There are several options, none of them particularly good in this location. The first would be acute allergic reaction, often called anaphylatic shock. Other options include infection, foreign body and cancer.
Regardless of the cause, this would be a good reason to take your dog to a veterinarian for examination and treatment.
No.
no why would it swell. get it checked out.
what causes the left shoulder to swell
You probably have a serious infection and need to see a doctor immediately.It's possible that your Eustachian tube is stopped up
No.! Wth.!? I have my tongue pierced and I have no issues with it..
It is having an allergic reaction--you can give a dog Benadryl--and take it to the vet before it can't breathe! Like now!
Solution causes a cell to swell by osmosis
Infections causes it to swell
There are many things that can cause a swollen tongue such as an allergic reaction. Body parts swell up and sometimes interfere with your ability to breathe when you have an allergic reaction.
I don't think that such a phenomenon actually happens. It is possible that some things could cause both symptoms, but the tongue swelling is almost certainly not a product of the confusion.
since the metal in the piercing is filled with iron the iron will irritate the tongue therefore causing the tongue to swell and turn yellow
I would be sure to check your dogs for worms and have a general blood test run. This would be the best starting place.