I have Willow on 500mg of green lipped mussel extract twice daily. Its natural and easy to give her a capsule with her meat. We sell loads of the stuff at work for humans and animals. Took the guess work out of calculating the dose of glucosamine and chondroitin supplements which often come at a variety of different potencies and sometimes have other ingredients added.
I'd be very hesitant giving aspirin to a dog unless advised to by a vet, when it isn't even safe to given to children and causes many gastrointestinal problems in humans. A dog can't tell you it's tummy is sore from ulcers and stomach bleeds can be very slow, cause anaemia and possible death if not diagnosed in time.
Tramadol commonly causes vomiting, headache, dizziness and should definitely only be given if prescribed by vet (not given some you found in the medicine cabinet!).
Even herbal medicines should be discussed with your vet before giving to a dog. Natural doesn't = safe