If it is not particularly serious, don't worry, the dog will heal itself, and the dog's recovery ability is very strong. But do as little activity as possible, and it will be fine in a few days. You can gently move your fingers and spray some drugs that will damage it.
If it's serious, you have to go to a pet hospital for treatment.
Precautions for the first dog:
Keep the puppy warm, deworm, vaccinate, eat and drink well, and there will be no problem.