Rats being rats are bound to have a little tussle now and then, and sometimes it can get a little more serious resulting in an open wound.
What do I do?
Gently but firmly restrain your rat and assess the damage. Use tweezers to remove any bedding (or similar) that might be stuck to the wound, and control the bleeding if necessary (see Bleeding). Use a syringe, without the needle, to wash out the wound with a saline solution. Apply an antiseptic cream (like Savlon) to the wound to clean it further. Repeat this procedure twice a day for the next few days until you see that its healing with no infection.
If you see signs of infection, seek advice from your vet immediately. If the wound is large, and stitches might be required, then see your vet as soon as possible! Never punish your rats for fighting. Although it might have been serious, they wont understand why you’re punishing them.