Hello, I Have A 100lb Boxer He Has Severe Arthritis

Hello, i have a 100lb boxer he has severe arthritis pain,they give him carprofen 100mg 2 times daily, he needs a pain killer ,maybe both What is one of the names for a non natural pill, like vicoden, percocet etc, nobody will tell me not even the vet, we don t give pain killers to dogs my vet sad, he is in perfect health, except for ,R.A. Thankyou