A bag will last you approx 3 months... I would start with a bag of the regular formula if your concerned and when your finished, switch over to the Plus. I'm using the Plus, cause my Lad needs it.... I was using two different formulas but I switched over to using the same formula with them all... but I am just cutting the dose way down with the puppy... so I'm not over doing it with her, that was my vets reccomendation with her. Shes a chinese crested and they are like "Tigger" from Whinne the Pooh... Bounce a Bounce a Bounce... Her joints take a beating! lol So he said it could'nt hurt to have her on it!
So I guess you could go both ways... do the plus... like I am and cut the dose down... or start with the regular formula....
Oh... and my pup is 4 1/2, well, maybe 5 months now... I'd half to check papers...
not positive.. lol time flies!