Once Stan is off all meds and it has been determined it's arthritis try him on Cosequin with MSM. A member here took her duck to the vet when her duck was having trouble walking the vet recommended Cosequin with MSM. She also sent me some to try with my Muscovy drake who had injured his leg and walked with a limp which I believe caused arthritis, he passed away 3 weeks ago at the age of 12.5 years but his last year he had no limp which I believe was because of the Cosequin.
That may be something to ask the vet about if it is arthritis.
That may be something to ask the vet about if it is arthritis.