The good news about most minor wounds inside of a dog's mouth is it will normally heal itself with no special attention. Deeper, more severe cuts, however, need to be treated by a veterinarian.
There are times when a pet's behavior indicates they have a laceration or injury inside of his mouth, such as difficulty eating or pawing at the mouth.
If your dog is displaying behavior like this, and you have not seen any blood or other indication of a cut, then he may have a foreign object wedged between his teeth and gums. Think popcorn kernels.
If he will allow it, check your dog's mouth to attempt to locate the source of the problem. If you are unable to find the problem and the behavior continues, speak to your veterinarian as there are a number of issues your dog may be having. If you do locate something in your dog's teeth carefully and gently attempt to remove it. Try first with your fingers. If that attempt fails, try tweezers or a blunt object like the handle on silverware.
If you are unable to remove the object, contact your veterinarian, as it could lead to a serious infection.
More Severe Lacerations
When your dog's wound either appears to be large or deep, or the dog will not let you view it, chances are it will need the attention of a veterinarian. Don't be surprised when your veterinarian puts your dog under general anesthesia for the exam. This is a normal precaution taken to ensure the safety of both the veterinarian and your pet.
Some severe lacerations and wounds may require a minor surgical procedure, which most vets will do while the dog is already under anesthesia.
You will likely also be given a prescription antibiotic to help ward off infection.
The Dangers of Unprescribed Antibiotics
Due to the availability of canine antibiotics on the Internet without a prescription, it may be tempting to take shortcuts for the sake of saving money. This would be an ill-advised move. Not only may it not be the best way to help your dog's wound heal, there may be side effects.
Using antibiotics when not necessary or improperly could result in illness in your dog, including diarrhea, bone marrow suppression, and permanent deafness.
Also, like humans, administering an antibiotic can make your pet's immune system build a tolerance for that particular antibiotic, making it ineffective in the future.