I just had a scare with my little girl. She started limping on her right front. And at age 9, that's prime age for OS. I just had a hemangiosarcoma scare 2 weeks earlier. She had the dermal kind and I ultrasounded her abdomen to make sure it was dermal and not a met.
So at the vets he knew I was worried about OS. He said he's almost sure it's the tendon. Tendonitis. But what I didn't know is that it's very hard to clear up and if you can't clear it up, you can get crystals in the tendon and end up with a permanent limp.
She was on Rimadyl for 3 weeks and no running or playing. Just leash walk.
She did heal thank goodness.
So check the tendonitis route. I don't know if metacam works on tendonitis. My vet said tramadol, while a pain killer helps with pain, it's not a good antinflamatory. That's why he put her on Rimadyl.