This is a classic tiger salamander case. They are so often picked up by people who havn't a clue as to care, and when they get bored of them, ship them off to good folks like you.
The treatment will depend largely on the extent of the wounds. First and foremost will be proper husbandry. Super clean, while these guys should normally be kept on a dirt style substrate, for now, use many layers of damp paper towel. Flush the wounds 3-4 times every day for a good 3-5 minutes. This might be enough. To play it safe, I would schedule a vet visit to have the extent of the wounds examined. Amphibian medicine is a bit more tricky than with reptiles, but a good herp vet should have the resources to sort it out.
Check out the amphibian forums here on kingsnake, or perhaps also check www.caudata.org for information on tiger salamander husbandry.
Ian