Dog won't stop bleeding?

Call the emergency Vet. Many times they will help you with simple things right over the phone.

Add: Don't bother with getting the Styptic Powder. I have some here and it's for external use only.

usually if a mouth cut is not to bad it will stop on it's own. Part of the reason he may not be able to stop it is he may be anemic, which means he does not have enough white blood cells, so the platelets won't be able to clot up, because the blood is to thin. If you found him buy the road and have not seen a vet already, do so as soon as possible, tell them about this, and they can suggest different reasons why. They will also most likely want to run blood tests, this is in your dogs best interest! Best of luck!

Styptic powder should not be ingested, but you can use some baking flour as a substitute. Dry it, apply some flour, apply pressure for a couple minutes and keep him calm for an hour or so to let it clot enough to not break open again.

If you can't get to the vet then maybe you could see if the vet could come to you. Try applying pressure to the wound but if he has broken a tooth or something then you don't really have another option but to go to the vet.

if you can get to a pet store they should have something called something like stipic. its almost like a pencil. it is an oldfashioned remedy but they still sell it. if its a really bad gash where you can see the bone then he needs to be taken to the vet for stitches

Let it clot. Don't clean it up. lips are big bleeders even when the cut is small.