Why can't I get joint supplements on prescription for my dog?

It's a legitimate frustration. The reason joint supplements aren't prescribable in most markets is regulatory classification — they're licensed as pet food supplements rather than veterinary medicines, which puts them outside the prescribable drug category. It's not that they don't work; it's that they haven't been through the pharmaceutical licensing process that would make them prescribable and potentially insurable. Is the cost of a specific supplement making management difficult, or is it the principle of it?

£65 a month is real money over a year. A few options: first, check whether your pet insurance policy has any supplement coverage — some premium policies do cover licensed veterinary supplements. Second, YuMOVE subscriptions typically offer 15–20% off versus single purchases — if you're not already subscribed, that's a meaningful reduction. Third, if the ADVANCE 360 is working, the honest question is whether he could be maintained on YuMOVE Senior at lower cost with a monthly spot-check — some dogs at 9–10 on ADVANCE 360 stabilise enough that Senior maintains the improvement. That's a conversation worth having alongside his next vet check.