How long after taking aspirin can my dog take metacam?

My dog was experiencing pain early this morning so I gave him half a baby aspirin (about 17 hours ago) to relieve him until I could get him to the vet. When I was finally able to get him checked up a few hours later I was given metacam for him. He hasn't taken the metacam yet since I was scared it would react somehow with the aspirin. Anyone have an idea? I forgot to ask the vet about all this and there's no one I can phone at this time. Thanks!

It's fine. The dose of aspirin you gave him was tiny (appropriate for a four pound dog), and would have cleared his system long before now. It is steroids like prednisone which have to be stopped for some days before using NSAIDs like aspirin or Metacam... combining NSAIDs is done frequently.