Dosage for tramadol for dogs six pounds?

None.

I've been told dogs can take codeine, and Vicodin contains the synthetic version of that, however, Vicodin also contains Tylenol and that is a no-no for dogs:

Can_you_give_a_dog_Tylenol

In an urgent situation, I would give my dog a half or whole aspirin (depending on their size) until I could go to the store or pet store asap to get the kind specifically made for dogs. Dogs should take the kind of aspirin that is buffered or coated, so as not to injure their digestive systems. Also, don't forget that aspirin "thins the blood" & is liable to make your dog bleed more if you're dealing with an injury or wound situation.

If you have an older dog that is suffering joint or Arthritis symptoms, Rimadyl is commonly prescribed by vets for pain & inflammation & you can find it available on internet sites that offer pet medications quite frequently. Also, I got one old dachshund to 17 years & another to 14 years of age, pretty pain free using Glucosamine/Chondroitin in a daily chewable, canine tablet.