The weight of the dog has some bearing on the outcome on this surgery. In the surgery, the ball portion of the hip joint (the femoral head) is removed and the bone smoothed, if necessary, so that no bone to bone contact occurs between the pelvis, which contains the now empty socket and the remaining portion of the femur. The joint is not stabilized, it is destroyed. While that sounds bad, in almost all dogs under 40 to 50 lbs in weight, this surgery will provide reasonable comfort. A “false joint” forms, consisting of fibrous scar tissue around the bone end. This forms in the muscles over the hip, which fortunately are strong enough to provide some stability. It is less painful than leaving the dislocated femoral head rubbing against the pelvic bone.
The shoulder joint is naturally constructed in a similar fashion, although it has more stabilization. In dogs over 50 pounds of body weight there is more concern that the joint will not be functional due to the need for more weight bearing capacity. Most of the time, there is still reasonable comfort even in big dogs but the outcome is more questionable in these dogs.
There are alternatives.
1) Stabilization of the joint can be attempted. Many vets are reluctant to do these surgeries because some of them are technically difficult and all of them have a moderate failure rate. It is disconcerting to do surgery, collect a large fee, have to explain the failure to the client and then have to go back and do a femoral head ostectomy anyway. There are several possible stabilization procedures, including pinning the femoral head to the hip socket, moving the portion of the bone where muscle attachment occurs to a different site on the femur to provide more stability, toggle pinning the femoral head and several other stabilization techniques. It may be necessary to ask for referral to a surgical specialist for these procedures as many general practitioners are not comfortable doing them.
2) Total hip replacement. This is an option in some cases when hips can not be stabilized but it is necessary to consider this on a case by case basis. Again, this surgery requires referral to a surgical specialist in most cases. Very few veterinary practices have the capability of doing hip replacement surgery.
If an alternative stabilization technique doesn’t work, femoral head ostectomy remains an option. You do end up paying for two surgeries when one of the other stabilization methods fail but if they work, the outcome is better for your dog. The success rates of the various surgeries would depend a lot on the individual surgeon’s experience and skill.