My mare had a series of 3 Cartrophen injections in the second half of last year. I can't recall the dose each time, but they seem to have made an enormous difference.
My old pony had them and they made a huge difference. I think he had 4 injections. The dose was just 1 vial per injection but I don’t know how much was in each vial.
Initial course of 4 injections (1 vial per jab) followed by a single top up at about 6 months.
My vets are conflicted as to whether to allow their clients to get a prescription for the cartrophen (it’s usually a lot cheaper from VioVet et al). Mine did issue the prescription in the end, so I self jab my horse, which saves on vet visits fees.
ETA I remembered that wrong, the vets agreed to supply me with the cartrophen themselves but they price matched VioVet for it, which meant that they sold it to me at a loss.
My horse had the intial course of 4 jabs (10ml vial each time) and now has one vial approx every 3 months. Works realy well for him. my vet supplies them, and the syringes/needles - and I inject him
Worked wonders for my big old grey horse. Has a list of niggles as long as your arm and took 10 years off him. He has a wondeful sharer who potters about with him, but he hasnt done any serious work in 10 years either and it keeps him comfy without the need to bute. He get 9ml of the dose and the dog with very artheritic elbows gets the other 1ml. My sister honestly thought the dog would have to be PTS he was so bad at one point...2 years later he is still happy. We get a prescription and online buy. Top up when required after the initial 4 loading doses.