> To stablise the glucosamine sulphate the tablets had high doses of salt added
D-Glucosmine is a natural product, however it needs stabalising, it is stabalised either with potasium or sodium (salt!) to make D-glucosamine sulphate or with hyrocholic acid, which makes D-Glucosmanie hydrochloride/HCL. Apparently some manufacturers of glucosame sulphate
(even gluc. sulphate that is made with potasium)
are
'filling' with table salt 
Glucosamnie HCL is made from shelfish or veg sources.
Glucosamnie sulphate is made either from shelfish sources or is artificial.
Glucosamine HCL is also more effecxtive than Glucosamie sulphate, I think it's something like 85% of the Gluc.HCL is 'effective' compared to about 65% of Gluc. Sulphate, which means to get the same effect of 1500mg og Glucosame HCL you need a LOT bigger dose of Glucoasmie Sulphate
(my vet told me this was the reason they supply only Glucosamine HCL and NOT sulphate).
It would be good to see that vet report in full as it could make many people, who are giving a good quality, safe version of Glucosamine Sulphate, panick. But, that said, it think it wise to stick to supliments that are labeled as safe for pets. I have come accross a few glucosamine supplimets that seem fine for pets on the face of it (allthough they are intended for humans), but when investigating the ingredients have found there to be worrying contra-indications for dogs, especially ones on NSAIDs - just the sort of dogs that may be given the suppliments in the first place.
I toook the ingredients list to my vet first to get the all-clear, it only takes a moment and he was happy to help, worth the trip for peace of mind.