It may depend on where you are. My vet clinic uses a compounding pharmacy that does (at least) 50 and 100mg tablets. I was given some 10mg capsules from another clinic.
What's the strength of the Tramadol?
Here's what Cora (~65lbs/~30kg) was given at the end: Metacam 35kg dosage (bit extra for her weight) and Tramadol 100mg every 6 hours. She still limped, but she was less unhappy.