I' m not familiar with the surgery whrere they shave the bone off so it fits in the socket bettet, I would guess they are talking about a femoral head and neck resection and yes she would be done as a hunter if this was done and also that surgery does not work well on dogs that get over 50 lbs. Essentially they cut off the ball of the ball and socket joint, over several weeks scar tissue fills in where the joint was and the dog has a functional leg, works really well on little dogs and not very well on big dogs. Ask what the surgery was again and let me know.
Cosequin is a combination of glucosamine and Chondroitan sulphate. It is known as a neutracutical, an all natural product. This is also the reason I only use Cosequin, there is no regulation on the manufactue of these products, you could put table salt in jars and sell it as glucosamine and no one would ever check you out. The company that makes Cosequin spends a lot of money on INDEPENDANT studies to show you that the product they are selling is actually what you are getting. They are not required by law to do this and they are the only company that makes these products that spends the extra money.
Back to your original question. Joints are where two bones meet and motion takes place. On the ends of the bones there is articular cartilage, a special kind of cartilage that is very springy and functions as a shock absorber. There is also fluid in the joint that is very thick that serves as a lubricant and also as a nutritional source to the cartilage. Glucosamine and Chondroitan sulphate are both integral parts of both the cartilage in the joints and the synovial fluid in the joints. In a diseased joint outside sources of these molecules have been shown to increase the viscosity of the fluid, decrease inflammation, help return the joint to a more normal state and protect the cartilage. Articular cartilage does not heal nor does it regrow once damaged, this is why we have/get arthritis. These products help to protect the cartilage in a diseased joint. They have been shown to have no beneficial effect in normal joints, only inflammed ones so they don' t work as a preventative. If your dog has dysplasia there is inflammation in the hip joints. Hope that didn' t confuse you, let me know if I did or if you have any more questions.