Could you elaborate on your dog's cartilage problem Belinda? It might help us to give you more information. The problem Angela describes is called "slipping patella" & is quite common in toy breeds but is also sometimes seen in Cockers - it can be hereditary or caused by trauma. If your dog has this condition, sometimes surgery is needed & sometimes not - it depends on the severity of the problem. There are also supplements which can help, like Glucosamine.