that strained it, or ran to hard and turned, etc. She could have even been bumped by a car. Check her inner thighs to see if they are scraped at all and her toenails to see of they looked shredded on the ends.
We see dogs that get their butts bumped trying to cross the road and all you see later is some road rash and a dog with it's tail tucked. Now some dogs actually fracture the last vertabrae and cannot even lift their tails, but those usually hang down really limp.
If she isn't better tomorrow you should have the vet look at her.
You can give a small buffered aspirin if she isn't on any blood thinning medication at all. She is probably at least 50 lbs so one aspirin will help. Do not give her any Tylenol or Ibuprofen. Just buffered Aspirin like Bayer but read the label!!
Call the vet in the morning if she is still tucking it.
Let me know what they find out.