Never heard of pedigree joint care, reading other comments i assume they are some kind of chew, and would guess any 'joint care' contained in them is minimal. You really need to be looking at her weight, and as labs are prone to weight gain, i wouldnt give her anything in addition to her food in the form of treats.
There are numerous products on the market, green lipped mussel works for Kita, so you could try that, or glucosamine, also available from Holland and Barratt, or some of the other joint products available on line, like Synflex, which is easily added to the dogs food as it is a liquid -
http://www.collienet.com/collienet_shoppingmal l_hygiene_Petcareproducta.htm
I used a Bioflow collar on one of my dogs once as she unfortunately developed a limp from arthritis at 6 years of age, and she lived to nearly 14 before her back legs finally gave way -
http://www.collienet.com/collienet_shopping%20 mall_veterinary.htm