Bernadine Poling on Canine Joint Disease 101

I enjoyed your movie on arthritis.I have a Border Collie who will be 14 yrs. old on Jan.1,2011. I give her 500 mg of glucosomine and chondrointon.Is that enough dosage.She weighs 70 lbs.I don't want to give too much as I don't know if it could hurt her.Thank you.