What is this called and why does it hang out of my dog's mouth?

The pink bit in the photo below has been hanging out of my dog's mouth for the last 3 months now. I have no idea what it's called or why it's happening, only that the one on the other side is fine and remains inside. As a result of being exposed it very noticeably dries out while the other one stays wet and moist from saliva. Should I be concerned? Is there a fix? 15 yr old Cattle Dog x Staffy Female Thanks

Hello perhaps this is rugal fold on the dogs' inner lips.  These usually stay on the inside, so I wonder why they have popped out.  Answers can include changes to the nerves that supply the muscle tone to the side of the face, or changes to the muscle itself or even to the tongue.  Your vet could do a neurological exam to try to test the innervation and salivation to the area.  I thought about lumps (benign, cysts or otherwise) on the inside, pushing the lip out or affecting the nerve.  Primary nerve damage, due to trauma or infection.  Brain changes.  Changes to the musculature of the mouth, again in connection with something more serious.  Sometimes, something far simpler such as a tooth injury, bee sting or skin disease could have a rile.   I agree that it you are right to be concerned; whether or not there is a fix, depends upon the cause in this particular case.  It seems to be a good idea to talk to your vet about the likely differentials in this particular case and any recommended diagnostics, particularly if they will make a difference to the case outcome.  Your vet may also be able to help you to treat the symptoms a little.  Please will you let us know how you got on?

Hello    This may be a rugal fold from the patients' inner lips.  These usually stay on the inside, so I wonder why it would have popped out in this case.  Answers can include changes to the nerves that tone the muscle to the side of the face, or changes to the muscle itself or even changes to the tongue.  Your vet could do a neurological exam to test the innervation and salivation to the area.  Nerves can be damaged by trauma or infection at the level of the nerve or the brain.  Other possibilities include localised lumps (benign, cysts or tumours) pushing the lip out or affecting the nerve. Sometimes, something far simpler such as a tooth injury, bee sting or skin disease could be responsible.   I agree that it you are right to be concerned.  Whether or not there is a fix, depends upon the cause in this patients' case.  It seems to be a good idea to talk to your vet about the likely differentials (possible causes) and therefore the recommended diagnostics.  Your vet may also be able to help you to treat the symptoms a little.  Please will you let us know how you got on?