The reason the tooth is brown is because the root inside is dead, It won't hurt other then esthitic reasons to wait to get it fixed, root canal is better then extraction but is more costly, but what I am saying is you can save the money if you need to... the tooth will wait. Your baby should not be in pain, once the tooth is dead there is no feelings left, and if it is brown it is dead. Usually a dead tooth comes from blunt trauma(meaning he hit his tooth on something) which may not be very much trauma for their lil teeth. I have only dealt with human teeth, but I hope this helps, by the way to have a tooth pulled can cause other teeth to eventually shift.... I don't know if this would be a problem other then esthetically (for looks).... but when you remove a tooth and don't have a spacer put in, the other teeth will shift around, turn, and move... (I don't think their is such a thing as a puppy spacer...but who knows) I am new to having a yorkie myself, just not new to teeth.
Dot